Sealants for tissue closure

Abstract

The present invention relates to a biodegradable two-layer sealant for tissue closure. The sealant of the present invention is composed of two layers with different compliances. The layer in direct contact with the tissue has high compliance. The second layer, located immediately above the first sealant layer, has low compliance, i.e., the sealant is much more rigid. The burst pressure of the two-layer sealant is increased compared to either a single-layer elastic sealant or a single-layer rigid sealant. The improved sealant composition herein provides a watertight seal, can access difficult-to-reach lacerations, can be applied in dry or wet environments, has low swelling, and can repair a range of incision or laceration sizes. The two-layer sealant is particularly useful for sutureless dural closure or as an adjunct to sutured dural closure. Methods for preparing and using the biodegradable sealant composition are also provided herein.

Description

[Technical Field]

[0001] The present invention relates to a biodegradable two-layer sealant composition for tissue closure and methods of use thereof. [Background technology]

[0002] Sutures, patches, implants, and sealants are used for tissue closure of wounds, lacerations, or surgical incisions. Implantable, biodegradable hydrogel sealants generally exhibit a high degree of swelling, which may make them unsuitable for medical applications around or near sensitive organs and tissues, or for neurosurgical and orthopedic spinal applications. Furthermore, there are few desirable sealant options for sealing sutured dural tissue, and currently no sealant options for sutureless dural closure.

[0003] Existing polyethylene glycol (PEG)-based hydrogel sealants (e.g., DURASEAL, Integra LifeSciences, Princeton, NJ, and ADHERUS, Hyperbranch Medical Technology, Durham, NC) are used as adjuncts to obtain a watertight seal after primary dural tissue closure, e.g., after the tissues are sutured. Such existing sealants are intentionally designed to provide a high crosslink density to reduce swelling, but can have undesirable brittle mechanisms. The high crosslink density is the result of including small molecule precursors, such as trilysine (e.g., in DURASEAL), or substrates, such as polyethyleneimine (e.g., in ADHERUS), that have a high density of reactive sites. Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need for a tissue closure sealant that forms a watertight seal, can access hard-to-reach lacerations, has low swelling, is flexible, and can repair a range of incision, wound, or laceration sizes. [Means for solving the problem]

[0005] Surprisingly and unexpectedly, the biodegradable and biocompatible two-layer sealant of the present invention reproduces many of the mechanical properties and advantages of adhesive patches. Provided herein is a biodegradable two-layer sealant comprising a first layer having an elastic composition and a second layer having a rigid composition. The elastic layer adheres and conforms to the underlying tissue as a result of tissue-like compliance, while the rigid layer reinforces and limits swelling of the elastic layer. The two-layer sealant combines the advantages of stand-alone elastic or rigid compositions. The elastic composition exhibits a high burst pressure but a high degree of swelling. The rigid composition is brittle and provides a poor sealant, but only a low degree of swelling. As a two-layer, the sealant exhibits both a high burst pressure and a low degree of swelling.

[0006] The bilayer sealants are useful for difficult-to-access surgical applications and medical procedures and surgeries involving sensitive organs and / or tissues, such as, but not limited to, neurosurgery, cranial surgery, spinal surgery, and orthopedic surgery. Additionally, the bilayer sealants herein are useful for primary and secondary tissue closure, for example, as an adjunct to suture closure, and for medical procedures and applications where sutures cannot be used or are undesirable. The bilayer sealants are particularly useful for sutureless primary dural closure in situations where suturing is difficult to access.

[0007] In some embodiments, the elastic polymer composition of the two-layer sealant comprises a hydrogel. In some aspects, the elastic layer comprises a crosslinkable macromolecular polymer hydrogel. In some embodiments, the elastic polymer composition comprises a polyethylene glycol (PEG) hydrogel. In some aspects of the invention, the elastic polymer composition is protein-free.

[0008] In other embodiments, the rigid polymer composition of the two-layer sealant comprises a hydrogel and at least one protein, peptide, or polypeptide. In some aspects, the hydrogel in the rigid layer comprises a PEG hydrogel. In other aspects, the rigid layer comprises one or more reactive macromolecular polymers and at least one protein, peptide, or polypeptide.

