In-situ formed single solution hydrogels with covalent bonds, composition design and medical procedures using hydrogels

Abstract

Compositions, methods, and uses for forming a one-component system of in-situ hydrogels are described. The one-component system is effective for forming a stable single solution containing a precursor that provides electrophilic and nucleophilic groups that chemically cross-link upon contact with physiological fluids associated with important physiological tissues. The one-component system can be administered using a variety of delivery carriers, including injections, needles and needleless catheters, and sprays. The single component system may be used to achieve multiple injections from a single syringe through a small bore needle or other dispenser. Methods for perfusing an in situ formed hydrogel into one or more fallopian tubes transcervially are described.

Description

[0001] Fields of use

[0002] Aspects of the invention relate to compositions and methods of using a one-component system to form in situ hydrogels. The invention also relates to stable hydrogel solutions that chemically crosslink when in contact with physiological fluids and / or tissues. Background of the Invention

[0004] Hydrogels have a wide range of uses in medical applications, including drug delivery platforms, anti-adhesion agents, sealants, space fillers, and organ spacers. Hydrogels based on certain chemistries have gained wide acceptance based on their generally good tolerability and few adverse side effects. Approved products are now on the market.

[0005] Implants that deliver drugs over time at therapeutically effective doses are useful in many areas. In the case of drug delivery, hydrogels can provide the ability to make release profiles within a selected range while providing significant reservoir volumes. Advances in this technology allow the delivery of a variety of drugs with different solubility and stability. Drug delivery systems based on hydrogels provide the ability to make controlled drug release suitable for a range of applications.

[0006] Many hydrogels formed in situ use a two-component system to activate the in situ hydrogel forming reaction after mixing. This provides a discrete starting point and can have the advantage of allowing hydrogels to form quickly and reliably. However, medical uses typically require special delivery catheters, sprayers and other devices, and the two-component characteristics of these systems may make the design, development and use of these delivery systems more complicated. To date, no single-component system has been developed that can provide a reproducible polymerization of a hydrogel system within a convenient and useful time scale in a medical or surgical environment. SUMMARY OF THE INVENTION

[0008] Disclosed are biocompatible cross-linked polymers, preparation methods and uses, wherein a single solution system contains precursors that provide both electrophilic groups and nucleophilic groups that can react in situ and cross-link to form a hydrogel, and the hydrogel is formed in the absence of a separate and different precursor solution. The cross-linking reaction can be carried out in situ after the single mixture is deposited, but the solution including the system is still a water-soluble mixture containing a selected ratio of electrophilic groups and neutral groups before placement in the body. Applications of such biocompatible hydrogels include, for example, the formation of injectable long-acting preparations, space or dermal fillers, and tissue enhancement, expansion and spacing applications, and extraluminal stent placement of lumens (including blood vessels or hollow organs). Additional applications can be used for primary or secondary controlled drug delivery applications for particularly difficult entry placement (currently bulky two-part systems cannot achieve such placement and there is a risk of clogging).

[0009] Provided are compositions, methods and applications for biocompatible in situ hydrogel formation, which are used for medical devices and pharmaceutical applications in the absence of chemical or physical activators. The present invention is based on electrophilic and nucleophilic species co-dissolved into a single working system, wherein the electrophilic species is a macromer, such as a polymer, having a reactive functional group suitable for forming an adduct with an appropriate nucleophilic agent, and the nucleophilic species can be a macromer, such as a polymer, and is an acid conjugated form that can reduce pH when used in an aqueous solution, and the aqueous solution can be unbuffered. Unlike similar existing covalently cross-linked hydrogel systems known in the art, the composition does not require a separate activator or an external activation event to work. The prior art around hydrogel single solution systems requires energy input in the form of radiation or thermal energy to promote crosslinking for in situ hydrogel formation. Dual systems known in the art require mixing of two components, wherein the activator is used in the form of a pH-based accelerator or a free radical initiator for redox reactions. In contrast, the single solution system of the present invention does not involve separation of reactive components, external input from an activation source, or immediate delivery after mixing to form an in situ long-acting preparation. The dissolution of electrophilic species and nucleic acid conjugated species in aqueous solution remains non-reactive until introduced into the body, where the diffusion exchange of the liquid leads to neutralization of the acid conjugated species, resulting in an increase in the local pH at the precursor site, followed by in situ gel formation. A single solution system can include a therapeutic agent to provide additional treatment in combination with the medical device application of the hydrogel, or be used alone as a drug depot capable of local and / or some systemic drug delivery. The therapeutic agent can be included as a low-solubility slow-eluting component or contained in suspended drug delivery particles, which are further encapsulated by the hydrogel. In some embodiments, the same or different types of hydrogels can be used by secondary encapsulation of the hydrogel, resulting in the hydrogel particles being suspended in a single solution system, forming a hydrogel formulation in situ.

[0010] The method for the application of the in situ formation system of a single solution derived from both electrophilic species and nucleic acid conjugated species includes introducing by adopting conventional means of intracavitary delivery. Suitable delivery tools include injection, needle and needleless catheter, sprayer, etc., and these devices include tools known in the art. Advantages of the present invention include no need for mixing and special delivery systems, and allowing multiple injections from the same working system without strict time limits. Different from dual reservoir systems known in the art, the system can be stopped and restarted by intracavitary delivery without blocking the delivery device until the desired application or system is exhausted. The method for the application of a single system in situ hydrogel without an external activator provides the ability to be integrated with a traditional delivery system, while eliminating the complexity in flexibility, availability and accessibility that exists in the prior art.

[0011] The application of a single solution system comprising two reactive precursors that can form a gel without an external or in vivo auxiliary activator required for forming a long-acting preparation is ideal in clinical applications, where the flow of one or more precursor solutions may be restricted, or the area of ​​spread may be limited, such as limited by surrounding tissues / organs / anatomical features. Particularly suitable applications of the compositions of the present invention relate to such procedures, where the gel time can be extended, and the demand for rapid gelation (such as less than 20 seconds) is not critical, and the system does not undergo significant dilution. These uses may include volume increase, such as dermal fillers or eye injections for scleral expansion or placing long-acting preparations in the fornix of the eye. Additional clinical uses may include reinforcement of the inner wall of the cavity surrounding hollow blood vessels and / or organs to prevent the lumen from narrowing and obstruction. In other applications, the lumen can be opened using a standard balloon catheter, and a single system is injected into the wall without the need for accompanying use of an external activator or a dedicated catheter delivery device. This way of opening the lumen may be very useful, for example, in the treatment of benign prostatic hypertrophy (BPH), where narrowing of the urethral lumen may result in limited urine flow. Injection of the single component hydrogel forming precursor into the body of the prostate can be performed, followed by inflation of the intraluminal balloon to shape the urethra in an open, dilated position, as the precursor solidifies within the prostate and "fixes" it in a compressed configuration. Intraprostatic injection can be performed from within the urethral lumen, or it can be performed from a transrectal route, similar to what is done during a prostate biopsy.

[0012] Other applications may include a single solution system as a therapeutic delivery depot, such as in the case of fornix insertion, intraocular injection into the anterior-posterior space, and intratumoral injection of chemotherapy delivery depots where access is difficult or impossible using traditional catheters. Multi-tipped bifurcated needles that allow for circumferential injection within the tumor or even around the lumen are useful delivery systems for such precursors. Other applications may focus on therapeutics where off-target drug applications have side effects, where small-scale repeated injections (i.e., tattoos, Applications for tattoos can provide tattoos that last for a longer but limited period of time, or with non-degradable hydrogels. Other start-stop applications can include multiple needle injections for administration to multiple patients using a single solution that is prepared. Other start-stop applications are unique to single solution systems with acid conjugates that cannot be achieved with two-part systems that require external administration, including nasal administration such as sprays, where both nasal cavities need to be exposed without clogging, or high pressure needle-free injections, where cross-linking initiation prior to entry into the body would prevent skin penetration.

[0013] One particularly desirable application involves filling a patient's fallopian tubes for birth control or other medical purposes. The hydrogel systems described herein are adapted to penetrate well into the complex structure of the fallopian tube walls. The hydrogels can be designed to last for a long period of time, such as at least about 180 days or possibly the patient's lifetime, or for a selected shorter period of time.

[0014] In one aspect, the present invention relates to a medical hydrogel precursor solution comprising a mixture of an aqueous solvent having a pH not exceeding about 6, a first precursor comprising a plurality of electrophilic functional groups and a first hydrophilic core, and a second precursor comprising a plurality of protonated amine groups. Typically, the precursor solution is flowable for at least 10 minutes after formation and gels within 20 minutes after dilution with 1 / 3 volume of 37°C phosphate buffered saline (PBS) (3 volumes of hydrogel precursor solution to 1 volume of PBS).

[0015] In another aspect, the present invention relates to a medical hydrogel precursor solution comprising a mixture of an aqueous solvent having a pH not exceeding about 6, a first precursor comprising a plurality of electrophilic functional groups and a first hydrophilic core, and a second precursor comprising a plurality of protonated amine groups and a second hydrophilic core.

[0016] In another aspect, the present invention relates to a method for delivering an in situ cross-linked medical hydrogel, the method comprising:

[0017] blending an electrophilic precursor and a nucleophilic precursor with an aqueous solvent having a pH of no more than about 6 to form a precursor solution having a storage stability against mobility limitations of at least about 10 minutes at room temperature, the storage stability being determined by the precursor solution being injectable from a 5 ml syringe with a 25 gauge needle; and

[0018] An amount of the precursor solution is delivered to a patient, wherein the precursor solution contacts physiological fluids associated with vital physiological tissue to induce cross-linking of the hydrogel, wherein the hydrogel gels in vivo in no more than about 5 minutes.

[0019] In other aspects, the present invention relates to a method for perfusing an in situ cross-linked hydrogel into a patient's fallopian tube, the method comprising:

[0020] The hydrogel precursor solution is delivered directly into a first fallopian tube of the patient and then into a second fallopian tube of the patient using an applicator, wherein the applicator includes a reservoir of the hydrogel precursor solution connected to a catheter, the catheter being configured to place the hydrogel precursor transcervically within the fallopian tube, and wherein the hydrogel precursor solution includes a mixture of a first compound having a plurality of electrophilic groups, a second compound having a plurality of nucleophilic groups, and an aqueous solvent having a pH of no greater than about 6, wherein the hydrogel precursor solution gels within no more than about 3 minutes of contact with tissue of the first fallopian tube and gels within no more than about 3 minutes of contact with tissue of the second fallopian tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of preparing a single solution system.

[0023] Figure 2 is a schematic diagram of an applicator with a single reservoir for delivering a single solution system.

[0024] Figure 3A is a side view of a delivery system for injecting a single solution in situ cross-linkable precursor to occlude a body lumen.

[0025] Figure 3B yes Figure 3A Cross-sectional view along line AA.

[0026] Figure 4 Shows a method of using Figure 3A A device to block the fallopian tubes.

[0027] Figure 5 is a graph of gelation time and dilution volume as a function of pH for a single solution system with added buffer.

[0028] Details

[0029] Medical hydrogels suitable for in situ formation by covalent cross-linking chemistry have been developed for delivery from a single stable solution. Delivery of hydrogel precursors from a stable single solution provides great convenience for doctors to deliver compositions without strict planning of time limits set by precursor stability, and allows the application of previously unrealistic hydrogels. These systems are designed to contact tissues to achieve gelation processes through pH changes induced by the natural physiological environment without the need to apply additional energy sources or initiating solutions. Therefore, the treatment can be applied conveniently and efficiently without any operation other than delivering the composition. It is advantageous to have a single-component-based formulation that can be delivered by conventional needles and fluid delivery systems that are already widely used in medicine. The composition can be effectively used for a range of applications. A particular application suitable for the hydrogel system described herein involves delivering hydrogels to fill female fallopian tubes. Other applications include, for example, ocular administration for drug delivery, as well as drug delivery for tumor treatment, treatment of BPH, and delivery of therapeutic drugs around blood vessels, but a range of useful applications are described herein. Various applicator designs may be suitable, some of which can be effectively used with one hand.

[0030] Two-component hydrogel systems have found significant applicability for medical applications involving in situ gelation. Commercial products involving in situ gelation include, for example, Skull sealant (Integra Life Systems), Exact Spinal Sealant (Integra Life Systems), SpaceOAR TM (BostonScientific), SpaceOAR TM Vue (Boston Scientific) and Sealant (OcularTherapeutix). Although the two-component hydrogel system works well, the precursors are mixed in the catheter during delivery, and the catheter usually starts to clog in less than a minute. For some applications, the precursors can be mixed in the blood vessel within a specified short time period (such as less than 20 seconds) for administration. For appropriate applications, these are very good conditions, and the hydrogel can gel quickly (in a few seconds or less in some embodiments). For other applications, this time limit may be unrealistic, inconvenient or too expensive because the mixed material needs to be used so quickly that the remaining material cannot usually be delivered to the second location, resulting in material waste.

[0031] Some hydrogels can be initiated with radiation (such as UV or visible light) to provide free radical simulation of the crosslinking process. See, for example, Hubbell et al., entitled "Photopolymerizable Biodegradable Hydrogels as Tissue Contacting Materials and Controlled-Release Carriers (photopolymerizable biodegradable hydrogels as tissue contact materials and controlled release carriers)" U.S. Patent 5,410,016, and Sheikhi et al., entitled "Tough Tissue Sealants and Use Thereof (tough tissue sealants and their uses)" WO2021 / 101983, which are all incorporated herein by reference. Embodiments involving UV light delivery (such as using optical fiber or UV lamp) involve increased time to be crosslinked by radiation, and the cost of equipment for delivering UV light or other radiation. For some applications, due to the timing of crosslinking and the difficulty of directing radiation to the hydrogel precursor, it may be unrealistic to use radiation. The electrophilic-nucleophilic reaction involved in the hydrogel described herein is controlled by pH.

[0032] In order to provide a single applicator delivery of an electrophile-nucleophile mixed precursor system, the technicians strive to fully slow down the gelation time so that the precursors can be mixed immediately before use. Such hydrogel embodiments are described in the published U.S. patent application 2016 / 0331738 (hereinafter referred to as '738 application) entitled "Drug Delivery from Hydrogels" by Jarrett et al., which is incorporated herein by reference. The '738 application teaches adding a buffer to each individual precursor and then mixing. These hydrogels are specifically designed for eye injection, wherein the hydrogel will not significantly migrate during the gelation time, which can be up to 5 minutes, but is generally less than one minute. The delivery reservoir will have a shelf life comparable to the gelation time. These systems will not have the advantages of the hydrogel systems described herein.

[0033] Applicant's pending applications describe a mixture during delivery, which is a mixture of nucleophilic precursors and electrophilic precursors that are subsequently mixed with an activator solution, see U.S. Patent Application No. 17 / 494,752 to Bassett et al., entitled "Transcervical Access Systems For Intrauterine Fluid Exchange, Such As Placement of Hydrogels Formed In Situ" (hereinafter referred to as the '752 application), which is incorporated herein by reference. These systems provide excellent space filling properties with moderate dilution and provide suitably short gelation times. Further developed alternative hydrogel systems described herein avoid the use of an activation solution and can provide a longer shelf life for hydrogel deposition while resulting in slightly longer gelation times and potentially greater sensitivity to dilution effects. Both the current development of the hydrogel system and the embodiments in the '752 application provide significant functionality for their respective appropriate applications.