[0009] The terms "polypeptide," "peptide," and "protein" are used interchangeably herein to refer to a polymer of amino acid residues. That is, a description of a polypeptide applies equally to a description of a peptide and a description of a protein, and vice versa. These terms apply to naturally occurring amino acid polymers as well as amino acid polymers in which one or more amino acid residues are non-naturally encoded amino acids. As used herein, the terms apply to naturally occurring amino acid polymers as well as amino acid polymers in which one or more amino acid residues are non-naturally encoded amino acids. Polypeptides can also be modified by any of a variety of standard chemical methods (e.g., amino acids can be modified with protecting groups, the carboxy-terminal amino acid can be a terminal amide group, the amino-terminal residue can be modified with a group to increase, for example, lipophilicity, or the polypeptide can be chemically glycosylated or otherwise modified to increase stability or in vivo half-life). Polypeptide modifications can include the attachment of another structure, such as a cyclic compound or other molecule, to the polypeptide and can also include polypeptides containing one or more amino acids in a modified configuration (i.e., R or S, or L or D).

[0010] The terms "elastic," "flexible," and "flexing" are used interchangeably herein.

[0011] In other aspects, the rigid polymer composition comprises a reactive PEG precursor and a protein, hi some embodiments, the protein in the rigid layer is albumin, fibrinogen, ovalbumin, lactalbumin, an extracellular matrix protein, polylysine, collagen, gelatin, or a combination of two or more thereof.

[0012] In some embodiments, the two-layer sealant is sprayed or dripped onto the incision, laceration, or wound. In one embodiment, two separate single-component delivery devices can be used to apply the two-layer sealant to tissue, or a two-component or dual-barrel delivery device can be used to sequentially deliver the first and second layers of the two-layer sealant. In another embodiment, two separate dual-barrel delivery devices can be used to prepare the elastic and rigid polymer compositions, respectively, and then apply the elastic and rigid polymer compositions to tissue.

[0013] In another embodiment, a method for tissue closure is provided in which an elastic polymer composition is applied to tissue as a liquid solution. After at least partial gelation or curing of the elastic polymer composition on the tissue, a rigid polymer composition is applied as a liquid solution over the elastic polymer composition, forming a two-layer sealant after curing of the elastic and rigid polymer compositions.

[0014] Also provided is a method for tissue closure comprising: (a) applying a first layer onto dural tissue comprising a biodegradable elastic polymer composition comprising one or more reactive polyethylene glycols; (b) at least partially curing the first layer; and (c) applying a second layer over the surface of the first layer, the second layer comprising a biodegradable rigid polymer composition comprising one or more reactive polyethylene glycols and a protein. In another aspect, methods for using the biodegradable two-layer sealant of the present invention are provided for sutureless dural closure or as an adjunct to sutured dural closure.

[0015] In another embodiment of the present invention, a kit is provided having a first reservoir containing a biodegradable elastomeric polymer composition component and a second reservoir containing a biodegradable rigid polymer composition component for application to tissue to form a two-layer sealant, wherein the rigid polymer composition has a modulus of elasticity that is less than about three times that of the elastomeric polymer composition.

[0016] In another embodiment, provided herein is a method for making a bilayer sealant. In one aspect, a method for making a bilayer sealant for tissue closure is provided, the method comprising: (a) preparing an elastomeric polymer composition by combining a first solution comprising multi-armed PEG and a buffer with a second solution comprising multi-armed PEG in purified deionized water, and transferring the first and second solutions into separate 5 mL syringes in a first 10 mL dual-barrel syringe device; and (b) spraying about 1.5 to about 2 mL of the elastomeric polymer composition from the first 10 mL dual-barrel syringe device onto tissue to form a thickness of about 1.5 mm, allowing the elastomeric polymer composition to partially cure. (c) preparing a rigid polymer composition comprising combining a third solution of albumin in sodium carbonate buffer with a fourth solution of multi-arm PEG in purified deionized water; (d) transferring the third solution and the fourth solution into separate 5 mL syringes of a second 10 mL double-barrel syringe apparatus; and (e) spraying about 0.25 mL to about 0.5 mL of the rigid polymer composition from the second 10 mL double-barrel syringe apparatus onto the surface and edges of the partially cured elastomeric polymer composition to form a 0.5 mm thickness and allowing the bilayer sealant to cure.

[0017] Aspects and properties of elastic and rigid polymer compositions for obtaining novel two-ply sealants are provided herein.

[0018] In some embodiments, numbers expressing properties such as amounts of ingredients, molecular weights, reaction conditions, moduli, elongation at break, swelling ratios, concentrations, and results used to describe and claim particular embodiments of the present disclosure should be understood as being modified in some cases by the term "about." A person of ordinary skill in the art would understand the meaning of the term "about" in the context of the value it qualifies. In some embodiments, the term "about" is used to indicate that a value includes the standard deviation of the mean for the device or method being employed to determine the value. In some embodiments, the numerical parameters are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0019] As used herein, the words "comprising," "including," "having," and grammatical variations thereof are understood to specify the stated features, integers, steps, or components, but do not exclude the addition of one or more additional features, integers, steps, components, or groups thereof. These terms encompass the terms "consisting of" and "consisting essentially of." As used herein, the indefinite articles "a" and "an" mean "at least one" or "one or more," unless the context clearly dictates otherwise.

[0020] These and other aspects and advantages of the present invention will become more apparent from the following description and accompanying drawings. [Brief explanation of the drawings]

[0021] [Figure 1] 1 shows a cross section of a two-layer sealant composition of the present invention comprising an elastic polymer composition 10 applied over a dura mater and a rigid polymer composition 12 over the elastic polymer composition. [Figure 2A]1 is a graph showing burst pressure (mmHg) testing of a two-layer sealant composition of the present invention at various elastic layer to rigid layer ratios, as well as a first control composition having only the elastic composition and a second control composition having only the rigid composition. [Figure 2B] 1 is a graph of a normal distribution showing burst pressure at various percent thicknesses of the elastic (flexible hydrogel) layer of a two-layer composition of the present invention. [Figure 3] 1 is a graph showing percent swelling for two-layer sealant compositions of the present invention having various thickness ratios of elastic layer composition to rigid layer composition, as well as a first control of elastic layer composition only and a second control of rigid layer composition only. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention relates to a two-layer sealant that replicates many of the mechanical properties and advantages of adhesive patches in liquid sealants. The biodegradable and biocompatible two-layer sealant compositions provided herein can be utilized in difficult-to-access surgical applications. The two-layer sealant adheres to tissue and closes tissue tears or incisions without suturing or as an adjunct to sutured tissue. Surprisingly, the two-layer sealant not only provides a durable seal compared to using a stand-alone single-layer sealant composition, but also exhibits a reduced degree of swelling. The present invention provides a two-layer sealant comprising an elastic layer and a rigid layer to achieve a desirable novel high-burst-pressure, low-swell sealant suitable for sutureless tissue closure.

[0023] The dura mater, or dura mater, or dural tissue is a connective tissue that protects the brain and spinal cord. It is the outermost layer of the meninges. The dural tissue is subject to tears and dehydration. Alternatively, the dura may be intentionally incised and ruptured for subdural surgery. Both dural tears and intentional incisions can result in unwanted leakage of cerebrospinal fluid, which can lead to complications such as infection and meningitis.

[0024] The bilayer sealant of the present invention forms a watertight seal, can be used to repair difficult-to-reach lacerations, has low swelling properties, and can repair a range of dural incision or laceration sizes. The sealant composition disclosed herein provides the reliability surgeons desire, especially in tissues or areas where suturing is difficult or impossible. Furthermore, the bilayer sealant may shorten the duration of the operating room procedure by eliminating the need to suture the dura, thereby reducing surgical time. The bilayer sealant composition simplifies the dural closure procedure, shortens hospital stays, and minimizes postoperative complications.

[0025] There is a need for high-burst-pressure, low-swell sealants for suture- and sutureless tissue closure. Currently available PEG-based hydrogel sealants contain low-molecular-weight precursors, such as trilysine (e.g., DURASEAL®), or substrates, such as polyethyleneimine (e.g., ADHERUS®), to achieve high crosslink density due to low swelling. However, they suffer from brittle mechanics. Such fragile mechanics can lead to undesirable sealant failure when exposed to pressure peaks, such as when a patient sneezes, coughs, lifts a heavy object, or is subjected to a sudden impact.