[0034] A delivery catheter suitable for placement in the fallopian tube is described in U.S. Pat. No. 6,152,943 to Sawhney, entitled "Methods and Apparatus for Intraluminal Deposition of Hydrogels" (hereinafter referred to as the '943 patent), which is incorporated herein by reference. Although other structures may be used, the basic structure of the catheter in the '943 patent and its modifications may be generally desirable for delivering hydrogel precursors into the fallopian tube, with modifications suitable for the reservoir of the present precursor. The '943 patent describes a dual precursor component hydrogel system that is mixed in the catheter during delivery.

[0035] A hydrogel is a material consisting of an insoluble hydrophilic polymer, which, when fully hydrated, consists essentially of water in an insoluble hydrophilic polymer matrix. The hydrogel may include absorbable or non-absorbable materials when in contact with a patient's body fluids, and some hydrogels gradually hydrolyze and decompose when in contact with water or other aqueous solutions. Some hydrogel systems allow the crosslinking process to be controlled by delaying crosslinking until the hydrogel is delivered, for example, because the viscosity of the material flowing through the delivery device increases substantially until the hydrogel precursor mass is in place. Historically, these systems involve the use of an external activation source that serves a dual purpose. First, it allows the hydrogel system to be injectable, where it is activated only after leaving the application device to prevent catheter blockage. Secondly, this allows for working time before the injection event. In these embodiments, activation is typically by using external radiation (such as light) to induce free radical crosslinking or other energy input for thermally activated polymers (such as thermoreversible polymers or heat-induced free radical polymerization). Single systems with external activation sources are clumsy, thereby limiting certain clinical uses where one-handed application or fine dexterity is required, and taking longer program time. Furthermore, the use of single component thermoreversible polymers does not result in hydrogels with mechanical integrity and modulus suitable for many medical device and longer lasting drug delivery applications.

[0036] In the case of a two-component system, mixing of the two solutions occurs such that these solutions are fluid and ready to form a hydrogel in situ when passing through the applicator device. Two-component systems require a mixing and "set and forget" approach. These systems typically rely on mixing at the time of deployment, with the risk of premature clogging of the device complicating placement of the hydrogel, or not being able to re-apply when multiple or re-applications are desired (such as with two fallopian tubes). For proper administration, two-component hydrogel systems based on a polyethylene glycol hydrophilic core have achieved commercial success, such as and Exact (Integra Lifesystems), (Cordis), SpaceOAR TM &SpaceOAR VUE TM (Boston Scientific.

[0037] Hydrogels described herein can be delivered for in situ gelation by less invasive means (such as catheters). Generally, hydrogels can start with a single liquid precursor solution, which can be formed into a gel when in contact with the patient's physiological fluid, which makes it possible to form a hydrogel by neutralizing the acidified amine group (making it available for cross-linking reactions) to balance pH with physiological pH. In the presence of amino acid conjugates, the illustrated NHS-amine cross-linking reaction will not significantly occur in an unbuffered aqueous system, and similar hydrogel systems are also true. Unreacted co-dissolution can be obtained by forming a single solution with electrophilic polymers and nucleophilic polymer acid conjugates in an unbuffered or weakly acidic buffer solution naturally in a lower pH (usually pH 2-5). "Shelf life" or storage stability refers to the amount of time that a single solution remains stable after co-dissolution.

[0038] The hydrogel precursors described herein surprisingly have a shelf life of at least one hour, but they can gel in less than 10 minutes after being delivered to the patient, and in less than one minute in some embodiments. As used herein, storage stability refers to the time from mixing the hydrogel precursor to form a precursor solution ready to be delivered to the patient until the time when the hydrogel is too viscous to the extent that it cannot be effectively delivered due to effective conversion to a non-flowable state. Although the effective delivery of the precursor solution may depend on a specific application, in order to specify the storage stability of the composition of the precursor solution, this can be evaluated according to the injection ability of a 24-gauge needle from a 5ml syringe. These hydrogel precursors generally have an amine with a pH before delivery that is generally no more than 6 pH units and a buffer concentration within the tolerance range or no buffer is added. Dissolved carbon dioxide provides a low amount of carbonic acid, which can be regarded as a baseline rather than an added buffer. Physiological fluids are naturally buffered to explain the overlapping presence of dissolved carbon dioxide, and the presence of dissolved carbon dioxide does not interfere with the performance of the hydrogel. The design of these precursor solutions is generally contrary to the traditional concept that buffer is important for controlling precursor behavior. By formulating the precursor solution with or without added buffer in tolerable amounts, the gel time can be kept at a desired low level by allowing equilibrium to be reached more quickly with the patient's physiological pH (typically about 7.1 and 7.6). The low pH of the precursor solution prior to delivery provides inhibition of significant cross-linking, thereby allowing a longer pot life, which is essentially the time from preparation of the precursor solution until the viscosity becomes high enough to induce occlusion of the delivery catheter.

[0039] Electrophilic precursor components can have suitable functional groups to form hydrogels with crosslinking with amine groups. Crosslinking functional groups are usually suspended on the hydrophilic core (which is usually polymeric) to provide medium molecular weight. Precursors usually have three or more crosslinking groups to provide highly crosslinked hydrogels. Precursors may or may not have degradable functional groups, which can be degraded by hydrolysis, enzymatic or by another biodegradation pathway. Nucleophilic precursors usually contain three or more amine groups, which are usually suspended on the hydrophilic core. The hydrophilic core of the nucleophilic precursor can be polymeric. The amines in the precursors will usually be deprotonated in large quantities under physiological conditions so that the amines can be used for crosslinking. Protonated amines are protected from crosslinking by the acidification of amines, which stabilizes the precursor solution. The ability to rapidly deprotonate under physiological conditions allows rapid crosslinking in the absence of alkaline buffers.

[0040] The single solution system described herein can be used to create permanent or temporary blockage in the fallopian tubes, such as for the purpose of preventing pregnancy. The single solution hydrogel system overcomes the limitations of other pregnancy prevention methods targeting the fallopian tubes. One such method is to permanently implant a metal coil device into the fallopian tubes. After insertion, this device plus associated scar tissue will cause fallopian tube blockage and permanent sterilization. One such device is used to It is reported that The devices have serious side effects, including headaches, bleeding, allergic reactions, persistent pain, holes in the uterus or fallopian tubes, and migration of the device from the fallopian tubes into the pelvis or abdomen. As reported by the FDA, Sales of the silicone tubal embolization system were discontinued in the United States in 2019. Other methods of attempting female sterilization include forming a silicone tubal plug by injecting liquid silicone into the fallopian tubes via a hysteroscope. This procedure requires that a precise amount of catalyst be mixed with the liquid silicone during a specific time period prior to injection. In practice, the hysteroscope must be carefully placed and aligned before the catalyst is added. This procedure is subject to high failure rates in embolization placement and retention, as well as reactions with silicone. It is theorized that one aspect of the high failure rate of silicone embolization systems is due to the mismatch between the hydrophobic silicone and the hydrophilic tissue of the fallopian tube (not allowing access to the folds and crevices present in the fallopian tube). Silicone in situ embolization has been clinically tested in the United States and has been sold in Europe. Preformed silicone embolizations were briefly sold under the trade name Adiana, but sales were discontinued a few years later due to a variety of problems. The single solution system disclosed herein is hydrophilic and forms a hydrophilic plug that should be firmly retained. The use of hydrogel polymers with a long history of successful implantation should avoid the problems that exist with other polymer systems.

[0041] Antitumor drugs may be toxic to normal tissues, so the delivery of antitumor drugs may be complicated in delivering the required dose to the tumor without producing toxic levels to surrounding tissues. In experiments using hydrogels as drug delivery matrices in long-acting preparations implanted in tumors, improvements in drug therapy have been proposed. For example, 5-fluorouracil was loaded into PEG-based polymers and tested in mice for induced tumors of human non-small cell lung adenocarcinoma, and the results were encouraging. See Yi et al. "Pharmacokinetic properties and antitumor efficacy of the 5-fluorouracil loaded PEG-hydrogel (5-fluorouracil loaded PEG hydrogel pharmacokinetic properties and antitumor efficacy), " BMC Cancer 2010, 10: 211, which is incorporated herein by reference. Similarly, to investigate avoiding drug elution in intratumoral drug delivery, phosphor BODIPY was loaded into microspheres, which were then placed into a hydrogel matrix for delivery to tumors associated with glioblastoma multiforme (GBM), and encouraging results for drug delivery were observed. See "Intratumoral injection of hydrogel-embedded nanoparticles enhances retention in glioblastoma," by Brachi et al. Nanoscale. 2020 Dec 14; 12(46): 23838–23850, which is incorporated herein by reference. The hydrogel system described herein is well suited for drug delivery and provides the opportunity for in situ hydrogel formation, which can facilitate delivery into tumors with greater permeability. Extensive experience with drug delivery based on two-component hydrogels can be adapted to the present one-component system (with the ability to influence drug release profiles).

[0042] Hydrogel has been developed to be effective for ocular applications. Hydrogel can effectively replace drops for drug delivery (with consistent effect). The amount usually used is very small, which can make the more conventional use of low-cost eye drugs, which is too expensive for the two-component hydrogel with a very short time window for delivery. Using the hydrogel system described herein to deliver drugs, a single batch of prepared drug-loaded hydrogels can be used for multiple patients to share costs within the applicable period of the sample, thereby providing improved and cost-effective treatment. The drug-loaded hydrogel applied to the patient's eyes can spread and cover the eye surface or other target eye positions where the hydrogel is formed by cross-linking, thereby providing a timed release drug to the eyes. Hydrogel drug delivery can generally provide a more uniform sustained release than drops, which may be particularly advantageous for some applications. For example, this can be effectively used to deliver, for example, steroids, antibiotics, glaucoma drugs, other suitable eye drugs or combinations thereof after eye surgery as the patient completes the procedure. This model can be suitable for other low-cost, higher-capacity situations where the hydrogel system can provide the desired results. In addition, relative to other long-acting preparations for drug delivery, such as preformed intra-lacrimal inserts, long-acting preparations based on original single components can be placed by smaller lumens and usually in larger quantities without pre-expanding the lacrimal sphincter. These long-acting preparations can also be put into the fornix of the eye with a thin blunt cannula, thereby forming a larger long-acting preparation to be delivered to the eye surface. Relative to preformed long-acting preparations, such a delivery system allows the use of a wider range of drugs (which may be less effective) due to its larger capacity.

[0043] The hydrogels described herein can be suitable for cosmetic applications, such as dermal fillers for wrinkle removal, etc. In addition, hydrogels with suitable dyes can be used for tattoo formation. The resulting tattoo can be durable or designed to be absorbed and removed in a selected time window. The dye can be bonded to the hydrogel so that the visual effect can last for the same period of time as the hydrogel. Compared with the pigments of traditional tattoos, the use of dyes provides greater flexibility in visual effects. Therefore, fluorescent dyes can be particularly visible under certain lighting (such as blue light, black light or UV light). Typically, vivid images can be formed, wherein these images are not permanent, but can last for a considerable period of time such as months or longer, or possibly a shorter period of time such as days.

[0044] Typically, the in situ hydrogel herein does not involve the process of mixing hydrophilic reactive precursor species with nucleophilic functional groups and hydrophilic reactive precursor species with electrophilic functional groups when delivering. On the contrary, the reactive precursor species containing acid conjugates are co-dissolved in aqueous reagents at appropriate pH, so that the acid conjugates of amines provide sufficient pH inhibition activity to limit the reaction in the precursor solution. After being deployed in vivo, the in situ covalent cross-linking of gel is promoted without mixing with activator solution (e.g., high pH accelerator) or external activator (e.g., light). In some embodiments, the molecular weight of the nucleophilic precursor of acid conjugation is not significantly less than that of the electrophilic precursor and can be the same Mw or greater. In the embodiment where small molecular weight amines (such as lysine and trilysine) are used, in the absence of mixing external accelerators, acid conjugates are usually slow or difficult to deprotonate, although for some applications where slower gelation is acceptable, these small molecule acid conjugates can be used. Small amine acid conjugates also tend to have a short shelf life, so this provides another limitation for their availability.

[0045] Relative to currently available hydrogels, the hydrogel systems described herein can provide improved delivery for certain applications. These hydrogels can be effectively used for space filling, tissue protection, drug delivery and other suitable medical applications. Generally, hydrogels are convenient and easy to deliver.

[0046] Hydrogel systems and applicators

[0047] Typically, at the beginning of a procedure or series of procedures, the electrophilic precursor and the nucleophilic precursor are mixed with a solvent and placed in a suitable dispenser / applicator, such as Figure 1 Various suitable procedures may be used for this formation of the precursor solution, and the choice of process may be made based on the convenience of the user. If the solvent is combined with the precursor directly in the applicator / dispenser, the step of transfer to application may be avoided, but the applicator should accordingly be suitable for mixing directly in the applicator / dispenser.

[0048] In order to form a solution in the distributor, electrophilic precursor 102 and nucleophilic precursor 104 are added to the distributor 108. Electrophilic precursor 102 and nucleophilic precursor 104 are generally solid at room temperature, but in principle, at least one precursor can be a room temperature liquid. Two precursors can be provided as dry powder blends, so that the formation of a precursor solution involves adding a solvent without the step of mixing the separated precursors. In order to form a precursor solution 107, an aqueous solvent 106 is added to the precursor in the distributor 108, and the solution is mixed until the electrophilic precursor 102 and the nucleophilic precursor 104 are dissolved. In some embodiments, the separated precursors can be transported in an aqueous solution, but the transportation of the precursor without solvent usually provides convenience, is easy to package and simplifies sterilization. In some embodiments, dissolution can be determined by the absence of visible particles. Generally, suitable mixing can be performed by manual shaking. In some embodiments, dissolution occurs in less than 5 seconds, about 5 to 15 seconds, no more than 20 seconds, no more than 30 seconds, no more than 1 minute, no more than 5 minutes or no more than 15 minutes. It will be appreciated by one of ordinary skill in the art that additional ranges of dissolution times within the above explicit ranges are contemplated and are within the scope of the present disclosure. If the electrophilic precursor 102 and / or the nucleophilic precursor 104 are solid at room temperature, a consistent low dissolution time can be obtained by adding one or more precursors as a powder (e.g., a fine flowable powder) to a dispenser because a high surface area facilitates dissolution. The dispenser 108 can be a syringe or any other suitable device used when delivering a single solution system, such as a dropper or a catheter with a reservoir for appropriate application. Alternatively, the solutions can be mixed in separate containers and drawn into the dispenser, such as by drawing the mixed solution into a syringe.

[0049] In some embodiments, the syringe barrel can be pre-filled with electrophilic precursor 102 and nucleophilic precursor 104, and aqueous solvent 106 can be sucked into the syringe with a needle or catheter. In other embodiments, the syringe barrel can have a volume capacity greater than the volume of the solution to provide enough head space for mixing the solution by shaking, rotating, tilting or similarly mixing the syringe barrel. In some embodiments, the volume capacity of the syringe barrel can be about 1.25 to about 2.5 times the volume of the aqueous solvent 106, and in further embodiments, about 1.5 to about 2.25 times the volume of the aqueous solvent. It will be appreciated by those of ordinary skill in the art that additional ranges of relative volumes within the above-mentioned clear volumes are contemplated, and such additional ranges are within the scope of the present disclosure.