[0026] The sealant of the present invention is composed of two layers with different compliances that are beneficial for primary dural closure. The elastic polymer composition in direct contact with the tissue is flexible and has high compliance similar to that of the dural tissue. The polymer composition located immediately above the first sealant layer has a higher stiffness.

[0027] Surprisingly, the biodegradable sealants provided herein have advantageously high burst strength in addition to strong tissue adhesion. The burst pressure of the two-layer sealant is increased compared to either a single-layer elastic sealant or a single-layer rigid sealant. The elastic layer allows the two-layer sealant to mimic the natural mechanics of the dura mater and conform well to the tissue. Meanwhile, the rigid layer provides a level of strain or elongation restriction for the two-layer sealant. This restriction is advantageous because it prevents the two-layer sealant from straining beyond its elongation upon failure.

[0028] The structural stiffness of a composition is essentially the thickness (T) weighted average of the elastic modulus (E), i.e., structural stiffness ∝ E 弾性 T 弾性 +E 剛性 T 剛性 Thus, the structural rigidity of the sealant bilayer can be adjusted by varying the thickness of each layer. Thus, if the overall thickness remains constant, increasing the thickness of the elastic layer decreases the overall rigidity, and increasing the thickness of the rigid layer increases the overall rigidity. Typically, increased elasticity correlates with increased swelling. The composite swelling of the bilayer sealant herein can be reduced compared to a single-layer elastic sealant composition. Swelling equilibrium occurs when the osmotic pressure caused by fluid inflow balances the resulting pressure generated by strain in the polymer molecules. The inclusion of a rigid layer increases resistance to osmotic pressure, reducing the degree of swelling at equilibrium.

[0029] In one embodiment, a method for tissue closure is provided in which a first elastic polymer composition is applied to the tissue as a liquid solution. After at least partial gelation or hardening of the first elastic polymer composition on the tissue, a rigid polymer composition is applied as a liquid over the elastic polymer composition.

[0030] A method for dural tissue closure is provided, comprising: (a) applying a first layer over the dural tissue, the first layer comprising a biodegradable elastic polymer composition; (b) at least partially curing the first layer; and (c) applying a second layer over the entire surface of the elastic polymer composition, the second layer comprising a biodegradable rigid polymer composition.

[0031] In one aspect, a method for dural tissue closure is provided, comprising: (a) applying a first layer onto the dural tissue, the first layer comprising a biodegradable elastic polymer composition comprising polyethylene glycol; (b) at least partially curing the first layer; and (c) applying a second layer over the entire surface of the elastic polymer composition, the second layer comprising a biodegradable rigid polymer composition comprising polyethylene glycol and a protein.

[0032] In some embodiments, the bilayer sealant composition provided herein is formed in situ. In some aspects, the bilayer sealant composition is sprayed or dripped onto a dural defect or incision. In other aspects, the elastic and rigid liquid sealant composition is applied with a syringe or other applicator. A suitable device for use in applying the sealant of the present invention allows application of the bilayer sealant onto dural tissue, allows uniform application of the bilayer sealant onto difficult-to-access tissue, prevents leakage of the liquid composition by providing a closed volume for containing fluid, and has a short fluid path, thereby eliminating and / or minimizing the risk of inlet blockage due to fluid bridging. Such a device allows a user, such as a surgeon or other medical professional, to uniformly apply the bilayer sealant composition of the present invention without leakage of material from the device, and eliminates or reduces the risk of the sealant composition hardening or crosslinking before it is applied to the tissue. A preferred device allows the desired volume of sealant to be applied, achieving an excellent seal and producing a seal of the desired height, width, and length to prevent leakage of cerebrospinal fluid through a dural tear or incision.

[0033] A variety of devices can be used to apply the first and second compositions, for example, two separate single-component delivery devices, or a two-component or double-barrel delivery device can be used for sequential delivery of the first and second layers of a two-layer sealant.

[0034] As used herein, the terms "cure" and "hardenable" in reference to a fluid composition refer to a composition that can undergo interactions among itself that result in an increase in the viscosity of the composition. Such interactions include polymerization and / or crosslinking of components, achieved with or without the use of an activator such as a catalyst, or a physical activator such as heat, radiation such as ultraviolet light, an electron beam, or a combination thereof.

[0035] Mixing of the elastomeric polymer composition components and contact with proteins / amines at the tissue interface after application of the elastomeric polymer composition to the tissue initiates curing of the elastomeric sealant and the formation of covalent bonds at the tissue interface. The partial gelation time of the elastomeric layer is approximately 30-60 seconds, after which 0.25-0.5 mL of the rigid polymer composition is applied by spraying or dripping to cover the entire surface and edges of the elastomeric layer to form a thickness of 0.5 mm. Mixing of the rigid polymer composition components and contact with the elastomeric sealant and tissue edges initiates curing of the rigid sealant, forming covalent bonds on the elastomeric sealant surface and at the tissue-edge interface.

[0036] The elastic layer is expandable, flexible, and has desirable swelling properties. Preferably, the elastic polymer composition is an expandable hydrogel, such as a PEG hydrogel or other polymeric hydrogel. Biodegradable hydrogels that degrade via hydrolysis are preferred for use in the sealant compositions described herein. In some embodiments, the layers of the bilayer sealant are linked via functional groups and / or linkers. In some embodiments, the elastic polymer composition is a hydrogel, and the rigid polymer composition comprises a crosslinker and one or more proteins. In some preferred embodiments, the hydrogel of the elastic polymer composition is a PEG hydrogel or other polymeric hydrogel, and the rigid polymer composition comprises PEG or other polymeric hydrogel and albumin or other suitable protein. In some aspects, the two layers are composed of compatible or mutually reactive chemicals that allow for covalent bonding between the two layers. For example, esters on PEG molecules in the elastic polymer composition form amide bonds with proteins in the rigid layer.

[0037] Multi-arm PEG suitable for the elastic layer can include 2, 3, 4, 6, or 8 multi-arm PEGs. For example, multi-arm PEGs are commercially available from Jenkem Technologies or NOF Corporation. In a preferred embodiment, the multi-arm PEG has a molecular weight of about 2 kDa to about 40 kDa. In some embodiments, PEG suitable for the elastic layer is a multi-arm PEG having a reactive functional group, such as an N-hydroxysuccinimide (NHS) ester group, at each end of an arm. At a pH of about 7 to about 10, the NHS ester groups of the PEG in the elastic layer and the primary amines of the protein in the rigid layer form a stable conjugate, i.e., an amide bond. Examples of PEG used in the elastic layer include 4-arm-PEG-succinimidyl glutarate (SG), 4-arm-PEG-succinimidyl valerate, 4-arm-PEG-succinimidyl carbonate, 4-arm-PEG-succinimidyl succinate, 4-arm-PEG-succinimidyl butanoate, 4-arm-PEG-succinimidyl succinamide, 4-arm-PEG-succinimidyl propionate, 4-arm-PEG-sulfosuccinimidyl glutarate (SG), and 4-arm-PEG-sulfosuccinimidyl glutarate (SG). Examples include 4-arm-PEG-sulfosuccinimidyl valerate, 4-arm-PEG-succinimidyl carbonate, 4-arm-PEG-succinimidyl carboxymethyl ester, 4-arm-PEG-sulfosuccinimidyl succinate, 4-arm-PEG-sulfosuccinimidyl butanoate, 4-arm-PEG-sulfosuccinimidyl succinamide, 4-arm-PEG-sulfosuccinimidyl propionate, and 4-arm-PEG-isocyanate, 4-arm-PEG-imidoester, and 4-arm-PEG-maleimide. Other examples include linear and 6-arm-PEGs of the chemistries listed above.

[0038] In some embodiments, the elastic layer is biosynthetic, for example, the elastic layer can include PEG-amine.

[0039] In another embodiment, thiols are suitable for use in the stiff layer and are reactive with PEG-NHS esters and PEG-maleimides suitable for use in the elastic layer.

[0040] In some embodiments, the elastic layer comprises a total concentration of PEG of about 80 mg / mL to about 200 mg / mL. In a preferred embodiment, the total concentration of PEG is about 124 mg / mL. Examples of preferred PEG for the elastic layer are 4-arm-PEG-succinimidyl glutarate, MW 20000 (4-arm-PEG-SG-20K) (62 mg / mL), available from JenKem Technologies or NOF Corporation, and 4-arm-PEG-Amine, MW 12000 (4-arm-PEG-NH 2 12K) (62 mg / mL), available from JenKem Technologies or NOF Corporation.