[0050] In other embodiments, the aqueous solvent 106 is first added to the dispenser 108, and then the electrophilic precursor 102 and the nucleophilic precursor 104 are added to the dispenser 108 and mixed to form a single solution system. For example, the electrophilic precursor 102 and the nucleophilic precursor 104 can be provided as a dry powder blend. Alternatively, the aqueous solvent 106 of the first part is added to the electrophilic precursor 102 to form a first precursor solution in a first container, and the aqueous solvent 106 of the second part is added to the nucleophilic precursor 104 to form a second solution in a second container. The first precursor solution and the second precursor solution can be stored. Before use, the first precursor solution and the second precursor solution can be mixed in the dispenser 108 to form a single solution system. Generally, any reasonable mixing order can be used to form a solution for delivering the precursor to the patient. In some embodiments, the electrophilic precursor 102 and / or the nucleophilic precursor 104 are independently a mixture of precursors with different chemical compositions or chemical structures. The differences may include the chemical composition of the core, the molecular weight of the core, the degree of branching of the core, the number of arms, the average molecular weight of the arms, the functional groups, the degree of functionalization of the arms, etc. The aqueous solvent 106 is preferably an unbuffered medium.

[0051] In some embodiments, aqueous solvent 106 is purified water / sterile water (e.g., water for injection), unbuffered saline or any physiologically acceptable aqueous solution with appropriate buffering capacity. The selection of fluid may be affected by specific applications, but sterile saline for intravenous injection (normal saline) is usually easy to obtain by medical practitioners and is safe for most or all uses. In particular, sterile saline for intravenous injection is usually about 0.9 wt % NaCl per volume or equivalently expressed as 9.0 g NaCl / liter. The effect of buffer may be complicated and depends on both pKa and concentration. In addition, many suitable physiological buffers can be multi-proton, which further complicates their effect. The buffer problem will be discussed further below, but for most applications, in the absence of added buffer, the desired result can be achieved. The polymer solid content of the precursor solution is usually no more than about 30 wt %, no more than about 27 wt % in further embodiments, about 1 wt % to about 25 wt % in additional embodiments, and about 2.5 wt % to about 23 wt % in other embodiments, and about 5 wt % to about 22 wt % in some embodiments. The polymer solids content can be considered as a weight determined according to the components added. A polymer solids content that is too low may result in an undesirable dilution effect (which may slow gelation), and a polymer solids content that is too high may result in slower gelation due to slower deprotonation of the amine. The characteristics of the precursor may also affect the selection of the polymer solids content value. It will be appreciated by one of ordinary skill in the art that additional ranges of polymer solids content within the above explicit ranges are contemplated and are within the scope of the present disclosure.

[0052] Once the precursors are mixed into a single solution, the time can be recorded to provide a window for targeted delivery of the hydrogel before the precursor batch expires. The time window is related to storage stability, although practical considerations may dictate that the time window be set slightly shorter than storage stability to provide an additional safety margin in the event that the time window is not strictly adhered to. During this time window, one or more hydrogel delivery procedures may be performed. The actual time window may also be affected by the mode of delivery used for a particular application.

[0053] Storage stability can be evaluated in vitro as the characteristic of precursor solution. Specifically, storage stability can be such a time, during which the precursor solution is delivered using the delivery mode specified for application, and gelation (unless otherwise explicitly stated) is carried out in an acceptable time after being delivered to the physiological solution. In some embodiments, it is expected that some crosslinking will occur before the storage stability time period ends, but the crosslinking during gelation is significantly less. In some embodiments, some hydrolysis may occur before delivery, and the hydrolysis of electrophilic esters may occur during storage, and because the crosslinking group is removed by hydrolysis, it can be observed that the gel time after delivery is extended. Generally, storage stability is at least about 10 minutes, at least about 15 minutes in other embodiments, about 20 minutes to about 2 days in other embodiments, about 30 minutes to about 10 hours in some embodiments, about 45 minutes to about 8 hours in further embodiments, and about 1 hour to about 6 hours in other embodiments. Another time parameter is gel time, which is such a time, during which the precursor is fully crosslinked to no longer flow, and for convenience, gel time can be measured in vitro. Complete cross-linking may require significantly longer time, but once gelation occurs, the hydrogel is usually fixed in its deposition position. Gel time is generally expected to be shorter. In some embodiments, the gel time is no more than 10 minutes, no more than 5 minutes in further embodiments, no more than 3 minutes in other embodiments, no more than about 2 minutes in some embodiments, about 2 seconds to about 90 seconds in other embodiments, and about 10 seconds to about 60 seconds in further embodiments, but generally, an upper limit cutoff value can be selected for a specific application, such as 5 seconds or 10 seconds to 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds or 110 seconds. Gel time is measured in vitro by the following method: a certain volume of precursor solution at room temperature is injected into phosphate buffered saline (PBS) at 1 / 3 volume at 37°C, the combined volume is maintained at 37°C, and the time to form a solid or semi-solid substance is recorded, wherein the volume of the precursor solution and the volume of PBS are equal. In other words, a volume of the precursor solution is injected (combined) with 1 / 3 the volume of PBS relative to the precursor solution. The PBS is standard PBS having a pH of about 7.4 and for clarity is considered to have 1.37 millimolar (mM) NaCl, 2.7 mM KCl, 10 (8) mM Na2HPO4, 1.8 (2.0) mM KH2PO4. One of ordinary skill in the art will recognize that additional ranges of gel times and storage stability times within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0054] With regard to buffers, whether or not the hydrogel precursor changes pH is not considered a buffer and in principle can provide some buffering function. Typically, dissolved carbon dioxide is present and this is not considered an added buffer and the observation is that the carbon dioxide acts as a baseline. The amine precursor is provided in an acidified form where the acidic protons act as protecting groups that block crosslinking. Of course, the acidification is at equilibrium in solution. Upon contact with body fluids at physiological pH, the acidified amine can be neutralized so that it can crosslink with the electrophilic precursor at an appropriate rate. The precursor solution should generally have no additional buffering capacity or an appropriate buffering capacity. A buffer can be considered as any Bronsted base, which will generally be an anion (B) corresponding to a weak acid (HB). - ), is in equilibrium with the corresponding weak acid. Anions corresponding to strong acids, such as halide anions, do not act as buffers. If the precursor solution has an increased buffering capacity, it may shorten the shelf life and / or extend the gelation time, but such an effect may be within a tolerable range. The effect of the buffer depends on pKa and concentration. Although it is generally desirable to have no added buffer except for the contribution of impurities and dissolved carbon dioxide in the precursor solution, an appropriate concentration of a properly added buffer is generally acceptable for at least some applications. Due to these complexities, suitable buffers and concentrations can be evaluated based on storage stability and gel time. For many applications, a storage stability of at least about 10 minutes and a gel time of no more than 2 minutes provide a reasonable window for buffer evaluation, but other limits within the generally discussed range of these parameters can be used if necessary.

[0055] There are a variety of procedures that may benefit from the use of the single solution systems described herein. In general, the single solution systems are particularly useful for delivery to locations where placement requires a period of time to properly place, such as those locations where existing two-component hydrogels may clog the applicator / dispenser before delivery is complete, or where multiple delivery locations involve a period of time that is not suitable for complete delivery using the two-component system without the use of multiple applicators, or where multiple deliveries involve a period of time where aliquots of a prepared single solution system are delivered to multiple patients. Specific applications discussed below include tubal ligation and drug delivery. For tubal applications, Figure 2 The syringe can be attached to an appropriate catheter, as described below. With respect to drug delivery, specific applications may involve anti-neoplastic drugs or ophthalmic applications. For anti-neoplastic drug placement, proper placement may involve a considerable period of time, and for ophthalmic drug delivery, a single applicator / dispenser can be used for multiple patients in an appropriate setting, with due consideration for sterilization or disposal of necessary components between patients.

[0056] Figure 2A dispenser suitable for delivering a single solution system described herein is shown. In this embodiment, dispenser 200 includes a syringe 202 with a connector 203 (such as a standard Luer lock connector). Connector 203 is connected to a catheter 204 with a distal end 206 and a delivery tip 208. Basic dispenser 200 also has a plunger 210, which is attached to a plunger seal 212. Plunger seal 212 contacts the solution 214 in syringe 202. The delivery of solution 214 through delivery tip 208 can be controlled by pressing plunger 210. In some embodiments, catheter 204 can be a needle or catheter. In some embodiments, delivery tip 208 has one or more side ports, open distal ports, or a combination thereof. There is no particular limitation on the dispenser for a single solution system, and commercially available applicators are included. In some embodiments, if desired, an applicator designed for a more complex system (such as a dual solution system) can be used.

[0057] Figure 2 The applicator of the invention can be effectively used for a range of applications. The catheter 204 can be a general-purpose catheter or needle, or can be specially modified to facilitate a particular procedure. A specific catheter for delivery to a fallopian tube or similar lumen in a patient's body will be described below. The applicator for the hydrogel precursor can have an alternative design that may be more suitable for a particular application (whether or not it can be used) Figure 2 of the allocator).

[0058] In the basic formula of precursor solution, nucleophilic precursor and electrophilic precursor provide cross-linking functional group, hydrophilic core (for providing general hydrogel characteristics) and optional additional functional group (provided for hydrogel degradation after delivery). The specific properties of the details of the precursor control the obtained hydrogel, and its delivery is controlled by the basic characteristics of the delivery system as described in detail in this section. For some applications, it may be desirable to have such a hydrogel, which degrades in an appropriate time period, and functional groups can be selected to adjust the degradation time (such as using the hydrolyzable functional groups appropriately selected) with a certain interval size. In other applications, it may be desirable to use a more lasting hydrogel, which may only slowly degrade or not degrade at all. These lasting hydrogels may be desirable for delivery to the fallopian tube. The following provides additional details of the precursor.

[0059] Hydrogel system with chemical crosslinking

[0060] The hydrogel system providing the desired medical function described herein is provided with a single solution, which is formulated to provide the required precursor solution within a time window. The hydrogel precursor can be designed to spontaneously crosslink based on nucleophilic-electrophile reactions when in contact with a physiological solution (such as lymph, blood, tissue fluid, other body fluids, etc.) or a similar aqueous solution. Through the appropriate design of the hydrogel system, the precursor can be designed so that these precursors are merged into a solution, which remains stable within the desired time range to complete a procedure or a series of procedures, while allowing rapid crosslinking after delivery.

[0061] Therefore, the first aspect of the design of the polymer system is to form a suitably stable initial blend of precursors. Although the polymer precursors should be suitably stable to not significantly crosslink before delivery, the solution should result in reasonably rapid crosslinking after contact with physiological conditions. The basic chemical structures of the hydrogels and precursors will be described next in conjunction with their properties, and the hydrogel properties are described in more detail below.

[0062] As mentioned above, the precursor generally includes at least two different polymerizable compounds, but the precursor solution may include more than one electrophilic precursor and / or more than one amine precursor. In order to form a highly cross-linked hydrogel, the precursor generally has more than two reactive functional groups for forming crosslinks. In some embodiments, each precursor compound generally has a medium molecular weight and may include a polymer portion. If functionality>2 (i.e., a cross-linked network is formed during polymerization) and the water-soluble polymerizable monomers forming the hydrogel have at least a medium molecular weight and / or a polymer portion in its core, they may be referred to as macromonomers in this article. The molecular weight range will be discussed further below. The functional groups of the precursor provide for cross-linking reactions and biodegradable features (if present) and the overall properties of the precursor solution and the product hydrogel.

[0063] Typically, pH is used to control the cross-linking reaction. Therefore, avoiding the added buffer in the precursor solution allows for faster pH adjustment when in contact with a fluid having a physiological pH, which can increase the pH to allow the cross-linking reaction to proceed, usually at a fast rate, even without using an accelerator solution. Some appropriately selected buffers can be added to the solution, wherein the gel time has a certain increase, which may be acceptable in some cases, and in some embodiments, may be desirable, such as dermal fillers that can be repositioned before gelation after delivery. In any case, contact with a liquid at a physiological pH can cause the pH of the precursor solution to increase, which deprotonates the amine groups and thus provides a promotion to the cross-linking reaction. The diffusion that leads to the equilibrium of pH can occur quickly for the precursor solution, and due to the mixture of precursor molecules, longer distances of macromolecular diffusion may not be required to form a highly cross-linked hydrogel. Amine precursors are selected to be deprotonated in large quantities at physiological pH, and the macromolecular precursors described herein provide this feature. After the gel time has passed, further cross-linking occurs in an additional time period.

[0064] Suitable functional groups for crosslinking macromers to form tissue implants in situ may also be advantageously used in hydrogel systems, including macromers containing electrophilic groups that are active with amine functional groups. Thus, multi-component hydrogel systems can spontaneously crosslink when the components are activated by contact with physiological fluids, but two or more components are suitably stable for a reasonable process time prior to activation by physiological fluids. Such systems include, for example, monomers (such as macromers) that are difunctional or polyfunctional amines in one component and macromers with difunctional or polyfunctional electrophilic groups (such as N-succinimidyl-containing moieties) in another component. Succinimidyl functional groups facilitate amide bond formation in reactions with amines and have been used in other medical hydrogels, but other suitable electrophilic precursors are described below.

[0065] The hydrogel precursor may have crosslinks that are activated by physiological fluids in contact with the precursor after delivery. The hydrogel precursors described herein may be designed to be dilution resistant if formed with sufficient solid content. The hydrogel and precursor solution properties will be further described below. Parameters that affect performance include: functional group chemistry, crosslink density / molecular weight of monomers, monomer composition, percent solids in the hydrogel precursor, and ionic strength.

[0066] The cross-linking density of the obtained biocompatible cross-linked polymer is controlled by the overall molecular weight of the macromonomer and the quantity of the functional groups available for each molecule.Compared with a relatively high molecular weight (such as 10,000), the relatively low molecular weight (such as 600) between cross-linking will produce a significantly higher cross-linking density.The macromonomer of higher molecular weight provides the gelation time of expectation, and in some embodiments exceeds 3000Da, to obtain elastic gel.In certain embodiments, the polymer of the nucleic acid conjugation is not significantly less than electrophilic polymer in terms of molecular weight.In some embodiments, it is the same size or larger size.

[0067] The cross-linking density can also be controlled by the total solid percentage of the cross-linking agent and the functional polymer solution. In a two-component hydrogel system, increasing the solid percentage in the formulation of the precursor increases the probability that the electrophilic functional group will bind to the nucleophilic functional group before being deactivated by hydrolysis. Surprisingly, some embodiments of the single solution system exhibit different behaviors. In particular, it has been observed that a higher solid percentage may be inversely proportional to the probability that the electrophilic functional group reacts with the nucleophilic functional group, which may be due to the slower deprotonation of the amine (but not wishing to be limited by theory). A single solution system with 25-30% solids can have a significantly longer gel time than a single solution system with 10-15% solids. The range of solid concentrations is given in the discussion of the precursor solution above. Although not wishing to be limited by theory, it is believed that the longer gel time is related to the slower diffusion of physiological fluids into the solution placed in situ with a higher solid percentage and / or the slower diffusion of acid conjugate species from the solution placed in situ. Another method of controlling the cross-linking density is by adjusting the stoichiometry of the nucleophilic functional group and the electrophilic functional group. A one to one ratio results in the highest cross-link density.

[0068] monomer

[0069] Monomers that can be cross-linked to form biocompatible implants can be used. As mentioned above, monomers can be macromonomers, which can be polymers or can be not polymers. As used herein, the term "polymer" refers to a molecule formed by at least three repeating groups. Typically, the term "reactive precursor species" refers to a polymer, functional polymer, macromolecule or micromolecule that can participate in the reaction to form a network of cross-linked molecules (e.g., hydrogels). As mentioned above, in order to form a stable one-component hydrogel precursor system, monomers are typically macromonomers, as described below.