[0041] In some embodiments, the stiffness layer is biosynthetic or entirely biological, such as fibrin, fibrinogen, collagen and / or cellulose preparations.

[0042] Albumins for use in the rigid polymer composition of the bilayer sealant herein include bovine serum albumin (BSA), human serum albumin (HSA), recombinant human albumin, synthetic albumin, and albumin protein variants. Bovine serum albumin (BSA) is commercially available from several sources, for example, United States Pharmacopeia (USP) Reference Standard Bovine Serum Albumin is available from Sigma-Aldrich (St. Louis, Missouri). Recombinant human albumin, USP, is commercially available from several sources, for example, Sigma-Aldrich (St. Louis, Missouri).

[0043] In some embodiments, the stiff layer comprises albumin at a concentration of about 50 mg / mL to about 300 mg / mL. In a preferred embodiment, the concentration of albumin in the stiff layer composition is 150 mg / mL. In another embodiment, the stiff polymer composition comprises albumin or other suitable protein and PEG or other polymer.

[0044] Other proteins suitable for use in the rigid polymer composition include fibrin, ovalbumin, lactalbumin, collagen, gelatin, extracellular matrix proteins, and polylysine.

[0045] Other polymeric crosslinkers for use in the hydrogels of the two-layer sealants provided herein include functionalized polyethylene glycols.

[0046] In some embodiments, the elastic and rigid polymer compositions include additional components such as carbonate buffer, phosphate buffer, and phosphate buffered saline. In other embodiments, the polymer compositions herein include a buffer to adjust the pH of the composition to about pH 7 to about pH 10.

[0047] In some embodiments, the total thickness of the bilayer sealant is about 1.5 mm to about 5.0 mm. The central region of the bilayer sealant application site typically has a slightly thicker application than the edges of the bilayer sealant. The elastic layer is applied by spraying or dripping to the dural defect with reapproximated tissue at a thickness of 0.9 mm to about 1.95 mm. In some embodiments, the thickness of the bilayer sealant applied by spraying is about 1.5 mm to about 2.6 mm. In other embodiments, the thickness of the bilayer sealant applied by dripping is about 3.0 mm to about 5.0 mm. For example, a 2.2 mm total bilayer sealant thickness applied to the dura by spraying in a 1:1 ratio is 1.1 mm elastic layer to 1.1 mm rigid layer. In another aspect, a 2.2 mm total bilayer thickness applied by spraying in a 3:1 ratio is 1.65 mm elastic layer to 0.55 mm rigid layer.

[0048] The gel time of the elastic layer is about 30 to 60 seconds. The rigid layer can be applied about 1 to 2 minutes after the elastic layer. The rigid layer is then applied by spraying or dripping onto the surface of the elastic layer at a thickness of about 0.5 mm to about 1.3 mm. A preferred range of average diameter ratios of the two-layer sealant polymer compositions provided herein is about 1:1 elastic layer to rigid layer to about 3:1 elastic layer to rigid layer.

[0049] In some embodiments, degradation of the two-layer sealant occurs in less than about 8 weeks from application.

[0050] In another embodiment, the biodegradable sealant is characterized by a desirable burst pressure of at least 75 mmHg. For a two-layer sealant with a 3:1 elasticity:stiffness ratio, the average burst pressure is about 85.8 mmHg, ranging from about 53.7 mmHg to about 103.9 mmHg. For a two-layer sealant with a 1:1 elasticity:stiffness ratio, the average burst pressure is 110.5 mmHg, ranging from about 32.7 mmHg to about 141.3 mmHg. Existing dural sealants, DURASEAL and ADHERUS, used as adjuncts after primary dural closure, have average burst pressures of about 15.9 mmHg and 25.9 mmHg, respectively.

[0051] In another aspect, the elastic layer in a cured state has a modulus of elasticity (Young's modulus) of about 19.2 kPa to about 24.2 kPa. In one embodiment, the elastic polymer composition is characterized by an elongation at break of at least about 300%. In another embodiment, the layer of stiff polymer composition is characterized by a lower modulus than the elastic layer, such as about 33.4 kPa to about 47.6 kPa, and / or an elongation at break of about 40% to about 110%.