[0070] Monomers may include biodegradable, water-soluble macromonomers such as those described in U.S. Pat. No. 7,332,566 to Pathak et al., entitled "Biocompatible Crosslinked Polymers With Visualization Agents" (hereinafter referred to as the '566 patent), which is incorporated herein by reference. These monomers are characterized by having at least two polymerizable groups and may or may not be separated by at least one degradable region. When polymerized in aqueous solution, they form consistent gels that persist indefinitely or until eliminated by biodegradation. Typically, the macromonomers form a core of a water-soluble and biocompatible polymer, such as a polyalkylene oxide, such as polyethylene glycol, which may be flanked by hydroxy-carboxylic acids (such as lactic acid) to form degradable esters or non-degradable amides. Suitable monomers (in addition to being biocompatible and nontoxic) may also have at least some elasticity after crosslinking or curing, and in some embodiments are degradable. For electrophilic compounds or compounds with amine groups, the core of these compounds may have multiple arms or branches, each with a functional group suitable for crosslinking. As mentioned above, polyethylene glycol (PEG) based monomers are established hydrogel precursors, and precursor compounds are commercially available.

[0071] Nucleophilic functional groups are usually amine groups. Amine groups can be protonated as protecting groups or gated to control crosslinking. The nucleophilic amine groups of the precursor can be designed to be significantly deprotonated at physiological pH values ​​(such as from about 7.1 to about 7.6 pH units), although the blood and tissues of healthy individuals are generally in a narrower pH range. In some embodiments, polymers can have biodegradable parts or bonds in a hydrolytic manner, such as esters, carbonates or other suitable bonds. Several such bonds are known in the art and are derived from alpha-hydroxy acids, their cyclic dimers or other chemical species for synthesizing biodegradable products, such as glycolide, dl-lactide, l-lactide, caprolactone, dioxanone, trimethylene carbonate or their copolymers.

[0072] Typically, monomers that provide electrophilic functional groups and monomers that provide amine groups are macromonomers. Macromonomers typically have a biologically inert and water-soluble core (with pendant reactive functional groups for crosslinking). When the core is a water-soluble polymer region, the polymer that can be used can be a natural or synthetic polymer. Suitable polymers for the core can include polyethers, such as polyalkylene oxides such as polyethylene glycol ("PEG"), polyethylene oxide ("PEO"), polyethylene oxide-co-polypropylene oxide ("PPO"), co-polyethylene oxide block or random copolymers, poloxamers, such as F-127; and polyvinyl alcohol ("PVA"); poly(vinyl pyrrolidone) ("PVP"); polylactic acid ("PLA"); and polysaccharides such as hyaluronic acid, chitosan, dextran or cellulose and their derivatives. Based on extensive experience in existing medical products, polyethers and more particularly polyethylene glycol (also known as poly(oxyalkylene) or poly(ethylene glycol)) are particularly suitable.

[0073] Smaller molecular weight polyamines have been successfully used in two-component polyethylene glycol-based hydrogels for medical applications. In particular, trilysine has been used. As seen in the following examples, trilysine can be used in a single solution form, but has a shorter shelf life and a longer gel time. Nevertheless, for some embodiments, these embodiments may be useful, especially in a buffer-free system. Specific small molecule amines include, for example, lysine, dilysine, trilysine, tetralysine, pentalysine and mixtures thereof. The molecular weight of the smaller molecular weight polyamine can typically be 200 to about 1800, in further embodiments, about 225 to about 1650, and in additional embodiments, about 250 to about 1500. It will be appreciated by those of ordinary skill in the art that additional molecular weight ranges for lower molecular weight polyamines within the above-defined ranges are contemplated and are within the scope of the present disclosure.

[0074] It has been determined that hydrogels formed by macromers with longer distances between crosslinks are generally softer, more compliant and more elastic. Therefore, in the polymers of the '566 patent, the increase in the length of the water-soluble segments (such as polyethylene glycol) tends to enhance elasticity. As used herein, the molecular weight of hydrophilic macromers (such as macromers with a polyethylene glycol macromer core) is generally at least about 2,000, in some embodiments about 5,000 to about 500,000, in further embodiments about 7500 to about 100,000, in additional embodiments about 10,000 to about 50,000, and in other embodiments about 15,000 to about 40,000. As used herein, molecular weight (mass) is in conventional units, which can be equivalent to daltons or molar mass-grams / mole (assuming that natural isotopes exist in either case), and for polymers, if there is any distribution of molecular weight, the molecular weight is generally reported as an average value. One of ordinary skill in the art will recognize that additional ranges within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0075] The hydrogel precursor in the hydrogel precursor solution has a ratio of electrophilic functional groups to amine functional groups. The ratio of functional groups can change the crosslinking density and properties of the resulting hydrogel. Generally, if the number of electrophilic functional groups and amines is one to one, the hydrogel can be completely crosslinked if there is enough time and no restrictions. Generally, the ratio of electrophilic groups to nucleophilic groups can be about 0.8 to 1.2, and in further embodiments, about 0.9 to about 1.1, and in further embodiments, about 0.95 to about 1.05, but the ratio can be about 1: 1. It will be appreciated by those of ordinary skill in the art that additional ratio ranges within the above-defined ranges are contemplated and are within the scope of the present disclosure.

[0076] In order to achieve the desired functional group ratio, functional groups can be distributed in various ways. The side hanging functional groups extending from the core can be referred to as being associated with the arms of the precursor. The precursor generally has 2, 3, 4, 5, 6, 7, 8, 9, 10 or more arms. At least one precursor has at least 3 arms to obtain crosslinking, and precursors of 4, 6 or 8 arms can be conveniently used to obtain the desired hydrogel properties. In order to obtain a one-to-one functional group ratio, if the precursor has the same number of arms, an equimolar amount of precursor can be used, or if there are different numbers of arms on the corresponding precursor, the molar ratio can be adjusted accordingly. Therefore, a 4-arm precursor with twice the molar amount can be combined with an 8-arm precursor to obtain a 1:1 functional group ratio. For weight ratio, the molar ratio can be adjusted accordingly based on relative weight, and for a precursor of 8-arm 10K MW (molecular weight of 10,000), it is combined with a 8-arm 20KMW precursor of twice the mass to obtain a 1:1 functional group ratio. One of ordinary skill in the art can adjust these calculations to obtain different quantitative ratios for the functional groups.

[0077] Functional groups and cross-linking reactions

[0078] Cross-linking reactions are usually designed to occur in aqueous solutions (surrounded by physiological conditions) in vivo, where the hydrogel reaction occurs in a transient local environment. Therefore, cross-linking reactions occur "in situ", which means that they occur at local sites, such as organs or tissues in living animals or humans. Due to the in situ nature of the reaction, the cross-linking reaction can be designed not to release an undesirable amount of polymerization heat. The gelation time of the desired procedure is as described above, and complete cross-linking is usually completed after 15 minutes to 24 hours, but other times outside this range are also acceptable. Certain functional groups such as alcohols or carboxylic acids usually do not react with other functional groups (such as amines) at physiologically acceptable pH (e.g., pH 7.2-11.0, 37° C.). However, such functional groups can be made more reactive by using activating groups (such as N-hydroxysuccinimide or its derivatives). In general, a variety of methods for activating such functional groups are known in the art. Suitable activating groups include, for example, carbonyldiimidazole, sulfonyl chloride, chlorocarbonate, aryl halide, sulfosuccinimide ester, N-hydroxysuccinimide ester (NHS), succinimide ester, succinimide amide, epoxide, aldehyde, maleimide, imidoester, etc. N-hydroxysuccinimide ester or N-hydroxysulfosuccinimide groups are desirable groups for crosslinking amine-functionalized polymers such as amino-terminated polyethylene glycol ("APEG") because of their long-standing use in approved products and acceptance in medical implants.

[0079] Suitable nucleophilic functional groups are polymers with primary amines conjugated to acids. Therefore, another functional group for cross-linking is generally an amine. Amines are weak bases, and the pKa of protonated amines depends on the molecule. In some embodiments, the acid conjugate is HCl, and HCl-salified PEG amines are formed. The acid conjugate can be selected to match the molar concentration of the amine. The advantage of the NHS-amine reaction is that the reaction kinetics leads to rapid gelation, usually within about 10 minutes, more usually within about 1 minute, and most usually within about 30 seconds. Ultrafast gelation applications with gelation of about 5 seconds or less are generally not suitable for in-situ reactions with the precursors described herein. On the contrary, applications with confined spaces (such as subcutaneous or along the surface) generally obtain desired results.

[0080] Protonated amines are generally not amenable to nucleophilic substitution. Therefore, the precursor solution can be prepared at an appropriate pH to maintain substantially protonated amines prior to delivery to contact with physiological fluids. Such preparation can keep the precursor solution from premature crosslinking.

[0081] The cross-linking density of the resulting biocompatible cross-linked hydrogel is controlled by the overall molecular weight of the monomers and the number of functional groups available per molecule. A lower molecular weight (such as 2000 Da) between cross-links will produce a higher cross-linking density than a higher molecular weight (such as 100,000 Da). A higher molecular weight monomer can be used to obtain a more elastic hydrogel, and correspondingly, a lower molecular weight monomer can be used to obtain a less elastic hydrogel. Different applications may indicate different properties of the hydrogel.

[0082] Cross-link density can also be controlled to a certain extent by the total solid percentage of the monomer in the precursor solution. Increasing the solid percentage will increase the possibility of the electrophilic functional group combining with the nucleophilic functional group before being deactivated by hydrolysis. Another method of controlling cross-link density is by adjusting the stoichiometry of the nucleophilic functional group and the electrophilic functional group. A one-to-one ratio leads to the highest cross-link density. Typically, over time, the hydrogel completes solidification so that the available cross-linking sites form cross-linking bonds. If one or more electrophilic precursors and one or more nucleophilic precursors are provided in equal equivalents, it can be expected that almost all functional groups form cross-linking bonds after complete solidification. Two types of reagents of equal quantity (or reaction equivalent) provide the highest cross-link density. If different functional group ratios are used, the characteristics of the cured hydrogel may be slightly different accordingly. The cross-link density may depend on the number of functional groups on the precursor molecule and the ratio of the precursor molecule. If necessary, the non-stoichiometric ratio of electrophilic groups and nucleophilic groups can be used to change the cross-link density. In some embodiments, the ratio of electrophilic functional groups to nucleophilic functional groups can be 0.8:1.0 to 1.0:0.8. One of ordinary skill in the art will recognize that additional ranges within these explicit ranges are contemplated and are within the scope of the present disclosure.

[0083] Degradable or non-degradable bonds

[0084] Depending on the application, it may be desirable or undesirable that the hydrogel is degradable, such as by hydrolysis or due to enzymatic activity and biodegradable. If it is desired that the biocompatible cross-linked hydrogel polymer is degradable or absorbable, one or more precursors with degradable bonds present between functional groups can be used. As used in the art, if the absorbable polymer is absorbed under physiological conditions, whether or not they are degraded by biological action (such as enzymatic cleavage), they can be called biodegradable. Degradable bonds can optionally also be used as a part of the water-soluble core of one or more precursors in the precursor. Alternatively, or additionally, the functional groups of the precursor can be selected so that the product of the reaction between them produces degradable bonds. For each mode, degradable bonds can be selected so that the degradable biocompatible cross-linked hydrogel polymer obtained is degraded or absorbed within the required time period range. In other embodiments, functional groups and bonds with functional groups can be selected to resist degradation under physiological conditions, thereby significantly reducing or eliminating degradation.

[0085] Typically, degradable bonds are selected that degrade into non-toxic products under physiological conditions. Degradable bonds can be chemically or enzymatically hydrolyzable or absorbable. Exemplary enzymatically hydrolyzable biodegradable bonds include peptide bonds that can be cleaved by metalloproteinases or collagenases. Additional exemplary biodegradable bonds can be functional groups on core polymers and copolymers, such as hydroxy-carboxylic acids, orthocarbonates, anhydrides, lactones, (amino acids, carbonates, phosphonates, or combinations thereof. In an exemplary embodiment, the degradable bond is an ester formed by a hydroxy-carboxylic acid moiety adjacent to an electrophilic group for cross-linking. The ester can be gradually degraded by hydrolysis under physiological conditions, with the degradation time depending on the specific structure. In order to obtain a non-degradable hydrogel, the ester formed by the hydroxy-carboxylic acid moiety can be replaced by an amide group that is not generally hydrolyzed under physiological conditions. Monomers with a PEG core are commercially available, having an N-succinimidyl electrophilic group attached with an amide bond or alternatively with an ester bond, such as from Jenkem Technology, TX, USA. PEG-amines are also available from Jenkem with various numbers of arms and molecular weights. The desired degradable electrophilic group with an ester bond includes, for example, succinic acid N-hydroxysuccinimidyl ester (SS), succinic acid N-hydroxysulfosuccinimidyl ester, glutaric acid N-hydroxysulfosuccinimidyl ester, glutaric acid succinimidyl ester (SG), adipic acid succinimidyl ester (SAP), azelaic acid succinimidyl ester (SAZ) or a mixture thereof. There is usually a correlation between the hydrolysis time and the length of the ester-forming group that is attached to the PEG core. Therefore, when in an environment that allows hydrolysis (e.g., in vivo), SS degrades more rapidly (other parameters are the same). Cross-linking density, monomer size and other parameters can additionally affect the degradation time in vivo.

[0086] Hydrogel properties

[0087] Although not desirable for all applications, the single solution hydrogel described herein can be used for a range of applications. Suitable properties generally depend on the specific application. As described in detail above, it should be noted that the required degradation time range can range from a short time (such as about one day or less) to a few days to several months of intermediate time, and in further embodiments, wherein the hydrogel is non-degradable or degrades over a long period of many years. The flexibility of chemistry and the experience of similar two-component hydrogels allow similar designs of the modulus, density, swelling and other properties of the hydrogel to be made over a considerable range. The measurement of modulus and swelling is described in Bassett et al., entitled "Hydrogels Formed In Situ and Composition Design for Intrauterine Use (hydrogels formed in situ and composition design for intrauterine use)" in the pending U.S. patent application 17 / 522,727, which is incorporated herein by reference.

[0088] Visualization reagents

[0089] In the case of convenience, biocompatible cross-linked hydrogel polymers can contain visualization agents to improve their visibility in medical procedures. As used herein, visualization agents can refer to optical visualization (with color), or visualization using imaging modes (such as x-rays or ultrasound). Visualization agents are particularly useful when used in minimally invasive surgery (MIS, such as laparoscopy) procedures, one of the reasons being their improved visibility on color monitors. Sometimes it is very useful to provide color by adding colored visualization agents to a single solution system before cross-linking.

[0090] Visualization agents (optical) can be selected from any of a variety of non-toxic colored substances suitable for medical implantable medical devices, such as FD&C BLUE dyes 1, 2, 3 and 6, indocyanine green, or colored dyes commonly found in synthetic surgical sutures. In some embodiments, green or blue are desirable because these have better visibility in the presence of blood or on a pink or white tissue background. Although visualization aids are generally useful for assisting in the correct placement of medical procedures, visualization agents can also be selected for aesthetic reasons. Therefore, for tattoo applications, visualization agents can be selected to provide the desired color while forming an aesthetic design.

[0091] For dyes used as visualization agents, they are generally water soluble. Water soluble dyes can be expected to elute from the hydrogel relatively quickly. If the dye has or is modified to have an appropriate functional group, the dye can be bound to the functional group of the hydrogel precursor, which can be done before or simultaneously with cross-linking the hydrogel. Suitable functional groups include, for example, amine (-NH2), carboxylate (-COO - ), thiol (-SH), or other suitable electrophilic or nucleophilic groups. Carboxylates can react to form –NHS groups similar to the precursor compound. For single functional groups, the dye will not crosslink, but for covalent bonding, the dye is expected to persist until the hydrogel degrades and is reabsorbed by the patient. Fluorescein-NHS is commercially available as a fluorescent red / orange dye. If desired, a panel of dyes can be used for image generation to cover primary colors or alternative colors or shades.

[0092] Visualization reagent can exist with precursor solution before delivery.Selected colored material can be chemically combined with hydrogel, or can not be chemically combined with hydrogel.Extra visualization reagent can be used, such as fluorescence (for example, green or yellow fluorescence under visible light) compound (for example, fluorescein or eosin), for visible x-ray contrast agent (for example, iodinated compound), ultrasound contrast agent (for example, microbubble) or MRI contrast agent (for example, containing gadolinium compound) under x-ray imaging equipment.Biological compatibility visualization reagent FD&C BLUE#1 and fluorescein-NHS may be particularly desirable for some applications.Visualization reagent can also be suspended or dissolved in the bioactive agent in the hydrogel matrix, or for the material of encapsulating bioactive agent (if present).

[0093] As described above, visually observable visualization agents may be advantageously used in some embodiments. Light having a wavelength of about 400 to 750 nm can be observed by humans as color (RK Hobbie, Intermediate Physics for Medicine and Biology, 2 nd Ed., pp. 371-373). When the eye receives light having a dominant wavelength of 450 to 500 nm, it perceives blue, and when it receives light having a wavelength of about 500 to 570 nm, it perceives green (ibid.). Furthermore, since the eye can detect red, green, or blue, any other color can be simulated using a combination of these colors simply by causing the eye to receive the proportions of red, green, and blue that are perceived as the desired color by the human eye. As used herein, blue refers to the color perceived by the normal human eye stimulated by a wavelength of about 450 to 500 nm, and green, as used herein, refers to the color perceived by the normal human eye stimulated by a wavelength of about 500 to 570 nm.

[0094] One or more visualization agents may be present in the final electrophilic-nucleophilic precursor solution at a concentration greater than about 0.1 weight percent (wt%), and in some embodiments, at a concentration range of at least 0.001 to about 0.075 wt%, and in further embodiments, at a range of 0.0025 to 0.05 wt%, but greater concentrations may be used, up to the limit of solubility of the visualization agent, and the selected concentration may be affected by the specific visualization agent and the specific application. In some applications, it was found that these concentration ranges provide the desired color for the hydrogel while not interfering with the crosslinking time (as measured by the time for the reactive precursor species to gel). The visualization agent is generally not covalently linked to the hydrogel. It will be appreciated by those of ordinary skill in the art that additional ranges of visualization agent concentration within the above-defined ranges are contemplated and are within the scope of the present disclosure.

[0095] In some embodiments, a method is used to form a hydrogel on a tissue until the color of the hydrogel indicates that a predetermined volume of the hydrogel has been deposited on the tissue or within the space. The precursor is continuously introduced into the space until the color of the material entering the space and flowing out is considered to have reached a suitable content, as indicated by observing a visualization agent in the flowing material.

[0096] Visualization reagent can be used to help visualize the injection of hydrogel in specific cases. For example, when injected into the fornix or subconjunctiva, visualization reagent will help to distinguish hydrogel from other fluids. In addition, the color of colored hydrogel can provide information about the concentration of the precursor in the hydrogel or the degree of physiological fluid mixing into the hydrogel. Dark hydrogel can show that the concentration of the precursor is higher than the light-colored hydrogel made of the same precursor solution. Colorant can exist in the premixed amount selected for application. In some embodiments, dye is conjugated with electrophilic or nucleophilic end groups to allow for incorporation into the long-acting preparation for visualization (directly related to persistence). In some cases, dye is fluorescent, so that it is only visualized under special lighting conditions, and single system gel is then invisible under normal visual conditions.

[0097] In some embodiments, the user can apply a single system hydrogel depot with a selected visualization agent to a tissue position to directly observe the injectable depot. The user can use a visualization agent to view the hydrogel with the human eye or by detecting an imaging device (e.g., a camera) that can visually observe the visualization agent. Visually observable visualization agents are agents with colors that can be detected by the human eye. The characteristics of providing imaging to X-ray or MRI machines are not sufficient to establish the characteristics of the function of visually observable visualization agents. An alternative embodiment is such a visualization agent: it may not be usually seen by the human eye, but when used in combination with a suitable imaging device (e.g., a camera), it is detectable under different wavelengths (e.g., infrared or ultraviolet rays). The hydrogel with a visualization agent for x-ray and / or ultrasound visualization is further described in U.S. Pat. No. 8,383,161 entitled "Radioopaque Covalently Crosslinked HydrogelParticle Implants (radiopaque covalently crosslinked hydrogel particle implants)" by Campbell et al., which is incorporated herein by reference. Ultrasound visualization may be particularly desirable for fallopian tube procedures, while x-ray visualization may be particularly desirable for tumor delivery.

[0098] Therapeutic agent delivery

[0099] Cross-linked hydrogel materials can advantageously be used for local or systemic therapy with therapeutic agents (such as drugs). Bioactive agents or drug compounds that can be added and delivered from cross-linked polymers or gels include: proteins, aminodextran, carbohydrates, nucleic acids, inorganic and organic bioactive compounds, wherein specific bioactive agents include but are not limited to: enzymes, anti-infective agents, antifungal agents, anti-inflammatory agents, anti-tumor drugs (antineoplastic agents), local anesthetics, hormones, angiogenic agents, anti-angiogenic agents, growth factors, antibodies, analgesics, anesthetics, steroids, neurotransmitters, psychoactive drugs, anticancer drugs, chemotherapeutic drugs, anti-tumor drugs, glaucoma drugs, drugs that affect reproductive ability, genes, oligonucleotides, aminodextran, antibiotics, non-steroidal anti-inflammatory drugs, anti-tumor drugs, ocular hypotensive agents, neurotransmitters, psychoactive drugs, anticancer drugs, cells, cell products or combinations thereof. As used herein, therapeutic agent refers to any bioactive agent or drug. Various preparations have been developed to provide effective therapeutic agent delivery from hydrogels with selective release rates.

[0100] To prepare such a cross-linked composition, the therapeutic agent can be mixed with a cross-linkable polymer precursor before, during, or after the aqueous precursor solution is prepared. This mixture of precursor and therapeutic agent can then be injected as a single solution system for in situ polymerization at the target delivery site. The biodegradation rate of the polymer can be selected to match the elution rate of the therapeutic agent, or it can be selected based on the properties of the therapeutic agent and the hydrogel.

[0101] In some embodiments, when the cross-linkable polymer reacts to produce a cross-linked polymer network or gel, one or more therapeutic agents are present in a separate phase. This phase separation can prevent the therapeutic agent from participating in a chemical cross-linking reaction, such as a reaction between an NHS ester and an amine group. A separate phase also helps to regulate the release kinetics of the active agent from the cross-linked material or gel, wherein the "separate phase" can be an oil (oil-in-water emulsion), a biodegradable carrier, etc. The biodegradable carrier in which the active agent can be present includes: an encapsulated carrier, such as microparticles, microspheres, microbeads, micropellets, etc., wherein the active agent is encapsulated in a bioerodible or biodegradable polymer, such as the following polymers and copolymers: poly (anhydrides), poly (hydroxy acids), poly (lactones), poly (trimethylene carbonate), poly (glycolic acid), poly (lactic acid), poly (glycolic acid)-co-poly (glycolic acid), poly (orthocarbonate), poly (caprolactone), a cross-linked biodegradable hydrogel network such as a fibrin glue or a fibrin sealant, caged and entrained molecules such as cyclodextrins, molecular sieves, etc. Microspheres made from polymers and copolymers of polylactones and poly(hydroxy acids) are of particular interest as biodegradable encapsulation vehicles.

[0102] In general, therapeutic agents or encapsulated therapeutic agents can be present in a single solution system in the form of solution or suspension. Chemical reactions between nucleophiles and electrophiles occur easily to form cross-linked gels and serve as long-acting preparations for releasing active agents to the host. Such methods of therapeutic agent delivery can be used for systemic and / or local administration of therapeutic agents.

[0103] When the cross-linked composition is used for therapeutic delivery as mentioned above, the amount of cross-linkable polymer, cross-linking agent and dosage agent introduced into the host is appropriately dependent on the specific therapeutic agent and the condition to be treated. Administration for in situ gelation can be carried out by any convenient means such as syringe, cannula, trocar, catheter, etc. Once the depot is formed, the release of the therapeutic agent can then occur, resulting in local treatment of the area. In some locations, blood flow can result in systemic distribution of the therapeutic agent, or possibly whole-organ distribution of the therapeutic agent.

[0104] Certain embodiments of therapeutic delivery hydrogels are achieved by providing compositions and methods to utilize hydrogels to control the release of relatively low molecular weight therapeutic substances. According to the principles herein, the therapeutic species is first dispersed or dissolved in one or more relatively hydrophobic rate modifiers to form a mixture. The mixture can be formed into microparticles, which are then entrained in a bioabsorbable hydrogel matrix to release a water-soluble therapeutic agent in a controlled manner. Alternatively, microparticles can be formed in situ during cross-linking of the hydrogel.

[0105] In one method of forming a therapeutic agent delivery hydrogel, hydrogel microspheres are formed from polymerizable macromers or monomers by dispersion of a polymerizable phase in a second immiscible phase, wherein the polymerizable phase comprises at least one component required to initiate polymerization (resulting in crosslinking), and the immiscible bulk phase comprises another component required to initiate crosslinking as well as a phase transfer agent. Preformed microparticles containing a water-soluble therapeutic agent can be dispersed in a hydrogel precursor solution as described above.

[0106] Embodiments of compositions and methods for forming matrices and microspheres based on composite hydrogels can have entrained therapeutic compounds. In one embodiment, the bioactive agent is entrained in microparticles with hydrophobic properties (referred to herein as "hydrophobic microdomains") to delay the leakage of entrained agents. In some embodiments, the composite material has a two-phase dispersion, in which both phases are absorbable, but not miscible. For example, the continuous phase can be a hydrophilic network (such as a hydrogel, which may or may not be cross-linked), and the dispersed phase can be hydrophobic (such as oil, fat, fatty acid, wax, fluorocarbon or other synthetic or natural water-immiscible phases, collectively referred to herein as "oil" or "hydrophobic" phases).

[0107] If an oil phase is used, the oil phase entrains the drug and provides a barrier to release by slowly distributing the drug into the hydrogel. The hydrogel phase in turn protects the oil from being digested by enzymes (such as lipase) and from being dissolved by naturally occurring lipids and surfactants. The latter are expected to penetrate into the hydrogel only to a limited extent, for example, due to hydrophobicity, molecular weight, conformation, diffusion resistance, etc. In the case of hydrophobic drugs with limited solubility in the hydrogel matrix, the particle form of the drug can also be used as a release rate modifier.

[0108] When administered in vivo, the hydrophobic microdomains themselves may be degraded or rapidly cleared, making it difficult to directly utilize droplets or microparticles containing entrained agents to achieve extended release in vivo. However, according to some embodiments, the hydrophobic microdomains are isolated in a gel matrix. The gel matrix protects the hydrophobic microdomains from rapid clearance, but does not impair the ability of the droplets or microparticles to slowly release their contents. Visualization agents can be included, for example, in the gel matrix or microdomains.

[0109] In other aspects of the composition, the active agent is hydrophobic and poorly water-soluble, and is itself a hydrophobic domain. Insoluble drug particles can actually be micronized to allow uniform suspension throughout the hydrogel as a whole and allow consistent application without clogging the delivery system. After the in-situ system is formed, hydrophobic poorly soluble drug particles are still confined in the gel matrix, thereby forming a concentrated environment that acts as a diffusion barrier for further drug dissolution, because the drug needs to be dissolved and then diffused out of the matrix to release. Poorly soluble hydrophobic drugs may experience zero-order or first-order release kinetics, depending on their solubility, the amount loaded into the gel, and the surface area of ​​the applied hydrogel. In more confined environments, such as the eye or subcutaneous, because the local tissue is saturated with the drug, the release kinetics may be further extended, thereby further limiting the diffusion path from the hydrogel.

[0110] In another aspect of the composition, the hydrogel microspheres are formed to a size that will provide for selective deposition of the microspheres, or the hydrogel microspheres can be linked to ligands that target specific areas or otherwise affect deposition of the microspheres within a patient.

[0111] By degradably covalently linking bioactive molecules to a cross-linked hydrogel network, controlled drug delivery rates can also be achieved using the system of the present invention. The properties of the covalent link can be controlled to enable control of release rates from hours to weeks or longer. By utilizing composite materials made from bonds with a range of hydrolysis times, controlled release profiles can be extended to longer durations.

[0112] In certain embodiments, the addition of the therapeutic agent does not raise the existing pH of the unbuffered system so that the acid conjugate is not overwhelmed. In other embodiments, the therapeutic agent is encapsulated or phase separated. The choice of therapeutic agent is often influenced by the specific application. In this case, some specific drugs / therapeutics are mentioned in the discussion of specific applications below.

[0113] Blocked fallopian tubes

[0114] The hydrogel can provide desired functionality with respect to blocking the fallopian tubes as a means of birth control or other medical reasons. The single solution hydrogel system described herein is particularly convenient because it eliminates significant time constraints on delivering the hydrogel to both fallopian tubes. Relative to the two-component hydrogel system, the hydrogel can effectively conform to the irregular surface of the fallopian tube, and the confined space can be consistent with a fast but slightly slower gelation time. A specific applicator is described, but other devices can be used if desired.

[0115] Figure 3A and 3BA delivery system applicator suitable for delivering a single solution as described herein to occlude a body cavity such as a fallopian tube is shown. The delivery system 300 includes a multi-lumen catheter 302 having a proximal end 304 and a distal end 306. The proximal end 304 includes an inlet port 322, which is coupled to outlet ports 312, 314, 330 disposed near the tip 316 via a lumen 326. The balloon inflation port 324 is coupled to a balloon 332 via a balloon lumen 328. The two lumens 326, 328 may be located at a distal end 306. Figure 3B 326 is seen in the cross-sectional view of . In this embodiment, lumen 326 plays the two roles of guidewire lumen and lumen for delivering hydrogel. With guidewire 334 in place, outlet port 330 is substantially blocked and cannot allow hydrogel precursor solution to flow out. Alternatively, in operation, lumen 326 can initially be used to position delivery system 300 at a desired location, and then guidewire 334 is withdrawn. A single solution is then injected through inlet port 322 and enters lumen 326, and finally flows out through outlet port 330, and outlet ports 312, 314 can still be used or removed.

[0116] The radiopaque marker band 333 is arranged in the balloon 332 or other positions on the distal end 306 to help position the distal end 306 of the delivery system 300 in the body cavity under fluoroscopic guidance. The guide wire 334 extends through the inlet port 322 and the outlet port 330, and can be used to guide the tip 316 of the delivery system 300 to the treatment site, such as the fallopian tube, peripheral blood vessels, aneurysms or other body cavities, for example, in the cavity. During the formation of the hydrogel implant, the balloon 332 can be expanded to anchor the catheter 302 in the position in the body cavity, and the lumen can also be blocked to prevent fluid flow so as not to dilute the single solution system during gelation. The delivery system 300 can optionally include an outer sheath surrounding the balloon when the balloon 332 is deflated (deflated).