[0052] In a preferred embodiment, the elastic layer is characterized by an ultimate tensile stress of about 40 kPa to about 80 kPa, and an elongation at break of about 245% to 508%.

[0053] In one embodiment, the biodegradable two-layer sealant is characterized by a swelling ratio that is at least about 1.4 times lower than the swelling ratio of a single layer of the elastomeric polymer composition having the same thickness, as measured in an aqueous medium such as phosphate buffered saline (PBS) at 37° C. after 6 days. In another embodiment, the biodegradable sealant is characterized by a swelling ratio of about 70% to about 110%, as measured in an aqueous medium at 37° C. after 6 days.

[0054] In another embodiment, a method for making a bilayer sealant is provided herein. In one aspect, a method for making a bilayer sealant is provided, the method comprising: (a) preparing an elastic polymer composition comprising combining a first solution comprising 124 mg / mL of 4-arm-PEG-NH2-20K in about 200 mM N-cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer having a pH of about 9.35 and a second solution comprising 124 mg / mL of 4-arm-PEG-succinimidyl glutarate in purified deionized water, and transferring the first and second solutions into separate 5 mL syringes within a first 10 mL double-barrel syringe device; (b) spraying about 1.5 mL to about 2 mL of the elastic polymer composition from the first 10 mL double-barrel syringe device onto dura tissue to form a thickness of about 1.5 mm; (c) preparing a rigid polymer composition comprising combining a third solution of 300 mg / mL bovine serum albumin in about 200 mM sodium carbonate buffer having a pH of about 9.0 with a fourth solution of about 200 mg / mL 4-arm-PEG-succinimidyl glutarate in purified deionized water; (d) transferring the third and fourth solutions into separate 5 mL syringes of a second 10 mL double-barrel syringe device; and (e) spraying about 0.25 mL to about 0.5 mL of the rigid polymer composition from the second 10 mL double-barrel syringe device onto the surface and edges of the partially cured elastic polymer composition to create a thickness of 0.5 mm and allowing the bilayer sealant to cure.

[0055] In another embodiment, the elastic layer is configured to face and adhere to the tissue site. The swelling ratio of the two-layer sealant of the present invention is particularly advantageous for sealing dural tissue, compared to currently available dural sealants such as DURASEAL, which has a swelling ratio of about 200% under comparable conditions.

[0056] In one aspect, the two-layer sealants of the present invention provide an antimicrobial impermeable barrier. Additionally, the elastic layer of the two-layer sealants provided herein adheres to the dura tissue but advantageously does not adhere to other nearby tissues or organs.

[0057] In another embodiment of the present invention, a kit for applying an elastic polymer composition and a rigid polymer composition to tissue to form a two-layer sealant for tissue closure is provided, the kit including a first storage container containing a first solution and a second storage container containing a second solution for preparing a biodegradable elastic polymer composition component, and a third storage container containing a third solution and a fourth storage container containing a fourth solution for preparing a biodegradable rigid polymer composition component. In some aspects, the elastic polymer composition component of the kit includes polyethylene glycol, and the rigid polymer composition component of the kit includes polyethylene glycol and a protein, and the rigid polymer composition has an elastic modulus less than about three times that of the elastic polymer composition after application of the rigid polymer composition onto the surface of the elastic polymer composition and curing of the composition. The kit may optionally include four 5 mL syringes and two 10 mL double-barrel syringe devices.

[0058] In summary, the present invention encompasses, among other things, the following embodiments:

[0059] A first embodiment of the present disclosure relates to a biodegradable two-layer sealant for tissue closure, comprising a first layer comprising an elastic polymer composition and a second layer comprising a rigid polymer composition, wherein the layer thickness ratio of the elastic polymer composition to the rigid polymer composition is about 1:1 to about 3:1, respectively.

[0060] Embodiment 2: The two-layer sealant of embodiment 1, wherein the elastic polymer composition and the rigid polymer composition are linked by a covalent bond.

[0061] Embodiment 3: The two-layer sealant of embodiment 1 or 2, wherein the elastic polymer composition and / or the rigid polymer composition is a hydrogel.

[0062] Embodiment 4: The bilayer sealant of embodiment 3, wherein the hydrogel comprises mutually reactive polyethylene glycols.