[0117] Alternatively, catheter 302 can be configured to have three lumens, for example, a hydrogel precursor lumen, a guidewire lumen, and a balloon lumen, thereby providing separate guidewire and hydrogel precursor lumens such that outlet port 330 is not coupled to outlet ports 312 and 314. In this case, the hydrogel precursor lumen couples the hydrogel precursor inlet port to outlet ports 312 and 314, the guidewire lumen couples inlet port 322 to outlet port 330, and the balloon lumen 328 couples balloon inflation port 324 to the interior of balloon 332. In operation, the guidewire lumen is used to position the delivery system 300 at a desired location, and then a single solution is injected through the hydrogel precursor inlet port. The solution cross-links after placement into the body cavity. As Figure 3A and 3BIn a further alternative embodiment of the present invention, the guidewire lumen need not extend the length of the catheter to form a so-called "over the wire" catheter. Instead, the guidewire lumen can be configured as a shorter lumen that exits the catheter 302 through an incision only at the proximal end of the balloon 332 to form a so-called "rapid exchange" catheter, as described, for example, in Bonzel's U.S. Pat. No. 4,762,129.

[0118] refer to Figure 4 , describes a method using Figure 3A A method of delivering a single solution system into the lumen of a fallopian tube to form a hydrophilic hydrogel occlusion is provided using a delivery system 300. The fallopian tube F1 is entered by passing a catheter 302 through the cervix C under fluoroscopic guidance. The proximal end 304 of the delivery system 300 is coupled to a single syringe-type device 340 that contains a single solution system 341 and has an actuator 342 that allows for controlled injection of the single solution system 341. The balloon 332 can be inflated with a fluid containing a contrast agent to verify the placement of the tip 316.

[0119] If desired, after inflating balloon 332, the treatment space can be filled or flushed with a solution (e.g., an inert saline solution) to remove blood and other physiological fluids from the treatment space. Delivery system 300 optionally can include additional lumens or use existing lumens (e.g., lumen 326) to allow such flushing fluid to exit the treatment space. Alternatively, a non-inert solution (e.g., a solution containing a pharmaceutical agent) can be injected into the treatment space.

[0120] The actuator 342 is then pressed so that the single solution system 341 is delivered into the fallopian tube through one or more outlet ports at the distal end of the balloon 332. There are no particular limitations on the delivery rate and total delivery time of the single solution system 341. In some embodiments, the delivery time is about 30 seconds, about 1 minute, about 5 minutes, or about 10 minutes. In some embodiments, the initial delivery of the single solution system 341 can be performed with a pause of a few seconds or minutes. The single solution cross-links about 30 seconds to about 5 minutes after contact with the fallopian tube tissue, thereby forming an embolism 344 that blocks the fallopian tube F1. The balloon 332 is then deflated and the catheter 302 is partially withdrawn. The delivery system 300 is continued to be used, and then the fallopian tube F2 is entered under fluoroscopic guidance, and the above procedure is repeated to form an embolism 346.

[0121] In some embodiments, the method of tubal occlusion can be controllably reversible by using a single solution system 341 that forms plugs 344 and 346 that are degradable after a selected period of time. The selection of nucleophilic and electrophilic functional groups can be used to adjust the degradation time of the hydrogel plug. In other embodiments, the method of tubal occlusion can be made permanent by using nucleophilic and electrophilic functional groups that react to form bonds that resist hydrolytic degradation (such as amide bonds). Tubal patency checks can be performed immediately after insertion of the plugs 344 and 346, periodically, and / or after a selected reversal period of time to test the effectiveness of the plugs 344 and 346 in occluding the fallopian tubes F1 and F2.

[0122] For these applications, the hydrogel can be loaded with some selected drug. Suitable drugs can include, for example, anti-infective agents or anti-fungal agents for treating uterine infections, where the effectiveness is improved due to the local target proximity of the agent. For example, the following antimicrobial agents may be suitable: antiviral agents, broad-spectrum antibiotics (such as penicillins and cephalosporins), metronidazole (for bacterial vaginosis and trichomoniasis), fluconazole (antifungal agent - for yeast infections), doxycycline or azithromycin. Anti-infective agents may need to be deployed prophylactically in some cases. Anti-inflammatory agents (such as NSAIDs or steroids) are another class of agents that can be used to treat conditions such as endometriosis without the systemic side effects associated with long-term use of these agents.

[0123] Agents such as hormones benefit from local intrauterine delivery, ranging from the treatment of endometriosis or as hormone replacement therapy (HRT) in postmenopausal women. Oral contraceptive use is associated with an increased risk of thromboembolism as well as breast cancer incidence. The more mild side effects of oral contraceptive use, such as mood changes, weight gain, intermenstrual vaginal bleeding and spotting, and loss of libido, may lead to inconsistent oral dosing or discontinuation, translating into failure rates of up to 5% during the first year of oral contraceptive use. At the other end of the life cycle, oral administration of HRT in postmenopausal women is associated with an increased risk of coronary heart disease, stroke, and venous thromboembolism, as well as an increased risk of breast cancer the longer treatment is continued.

[0124] Antitumor drug delivery

[0125] The hydrogel systems described herein provide an important tool in the context of drug delivery to treat tumors. The use of a single solution system described herein provides the advantage of allowing effective injection into a tumor at multiple locations without clogging the applicator. Thus, a more uniform delivery of anti-tumor agents can be achieved. As will be appreciated by those of ordinary skill in the art, the tumor can be approached using appropriate medical techniques for the specific tumor location.

[0126] A specific drug can be selected based on the specific tumor type, and typically the drug will be approved by the relevant medical regulatory agency. Hydrogel delivery methods can be effective for delivering drugs that, for example, due to toxicity or solubility limitations, may not have an effective delivery method using non-targeted methods (e.g., systemic delivery methods). Therefore, cytotoxins can be delivered using these hydrogel systems, and the drug elution rate can be designed accordingly.

[0127] The article by Yi et al. cited above discusses the hydrogel delivery of the anticancer drug 5-fluorouracil, and this drug can be similarly delivered with a single solution, in situ hydrogel described herein. 5-Fluorouracil is commonly used to treat colorectal cancer, esophageal cancer, gastric cancer, pancreatic cancer, breast cancer, cervical cancer, actinic keratosis, and basal cell carcinoma. Other categories of anticancer agents include, for example, monoclonal antibodies and cytokines. A review of the potential for using hydrogels to deliver anticancer agents can be found in Zhang et al. "Locally Injectable Hydrogels for Tumor Immunotherapy," Gels, 2021, 7, 224, which is incorporated herein by reference.

[0128] Select further implementation

[0129] In some embodiments, the hydrogel may include a polymer comprising the group -(CH2CH2O)-. The hydrogel may also include a therapeutic agent. In some embodiments, the hydrogel may be degradable in vivo. For example, the hydrogel may be hydrolytically degradable. The hydrogel may be degradable in vivo in less than 5 days, less than 8 days, less than 15 days, while in other embodiments, the hydrogel may not degrade in vivo. The hydrogel may be degradable in vivo in more than about half a day and in less than about 770 days. Generally, the degradation time may be appropriately selected for a particular application. It will be appreciated by those of ordinary skill in the art that additional ranges of degradation times within the above ranges are contemplated and are within the scope of the present disclosure.

[0130] The method of applying the hydrogel may include applying a single solution system comprising two reactive precursors (capable of forming a hydrogel in the absence of an external or auxiliary activator). The method may include applying two or more reactive precursor components in an aqueous system to form an in situ gel in the absence of an external activator (such as radiation, pH accelerator, redox reaction or thermal activation). The hydrogel precursor solution can be applied through an intraluminal channel (including a catheter, a needle, a port) using a standard fluid application method associated with a single system injection (without mixing). The method of application may incorporate a visualization agent. In some embodiments, the agent is a water-soluble biocompatible dye such as FD&C Blue#1 to provide a contrast with relative tissue and / or blood. In other embodiments, the dye may be conjugated with an electrophilic or nucleophilic group and premixed with a reactive precursor in the same aqueous solution. In a specific embodiment, the dye is a fluorescein-NHS conjugate, which can be attached to the hydrogel network and allow the gel to be observed via fluorescence through the tissue.

[0131] A single solution system containing two reactive precursors capable of forming a gel can be used without an external or auxiliary activator required to form a long-acting preparation in vivo. A single solution system is used in clinical applications, where the flow of one or more precursor solutions may be limited, or the area of ​​diffusion is limited, as defined by surrounding tissue / organ / anatomical features, where the need for rapid gelation is not critical. In more specific applications, the gel time may range from 10s to 10min, 15s to 5min in further embodiments, and 20s to 2 minutes in other embodiments. A desirable feature of the hydrogel system described herein is that, for the delivery of the system, no unique or customized delivery system is required, and it can be repeatedly started and stopped during use, although specific applicators may be desired for some applications. Applications may have, for example, a delivery location suitable for crosslinking after entering the body, without the need to add an auxiliary activation source such as radiation. Some specific applications include, for example, tattoos or high-pressure needle-free injections, where even a small crosslinking initiated before passing through the dermis can lead to significantly reduced penetration efficacy and / or blockage. Other applications involve nasal locations, where more than one injection may be required through more than one orifice present.

[0132] In some applications, the delivered long-acting formulation can be used as a volume-enlarging agent for tissue enlargement. Enlargement can include dermal filling or intracavitary volume-enlargement, such as enlarging hollow blood vessels or organ walls to prevent the stenosis of intracavitary cavities. Volume-enlarging applications can include sphincter enlargement throughout the body, or cervical volume-enlargement to prevent premature birth. On the contrary, a single solution system is used to enlarge and further open hollow blood vessels in the presence of an expanded conventional balloon catheter. This can include enlarging the urethra in the presence of a swollen prostate to reduce conventional catheterization for bladder relief. Enlargement can also have aesthetic applications, such as about smoothing or wrinkles, etc. Enlargement can be carried out with a shorter residence or a longer residence (such as non-degradable hydrogel). Other aesthetic applications include tattoo applications. Traditional tattoos are essentially permanent, and their removal may require painful processing. It is described above that a tattoo is formed using a dye, and the combination of a dye and a hydrogel can provide for the dye to persist in the duration of the hydrogel, and remove the dye as the hydrogel decomposes. Temporary tattoos are usually short-lasting and have an appearance different from traditional tattoos. Hydrogel-based tattoos can be relatively durable, offer the potential for similar appearance, and are medically safe. The composition can be delivered using a medical needle or a standard tattoo apparatus, see published U.S. patent application 2021 / 0386988, entitled “Tattoo Needle Unit” by Kim et al., and U.S. patent application 2021 / 0386987, entitled “Robotic Tattooing Systems and Related Technologies” by Azdoud et al., both of which are incorporated herein by reference.

[0133] In some embodiments, any or all of the clinical applications may be suitable, where an active therapeutic agent may be added to provide local treatment. In some embodiments, the addition of a therapeutic agent has a complementary effect on the action of the device, such as adding an anesthetic to an incremental injection for alleviating pain from an injection event. In other cases, a more traditional therapeutic agent may be required. Applications using a single precursor solution are different from embodiments using a dual solution precursor system because no specialized equipment is required and reduced manual dexterity may be involved. Other desired applications may involve uses where skill is required to adjust the volume and stop-start applicability is required. One such application is the administration of a long-acting formulation of a therapeutic agent into the ear through the tympanic membrane, where injection without concern for clogging more effectively prevents unwanted side effects of an injection event.

[0134] In certain embodiments, application is purely to form a long-acting preparation for therapeutic release, such as direct injection into a tumor containing a therapeutic agent for chemotherapy delivery, where conventional entry (including intravascular) is impossible. Other embodiments include delivery of chemotherapeutic agents for the treatment of cancers where 4-6 months of treatment are required. Therapeutic agent delivery can be achieved by high-loaded low-solubility compounds, secondary encapsulation, or methods known in the art. Therapeutic agent delivery can also be achieved by incorporating a secondary hydrogel particle system (suspended in a primary system) containing a therapeutic agent.

[0135] Other therapeutic clinical embodiments involve the formation of ocular surface depots, such as fornix-based depots for therapeutic delivery, including for the treatment of infection, allergy, inflammation, and glaucoma. Additional embodiments include intraocular injections for sustained release into the anterior and / or posterior chambers of the eye, with targeted delivery of anti-inflammatory agents, anti-infective agents, biologics, prostaglandins, beta blockers, etc. for treatment.

[0136] Other suitable applications can involve minute repeat administrations requiring a single system depot, where off-target applications can result in undesirable side effects. An example of such application is to tattoo the eyelid margin with a single system, using a continuous depot of prostaglandins to enhance eyelash thickness without causing the eye region or potential iris to become brown off-target. Latisse (Allegan) is a product containing the prostaglandin bimatoprost approved by the FDA that can be applied along the eyelid margin to thicken and additionally enhance eyelashes. The dual hydrogel precursor system will require external coloring of the eyelid similar to Latisse to achieve surface area coverage without clogging, thereby making the application of hydrogel depots easy to dry and brittle. Other injections include prostaglandins below the eye for continuous ablation of fat and reduction of "eye bags", where a single system with an acid conjugate and no activator can be diffused by multiple injections, and dual systems known in the art can result in undesirable single large dose injections. XAF5 (developed by Topokine Therapeutics) is a topical eye ointment containing prostaglandins that is used to reduce eye bags and is in clinical trials. Example

[0137] Example 1: In vitro performance studies

[0138] This example demonstrates the performance of a one-component system via an in vitro model of a reservoir of physiological fluids.

[0139] The one-component system was prepared by combining the first and second precursors (both as dry powders), unbuffered water for injection (WFI, pH 5.5) and a trace amount of FD&C Blue #1 (less than about 0.011% w / w) to form a solution with a precursor concentration of 10% w / w. The solution was blue. The first precursor was an eight-arm polyethylene glycol-based precursor (8A15k PEG SG, Jenkem USA) with a molecular weight of 15,000 Da and succinimidyl glutarate (SG) functional end groups. The second hydrogel precursor was an eight-arm polyethylene glycol-based precursor (8A20k PEG amine-HCl, Jenkem USA) with a molecular weight of 20,000 Da and HCl-salified amine functional end groups. The first and second precursors were used in a weight ratio of 3:4 to provide approximately equal amounts of SG and amine functional end groups in the solution. These precursors dissolved rapidly in WFI, as determined by the absence of particulate matter by visual inspection. After dissolving, the prepared solution was immediately sucked into a 5ml syringe and a 27G gauge needle was fixed. Over a 30-minute period, 200 μl of room temperature solution was temporarily injected into a 200 μl aliquot of phosphate buffered saline (PBS) at 37°C through a 27G gauge needle. The solution remained flowable and injectable through a ** gauge needle throughout the 30-minute working window observation time. Each injection resulted in a blue solid to semi-solid mass formed in the PBS solution due to gel formation caused by the cross-linking of the precursor. This study shows that the one-component system has a stability of more than 30 minutes after preparation.

[0140] Example 2: In vitro performance study (with comparative examples)

[0141] This example demonstrates the time-dependent performance of the one-component system of Example 1 and a one-component system with trilysine as the second hydrogel precursor. A single solution composition similar to the system of Example 1 except that the amine functional end groups of the second precursor were not HCl-salified was compared.

[0142] According to Table 1, two one-component systems ("Study System 1" and "Study System 2") and a comparative system (CS-1) were prepared from a first precursor, a second precursor, and unbuffered water for injection (WFI). CS-1 was prepared from the same precursors as Study System 1, except that the second precursor in CS-1 was not salified with HCl. The precursors in dry powder form were combined with WFI and a trace amount of FD&C Blue #1 (less than about 0.011% w / w) to form a solution having a precursor concentration of about 10% w / w. The first and second precursors were used in a weight ratio to provide approximately equal amounts of SG and amine functional end groups in each solution. The initial pH of Study System 1 was 2.91, and the initial pH of Study System 2 was 5.21. The precursors in these study systems dissolved rapidly in WFI, as determined by the absence of particulate matter by visual inspection. Rapid gelation occurred after forming solution CS-1. The pH of the comparative system could not be measured before gelation.

[0143] Table 1

[0144]

[0145] *The pH of the system cannot be measured before gelation

[0146] After dissolution, 150 μl aliquots of research system 1 were delivered to 50 μl aliquots of phosphate buffered saline (PBS) at 37°C using a pipette immediately. This process was repeated twice additionally for a total of three samples. Visual evaluation of gelation was performed based on the sticky bullae formed around the rotating micro-stirring rod. The time of gelation at 0 minute after dissolution was recorded for each sample, as shown in Table 2. The average gel time was 23.11 seconds. At 30 minutes, 60 minutes and 90 minutes after dissolution, the process was repeated. Similarly, after dissolution, 150 μl aliquots of research system 2 were delivered to 50 μl aliquots of phosphate buffered saline (PBS) at 37°C using a pipette immediately. The process was repeated for the second sample. As shown in Table 2, the time of gelation was 101.75 seconds (for sample 1) and 101.44 seconds (for sample 2). The average gel time of Research System 2 at 0 minutes after dissolution was 101.60 seconds (about 1.7 minutes), which is significantly longer than the average gel time of 23.11 seconds for Research System 1. The first sample of Research System 2 was tested 30 minutes after preparation, however, the gel time result was questionable due to the presence of gel in the solution during pipetting. The second 150 μl aliquot of Research System 2 could not be pipetted due to the presence of gel. Accordingly, samples could not be taken at 60 and 90 minutes, as shown in Table 2. The 150 μl aliquot of CS-1 could not be pipetted due to the presence of gel.

[0147] Table 2

[0148]

[0149] 1 The presence of the gel did not allow pipetting of the sample.

[0150] 2 The gel was present during the aspiration of the sample.

[0151] Comparison of Study System 1 with CS-1 showed that replacing the non-salted form of the second precursor resulted in gel formation immediately after preparation. CS-1 did not exhibit storage stability. Comparison of Study System 1 with Study System 2 showed that replacing the second precursor with trilysine resulted in less than 30 minutes of storage stability and a significantly increased gel time when tested immediately after dissolution. This study showed that only Study System 1 had a storage stability of more than 30 minutes after preparation. In addition, Study System 1 had a gel time of less than 30 seconds. This study further showed that Study System 1 had a storage stability of more than 90 minutes, and throughout this storage period, the gel time did not exceed 50 seconds.

[0152] Example 3: In vitro performance study of the system with buffer

[0153] This example demonstrates the effect of buffer on the performance of a one-component system.

[0154] A one-component system (Investigational System 1B) was prepared from the first and second precursors of Investigational System 1 of Example 2. For Investigational System 1B, the precursors were dissolved in a 0.01 M sodium dihydrogen phosphate buffer solution, pH 4.01 (rather than WFI), as shown in Table 3. The precursors in dry powder form were combined with the buffer solution and a trace amount of FD&C Blue #1 (less than about 0.011% w / w) to form a solution with a precursor concentration of about 10% w / w. The first and second precursors were used in a weight ratio to provide approximately equal amounts of SG and amine functional end groups in each solution. The initial pH of Investigational System 1 was 2.91, and the initial pH of Investigational System 1B was 2.09. For each solution, the precursors dissolved rapidly, as determined by the absence of particulate matter upon visual inspection.

[0155] Table 3

[0156]

[0157] After dissolving, 150 μ l aliquots of research system 1B were delivered to 50 μ l aliquots of phosphate buffered saline (PBS) at 37 ℃ using a pipette immediately. This process was repeated twice additionally for a total of three samples. The time of gelation after dissolving for each sample was recorded at 0 minute, as shown in Table 4. The average gel time was 48.14 seconds. This gel time is more than twice the gel time of research system 1. The result directly shows the effect of using a buffer solution relative to (unbuffered) WFI as a solvent for the precursor. After research system 1B dissolved for 30 minutes, 60 minutes and 90 minutes, the procedure was repeated. For each time period tested, research system 1B showed an increase of at least 45% in the average gel time.

[0158] Table 4

[0159]

[0160] This study showed that the investigational system 1B had a storage stability of more than 90 minutes after preparation and throughout this storage period the average gel time did not exceed 70 seconds. The results indicate that buffers can be used with the systems described in this invention, but the addition of buffers does not appear to provide superior or even equivalent results to systems prepared with WFI.

[0161] Example 4: Effect of buffer concentration on in vitro performance

[0162] This example demonstrates the effect of buffer concentration and system pH on the performance of a one-component system.

[0163] A one-component system (Investigational System 1C) was prepared from the first and second precursors of Investigational System 1 of Example 2. For Investigational System 1C, the precursors were dissolved in a 0.01 M sodium dihydrogen phosphate buffer solution at pH 4.01 as shown in Table 5. The precursors in dry powder form were combined with the buffer solution and a trace amount of FD&C Blue #1 (less than about 0.011% w / w) to form a solution having a precursor concentration of about 10% w / w. The first and second precursors were used in a weight ratio to provide approximately equal amounts of SG and amine functional end groups in each solution. The precursors dissolved rapidly, as determined by the absence of particulates upon visual inspection. The initial pH of Investigational System-C was 2.92.

[0164] Table 5

[0165]

[0166] Immediately after dissolution, a 150 μl aliquot of Study System 1C was delivered using a pipette into a 50 μl aliquot of phosphate buffered saline (PBS) at 37°C. The process was repeated for the second sample. The pH of Study System 1C and the time for gelation to occur for each sample after dissolution were recorded, as shown in Table 6. A 250 μL aliquot of concentrated dihydrogen phosphate (0.0121 g dihydrogen salt / mL; pH 4.30) was added to the vial containing Study System 1C. The pH was measured. The gel time of the resulting solution was measured as described above. Additional aliquots of the concentrated dihydrogen salt solution were added, as shown in Table 6. The pH and gel time were measured after each addition. The results shown in Table 6 are plotted as a function of the gel time (left axis) and the amount of concentrated dihydrogen salt added ("dilution amount", right axis) as a function of the system pH. Figure 5 middle.

[0167] Table 6

[0168]

[0169] Figure 5 It is shown that the gel time increases nonlinearly with pH. When the initial pH is 2.92, the average gel time is about 51.88 seconds. When the pH is 3.16, the average gel time has more than doubled to 114.97 seconds. When the pH is 3.35, the average gel time is 269.16 seconds (about 4.5 minutes), which is more than 5 times the gel time of the solution of the studied system 1C. These results show that when the solution approaches the pH buffer range of the buffer, the gel time is more affected by the presence of the buffer as the pH changes. Obviously, the single solution system of this embodiment does not show storage stability limitations within the pH range studied.

[0170] This study shows that a range of buffer concentrations and pH can be used with the precursors described in this invention, but that the addition of buffer (and the associated change in pH) has the effect of increasing gel time, especially when approaching the pH range of the buffer. These results are good evidence of the role of buffering, since gelation involves raising the pH to deprotonate the amines, but the buffered system (with an initially higher pH) gels significantly more slowly.

[0171] Example 5: Subcutaneous Performance Study

[0172] This example evaluates the effect of precursor concentration on the performance of a one-component system via an in vivo model. The efficacy of the one-component system for repeated subcutaneous injections across a tissue was also evaluated.

[0173] The three concentrations of the one-component system described in Example 1 were prepared to form 10% w / w solutions, 20% w / w solutions, and 30% w / w solutions. For each solution, the precursor dissolved rapidly in WFI, which was determined by visual inspection. After dissolution, each prepared solution was immediately drawn into a separate 5 ml syringe and a separate 25-gauge needle was fixed. Approximately 500 μl of each of the three solutions was injected subcutaneously into different but similar locations along the pig's abdomen in a sedated pig (weight 65 kg). It was observed that the 10% and 20% solutions formed obvious gel pockets, which could be felt as hard subcutaneous masses about 10-30 seconds after injection. Each injection site was dissected 1 minute after injection. The injection sites of the 10% and 20% solutions showed the presence of blue gel. After dissection, the injection site of the 30% solution revealed blue liquid oozing from the subcutaneous placement site, indicating that gel had not yet formed. It was observed that the 30% solution gelled in the dissected placement site after a 2-minute time period. These results indicate an upper concentration limit for achieving gel formation using a one-component system.

[0174] According to preliminary studies, the original 10% solution (using the original syringe and needle) was used to perform a series of closely spaced subcutaneous injections in the porcine urethra. Each injection delivered a volume of approximately 250 μl. The injections were performed for 5 minutes, during which no evidence of needle clogging was observed. The presence of the gel at the injection site after 10-30 seconds was confirmed by pressing / squeezing the tissue. A series of beads of hard subcutaneous masses could be felt, indicating that repeated injections formed an interconnected gel.

[0175] This study demonstrated that the one-component system is concentration-dependent and can be effectively used with small-gauge needles for repeated subcutaneous injections, forming a gel within 10–30 seconds.

[0176] Example 6: Multi-site performance study

[0177] This example evaluates a one-component system for sequential use at multiple locations in an in vivo model.

[0178] A 10% w / w solution was prepared according to Example 1, with the modification that a small amount (less than 0.001%) of fluorescein-NHS was added to the solution. Immediately after dissolution, the prepared solution was drawn into a 5 ml syringe and a 30 gauge needle was attached.

[0179] Part A: Subcutaneous Injection Site

[0180] Approximately 500 μl of the solution was injected subcutaneously into the subcutaneous tissue of a pig (65 kg body weight) that had just been euthanized. In less than 10 seconds, the gel was felt to be hard and intact under the dermis. One minute after injection, the injection site was dissected and evaluated under blue light. The presence of the gel formed a raised mass on the surface of the outer epidermis. The gel can be seen through the outer epidermis, showing that the gel was slightly oval and flattened in the shape of a sphere with a radius of about 15 mm. The presence of the gel and its size and shape were confirmed by dissection.

[0181] Part B: Subconjunctival injection site

[0182] Using the same solution, syringe and needle as for Part A, approximately 200 μl of the solution was injected subconjunctivally into one eye of the pig from Part A. After injection, the injection site was visualized under blue light. In less than 10 seconds, the gel was felt to become firm and intact under the dermis.

[0183] Section C: Periodontal Injection Sites

[0184] Using the same solution, syringe and needle as for parts A and B, approximately 250 μl of the solution was injected multiple times under the gums of the pigs from parts A and B. After injection, the injection site was visible under blue light, which showed the presence of multiple small gel depots. In less than 10 seconds, the gel was felt to become firm and intact under the dermis.

[0185] This study shows that a single solution, syringe and needle can be used to deliver hydrogel depots to multiple locations in the body over a period of about an hour. During this period, the time for gelation to occur remains at about 10-30 seconds. The study also shows that contrast agents can be used to observe the size and location of hydrogels through the dermis of various tissues.

[0186] Example 7: Multi-site ocular performance study

[0187] This example evaluates a one-component system for sequential use at multiple ocular locations in an in vivo model.

[0188] A 10% w / w solution was prepared according to Example 6. Immediately after dissolution, the prepared solution was drawn into a 5 ml syringe and affixed with a 30 gauge needle.

[0189] Part A: Eyelid Injection Site

[0190] A separate 50 μl aliquot of the solution was injected into each of five locations on the eyelid margin of a freshly euthanized pig (weight 65 kg). The injection site was visualized under blue light and with a yellow filter, which revealed the presence of multiple small gel depots on the eyelid. The gel became firm and felt intact under the dermis in less than 10 seconds.

[0191] Part B: Intracameral injection site

[0192] Using the same solution, syringe, and needle as in Part A, approximately 100 μl of the solution was injected into the anterior chamber of the pig's eye from Part A. The injection site was visualized under blue light with a yellow filter. Since the fluorescein-NHS dye does not dissipate or migrate through the aqueous humor, the gel was determined to be solid after 10 seconds.

[0193] This study demonstrated that a single solution, syringe, and needle can be used to deliver a hydrogel depot via a small gauge needle to multiple ocular locations, including repeated injections along the eyelash line and injections into the anterior chamber without clogging the needle. In this study, injections were successfully performed using the solution over a period of approximately 1 hour, and during this period, the time for gelation to occur remained at approximately 10-30 seconds.

[0194] Example 8: Multiple-site skin injection study

[0195] This example evaluates a one-component system for sequential use at multiple skin locations in an in vivo model.

[0196] A 10% w / w solution was prepared according to Example 6. Immediately after dissolution, the prepared solution was drawn into a 5 ml container of a commercial tattoo device (ie, gun).

[0197] Part A: Subcutaneous injection

[0198] A continuous line of solution was injected into the inner abdomen of a freshly euthanized pig (weight 65 kg). The injection site was visible under blue light and using a yellow filter, which showed the presence of a continuous line of gel depot on the pig's abdominal skin. The gel was distinct and non-migrating and could be seen under fluorescent light.

[0199] Other inventive concepts

[0200] 1. A method for injecting an in situ cross-linked hydrogel into a patient's fallopian tube, the method comprising:

[0201] The hydrogel precursor solution is delivered directly into a first fallopian tube of the patient and subsequently into a second fallopian tube of the patient using an applicator, wherein the applicator includes a reservoir of the hydrogel precursor solution connected to a catheter configured to place the hydrogel precursor transcervically within the fallopian tube, and wherein the hydrogel precursor solution includes a mixture of a first compound having a plurality of electrophilic groups, a second compound having a plurality of nucleophilic groups, and an aqueous solvent having a pH of no greater than about 6, wherein the hydrogel precursor solution gels in no more than about 3 minutes upon contact with tissue of the first fallopian tube and gels in no more than about 3 minutes upon contact with tissue of the second fallopian tube.

[0202] 2. The method according to inventive concept 1, wherein the delivery is guided by x-ray, ultrasound or other medical imaging.

[0203] 3. The method according to inventive concept 1 or 2, wherein the catheter configured for transcervical placement comprises a balloon, wherein the balloon can be inflated after the catheter is placed in the opening of the fallopian tube and before the hydrogel precursor solution is delivered.

[0204] 4. The method according to any one of inventive concepts 1 to 3, wherein the first compound comprises a multi-arm polyethylene glycol having a succinimidyl functional group, and the second compound comprises a multi-arm polyethylene glycol having a protonated amine functional group.

[0205] 5. The method according to any one of inventive concepts 1-4, wherein the hydrogel precursor solution gels to form a first occlusion in a first fallopian tube and a second occlusion in a second fallopian tube.

[0206] 6. The method according to inventive concept 5, wherein the first occlusion and the second occlusion provide reversible or permanent female sterilization.

[0207] 7. The method according to any one of inventive concepts 1 to 6, further comprising performing a fallopian tube patency test after a selected period of time.

[0208] 8. A method for delivering an in situ cross-linked medical hydrogel, the method comprising:

[0209] blending the electrophilic precursor and the nucleophilic precursor with an aqueous solvent having a pH not exceeding about 6 to form a precursor solution having a storage stability against mobility limitations of at least about 10 minutes at room temperature, the storage stability being determined by the precursor solution being injectable from a 5 ml syringe with a 25 gauge needle; and

[0210] An amount of the precursor solution is delivered to a patient, wherein the precursor solution contacts physiological fluids associated with vital physiological tissue to induce cross-linking of the hydrogel, wherein the hydrogel gels in vivo in no more than about 5 minutes.

[0211] 9. The method according to inventive concept 8, wherein the electrophilic precursor and the nucleophilic precursor are powders.

[0212] 10. The method of claim 8 or 9, wherein the electrophilic precursor comprises a first hydrophilic polymer core and a plurality of electrophilic functional groups, wherein the nucleophilic precursor comprises a second hydrophilic polymer core and a plurality of protonated amine groups, and wherein the electrophilic precursor and the nucleophilic precursor are water soluble.

[0213] 11. The method according to any one of inventive concepts 8-10, wherein the electrophilic precursor and the nucleophilic precursor independently have a molecular weight of about 2K Da to about 50K Da and 4 to 8 arms.

[0214] 12. The method according to inventive concept 11, wherein the plurality of electrophilic functional groups comprise reactive esters.

[0215] 13. The method according to inventive concept 11, wherein the first hydrophilic polymer core and / or the second hydrophilic polymer core comprises polyethylene glycol, polyvinyl alcohol, polylactic acid, polyoxazoline, copolymers thereof or mixtures thereof.

[0216] 14. The method according to any one of inventive concepts 8 to 13, further comprising an additional electrophilic precursor and / or an additional nucleophilic precursor.

[0217] 15. The method according to any one of inventive concepts 8-14, wherein the precursor solution further comprises a therapeutic agent and / or a visualization agent, the visualization agent comprising a colorant, a fluorescent molecule, an ultrasound contrast agent, an x-ray contrast agent, an MRI contrast agent, or a combination thereof.

[0218] 16. The method according to any one of inventive concepts 8-15, wherein the precursor solution has a storage stability against flow limitations of at least about 2 hours at room temperature, the storage stability being determined based on the precursor solution being injectable from a 5 ml syringe with a 25 gauge needle.

[0219] 17. The method according to any of inventive concepts 8-16, further comprising delivering an amount of the precursor solution to one or more additional patients to form one or more additional hydrogels, wherein the one or more additional hydrogels individually gel in no more than about 3 minutes.

[0220] 18. The method according to any one of inventive concepts 8-17, wherein delivering comprises injection by needle, high pressure needle-free injection, delivery through a catheter, delivery with a dropper, or spraying.

[0221] 19. The method according to any of inventive concepts 8-18, wherein delivering comprises multiple injections from a single barrel syringe, using the same needle or changing the needle between injections or a combination of both.

[0222] 20. The method according to any one of inventive concepts 8-19, further comprising assigning an expiration time after blending and discarding after expiration of the expiration time.

[0223] 21. The method according to any one of inventive concepts 8-20, wherein the physiologically significant tissue comprises an immune privileged space, a subcutaneous location, an ocular location, an intramural location, a body cavity, an abnormal tissue, a target tissue, or a combination thereof.

[0224] 22. The method of any of inventive concepts 8-21, wherein the delivery is to a tumor, fallopian tube, uterus, urethra, blood vessel, location within a muscle, location between a muscle and a nerve, eyelash line, or in and around the eye.

[0225] 23. The method according to any one of inventive concepts 8-22, wherein the delivery is monitored using a visualization agent.

[0226] 24. The method according to any one of inventive concepts 8-23, wherein the hydrogel gels in no more than 30 seconds.

[0227] 25. The method according to any one of inventive concepts 8-24, wherein the hydrogel degrades in no more than about 14 days.

[0228] 26. The method according to any one of inventive concepts 8-25, wherein the hydrogel releases a therapeutic amount of the therapeutic agent.

[0229] 27. The method according to inventive concept 26, wherein the therapeutic agent comprises analgesics, anesthetics, steroids, chemotherapeutic agents, glycosaminoglycans, carbohydrates, nucleic acids, proteins, anti-tumor drugs, glaucoma drugs, antibiotics, enzymes, anti-infective drugs, anti-fungal drugs, anti-inflammatory drugs, non-steroidal anti-inflammatory drugs, anti-tumor drugs, hormones, angiogenic agents, anti-angiogenic agents, growth factors, ocular hypotensive agents, antibodies, neurotransmitters, psychoactive drugs, anti-cancer drugs, drugs affecting fertility, genes, cells, cell products, oligonucleotides or combinations thereof.

[0230] 28. The method according to any of inventive concepts 8-27, wherein the hydrogel releases therapeutic amounts of the therapeutic agent for up to about 14 days.

[0231] 29. The method according to any of inventive concepts 8-27, wherein the hydrogel releases therapeutic amounts of the therapeutic agent for up to about 180 days.

[0232] 30. The method according to any of inventive concepts 8-27, wherein the hydrogel releases therapeutic amounts of the therapeutic agent for at least about 180 days.

[0233] 31. The method according to any one of inventive concepts 8-28, wherein the hydrogel degrades in no more than about 14 days.

[0234] 32. The method according to any one of inventive concepts 8-29, wherein the hydrogel degrades in no more than about 180 days.

[0235] 33. The method according to any of inventive concepts 8-30, wherein the hydrogel persists for at least about 180 days.

[0236] 34. The method according to any of inventive concepts 8-33, wherein multiple injections are performed to form the tattoo based on an aesthetic design.

[0237] 35. The method according to inventive concept 34, wherein the hydrogel comprises a covalently bonded dye.

[0238] 36. The method according to inventive concept 34, wherein the hydrogel persists for no more than about 180 days.

[0239] The above embodiments are intended to be illustrative and not restrictive. Additional embodiments are within the scope of the claims. In addition, although the present invention has been described with reference to particular embodiments, it will be appreciated by those skilled in the art that changes can be made in form and detail without departing from the spirit and scope of the present invention. Any incorporation by reference to the above-mentioned document is limited to not incorporating the subject matter that is contrary to the explicit disclosure of this article. In the sense of the specific structures, compositions and / or processes described herein with components, elements, ingredients or other parts, it should be understood that the disclosure herein covers these specific embodiments, embodiments comprising specific components, elements, ingredients, other parts or combinations thereof, and embodiments consisting essentially of such specific components, ingredients or other parts or combinations thereof, which may include additional features (as proposed in the discussion) that do not change the basic nature of the subject matter, unless otherwise expressly stated.

Claims

1. A medical hydrogel precursor solution, comprising an aqueous solvent having a pH of no greater than about 6, a first precursor comprising a plurality of electrophilic functional groups and a first hydrophilic core, and a mixture of a second precursor comprising a plurality of protonated amine groups, wherein the precursor solution is flowable for at least 10 minutes after formation and gels within 20 minutes after dilution with 1 / 3 volume of 37° C. phosphate buffered saline (PBS) (3 volumes of hydrogel precursor solution to 1 volume of PBS).

2. The medical hydrogel precursor solution according to claim 1, having a gel time of no more than about 3 minutes, wherein the gel time is measured in vitro by injecting a certain volume of the precursor solution at room temperature into a certain volume of PBS at 37°C, maintaining the combined volume at 37°C, and recording the time until a solid or semi-solid mass is formed, wherein the volume of the precursor solution and the volume of the PBS are equal.

3. The medical hydrogel precursor solution according to claim 1, having a gel time of about 10-40 seconds, wherein the gel time is measured in vitro by injecting a certain volume of the precursor solution at room temperature into a certain volume of PBS at 37°C, maintaining the combined volume at 37°C, and recording the time until a solid or semi-solid mass is formed, wherein the volume of the precursor solution and the volume of the PBS are equal.

4. The medical hydrogel precursor solution according to any one of claims 1 to 3, wherein the medical hydrogel precursor solution has a storage stability against flow restriction of at least about 10 minutes at room temperature, the storage stability being determined based on the precursor solution being injectable from a 5 ml syringe with a 27 gauge needle.

5. The medical hydrogel precursor solution of any one of claims 1-4, having no more than about 0.025 M of added buffer and having a storage stability against flow restriction of at least about 2 hours at room temperature, the storage stability being determined based on the precursor solution being injectable from a 5 ml syringe with a 25 gauge needle.

6. The medical hydrogel precursor solution according to any one of claims 1 to 5, wherein the aqueous solvent has no added buffer.

7. The medical hydrogel precursor solution according to any one of claims 1 to 5, wherein the aqueous solvent consists essentially of unbuffered saline or water for injection.

8. The medical hydrogel precursor solution according to any one of claims 1 to 7, wherein the first hydrophilic core and / or the second hydrophilic core comprises a polymer.

9. The medical hydrogel precursor solution according to any one of claims 1 to 7, wherein the first hydrophilic core and / or the second hydrophilic core comprises polyethylene glycol, polyvinyl alcohol, polyoxazoline, copolymers thereof or mixtures thereof.

10. The medical hydrogel precursor solution according to any one of claims 1 to 9, wherein the first hydrophilic core has a plurality of arms with electrophilic functional groups, the second hydrophilic core has a plurality of arms with protonated amine groups, or a combination thereof. The medical hydrogel precursor solution according to claim 10 , wherein the plurality of arms is 3 to 8.

12. The medical hydrogel precursor solution according to any one of claims 1 to 11, wherein the molecular weight of the second precursor is greater than or equal to the molecular weight of the first precursor.

13. The medical hydrogel precursor solution according to any one of claims 1-12, wherein the first precursor and the second precursor independently have a molecular weight of about 2K Da to about 50K Da and have 3 to 8 arms.

14. The medical hydrogel precursor solution according to any one of claims 1 to 13, wherein the electrophilic functional group comprises a reactive ester.

15. The medical hydrogel precursor solution according to any one of claims 1 to 13, wherein the electrophilic functional group comprises succinimidyl succinate, succinimidyl succinamide, succinimidyl glutarate, succinimidyl glutarate, succinimidyl adipate, succinimidyl azelate, or a combination thereof. 16 . The medical hydrogel precursor solution according to claim 1 , wherein the electrophilic functional group has a degradable ester bond with the first hydrophilic core or a non-degradable amide bond with the first hydrophilic core.

17. The medical hydrogel precursor solution of any one of claims 1-16, wherein the precursor solution has a solids concentration of at least about 1% by weight.

18. The medical hydrogel precursor solution of any one of claims 1-17, wherein the precursor solution has a solid concentration of no more than about 30% by weight.

19. The medical hydrogel precursor solution according to any one of claims 1-16, wherein the precursor solution has a solid concentration of about 8 wt% to about 17 wt%.

20. The medical hydrogel precursor solution according to any one of claims 1 to 19, further comprising a therapeutic agent.

21. The medical hydrogel precursor solution of claim 20, wherein the therapeutic agent comprises an analgesic, an anesthetic, a steroid, a chemotherapeutic, a glycosaminoglycan, a carbohydrate, a nucleic acid, a protein, an anti-tumor drug, a glaucoma drug, an antibiotic, a steroid, an enzyme, an anti-infective drug, an anti-fungal drug, an anti-inflammatory drug, a non-steroidal anti-inflammatory drug, an anti-tumor drug, a hormone, an angiogenic agent, an anti-angiogenic agent, a growth factor, an ocular hypotensive agent, an antibody, a neurotransmitter, a psychoactive drug, an anti-cancer drug, a drug that affects fertility, a gene, a cell, an oligonucleotide, or a combination thereof.

22. The medical hydrogel solution of claim 20, wherein the therapeutic agent comprises travoprost, a prostaglandin analog, a low solubility prostaglandin analog, a mydriatic agent, an anti-VEGF agent, an anti-VEGFR1 agent, an anti-VEGFR2 agent, an anti-VEGFR3 agent, an anti-PDGF agent, an anti-PDGF-R agent, an anti-PDGFRβ agent, sunitinib, E7080, Takeda-6d, tivozanib, regorafenib, sorafenib, pazopanib, axitinib, nintedanib, cediranib, vatal Ni, motesanib, macrolides, sirolimus, everolimus, tyrosine kinase inhibitors, imatinib, gefitinib, tocitanib, erlotinib, lapatinib, nilotinib bosutinib neratinib, lapatinib, vatalanib, dexamethasone, moxifloxacin, nepafenac, macrolides, rapamycin, sirolimus, tacrolimus, lipoic acid and derivatives, sterols, oxysterols, mRNA, chimeric antigen receptor cells, T cells, NK cells, gene-modified T cells, stem cells, pancreatic cells, or a combination thereof.

23. The medical hydrogel solution of claim 20, wherein the therapeutic agent comprises mRNA, chimeric antigen receptor cells, T cells, NK cells, genetically modified T cells, stem cells, pancreatic cells, or a combination thereof.

24. The medical hydrogel precursor solution according to any one of claims 1 to 23, further comprising a visualization agent.

25. The medical hydrogel precursor solution of claim 24, wherein the visualization agent is biocompatible and comprises a colorant, a fluorescent molecule, a contrast agent, or a combination thereof.

26. The medical hydrogel precursor solution of claim 25, wherein the visualization agent is covalently bonded to the first precursor, the second precursor, or a combination thereof.

27. The medical hydrogel precursor solution of claim 25, wherein the visualization agent comprises a reactive functional group capable of reacting with a nucleophilic functional group of the second precursor at an appropriate pH.

28. The medical hydrogel precursor solution according to any one of claims 1 to 27, further comprising a third precursor comprising a third hydrophilic core and a plurality of functional groups, wherein the plurality of functional groups comprise electrophilic functional groups or protonated amine groups.

29. The medical hydrogel precursor solution according to any one of claims 1-28, wherein the hydrogel formed from the precursor solution has a degradation time of no more than about 14 days, wherein the degradation time is measured in vitro by injecting a certain volume of the precursor solution at room temperature into a certain volume of PBS at 37°C, maintaining the combined volume at 37°C, and recording the time from the formation of a solid or semi-solid mass until the disappearance of the solid or semi-solid mass, wherein the volume of the precursor solution and the volume of the PBS are equal.

30. The medical hydrogel precursor solution according to any one of claims 1-29, wherein the hydrogel formed from the precursor solution has a degradation time of no more than about 180 days, wherein the degradation time is measured in vitro by injecting a certain volume of the precursor solution at room temperature into a certain volume of PBS at 37°C, maintaining the combined volume at 37°C, and recording the time from the formation of a solid or semi-solid mass until the disappearance of the solid or semi-solid mass, wherein the volume of the precursor solution and the volume of the PBS are equal.

31. The medical hydrogel precursor solution of claim 29, wherein a visualization agent is covalently bonded to the first precursor, the second precursor, or a combination thereof.

32. The medical hydrogel precursor solution according to any one of claims 1-31, wherein the hydrogel formed from the precursor solution has a degradation time of at least about 180 days, wherein the degradation time is measured in vitro by injecting a certain volume of the precursor solution at room temperature into a certain volume of PBS at 37°C, maintaining the combined volume at 37°C, and recording the time from the formation of a solid or semi-solid mass until the disappearance of the solid or semi-solid mass, wherein the volume of the precursor solution and the volume of the PBS are equal.

33. A dispenser comprising the medical hydrogel according to any one of claims 1-32.

34. The dispenser of claim 33, wherein the dispenser comprises a needle and a syringe.

35. The dispenser of claim 33, wherein the dispenser comprises a dropper.

36. The dispenser of claim 33, wherein the dispenser comprises a conduit.

37. The dispenser of claim 33, wherein the dispenser comprises a tattoo device.

38. A medical hydrogel precursor solution comprising a mixture of an aqueous solvent having a pH not exceeding about 6, a first precursor comprising a plurality of electrophilic functional groups and a first hydrophilic core, and a second precursor comprising a plurality of protonated amine groups and a second hydrophilic core.

39. A method for delivering an in situ cross-linked medical hydrogel, the method comprising: blending an electrophilic precursor and a nucleophilic precursor with an aqueous solvent having a pH of no greater than about 6 to form a precursor solution having a storage stability against mobility limitations of at least about 10 minutes at room temperature, the storage stability being determined by the precursor solution being injectable from a 5 ml syringe with a 25 gauge needle; as well as An amount of the precursor solution is delivered to a patient, wherein the precursor solution contacts physiological fluids associated with vital physiological tissue to induce cross-linking of the hydrogel, wherein the hydrogel gels in vivo in no more than about 5 minutes.

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