[0063] Embodiment 5: The bilayer sealant of embodiment 4, wherein the polyethylene glycol is a multi-arm polyethylene glycol.

[0064] Embodiment 6: The two-layer sealant of any one of embodiments 1 to 5, wherein the rigid polymer composition further comprises a protein or peptide, and a cross-linking agent.

[0065] Embodiment 7: The bilayer sealant of embodiment 6, wherein the protein is albumin.

[0066] Embodiment 8: The bilayer sealant of embodiment 7, wherein the albumin is selected from the group consisting of bovine serum albumin, human serum albumin, recombinant human albumin, albumin protein variants, and synthetic albumins.

[0067] Embodiment 9: The bilayer sealant of embodiment 7, wherein the protein is selected from the group consisting of fibronectin, ovalbumin, lactalbumin, extracellular matrix proteins, polylysine, and combinations of two or more thereof.

[0068] Embodiment 10: The bilayer sealant of any one of embodiments 1 to 9, wherein the bilayer sealant has a burst pressure of at least about 80 mmHg.

[0069] Embodiment 11: The two-component sealant of any one of embodiments 1 to 10, wherein the elastic polymer composition has a modulus of elasticity of about 19 kPa to about 24 kPa.

[0070] Embodiment 12: The two-layer sealant of any one of embodiments 1 to 11, wherein the elastic polymer composition has an elongation at break of at least about 245%.

[0071] Embodiment 13: The two-layer sealant of any one of embodiments 1 to 12, wherein the rigid polymer composition has a modulus less than three times that of the elastic polymer composition and an elongation at break of about 100%.

[0072] Embodiment 14: A two-layer sealant described in any one of embodiments 1 to 13, wherein the sealant has a swelling ratio in an aqueous medium at 37°C after 6 days that is at least about 1.4 times lower than the swelling ratio in an aqueous medium at 37°C after 6 days of an elastic polymer composition having the same thickness.

[0073] Embodiment 15: A two-layer sealant according to any one of embodiments 1 to 14, wherein the sealant has a swelling ratio of about 70% to about 110% measured in an aqueous medium at 37°C after 6 days.

[0074] Embodiment 16 relates to a method for tissue closure, for example by creating a two-layer sealant, comprising: (a) applying a first layer onto tissue comprising a biodegradable elastomeric polymer composition comprising a multi-arm polyethylene glycol; (b) at least partially curing the first layer; and (c) applying a second layer on top of the elastomeric polymer composition, wherein the second layer comprises a biodegradable rigid polymer composition comprising a multi-arm polyethylene glycol and a protein or peptide.

[0075] Embodiment 17: The multi-arm polyethylene glycol is selected from the group consisting of 4-arm-PEG-amine, 4-arm-PEG-N-hydroxysuccinimide, 6-arm-PEG-N-hydroxysuccinimide, 4-arm-PEG-succinimidyl glutarate, 4-arm-PEG-succinimidyl carbonate, 4-arm-PEG-acrylate, 4-arm-PEG-succinimidyl valerate, 4-arm-PEG-succinimidyl succinate, 4-arm-PEG-succinimidyl butanoate, 4-arm-PEG-succinimidyl succinamide, 4-arm-PEG-succinimidyl propionate, 4-arm-PEG-sulfosuccinimidyl glutarate (S G), 4-arm-PEG-sulfosuccinimidyl valerate, 4-arm-PEG-sulfosuccinimidyl carbonate, 4-arm-PEG-succinimidyl carboxymethyl ester, 4-arm-PEG-sulfosuccinimidyl succinate, 4-arm-PEG-sulfosuccinimidyl butanoate, 4-arm-PEG-sulfosuccinimidyl succinamide, 4-arm-PEG-sulfosuccinimidyl propionate, and 4-arm-PEG-isocyanate, 4-arm-PEG-imidoester, and 4-arm-PEG-maleimide, and combinations of two or more thereof.

[0076] Embodiment 18: The method for tissue closure of embodiment 16 or 17, wherein the protein is selected from the group consisting of albumin, fibronectin, ovalbumin, lactalbumin, extracellular matrix proteins, polylysine, and combinations of two or more thereof.

[0077] Embodiment 19: A method for tissue closure described in any one of embodiments 16 to 18, wherein the ratio of layer thickness of the elastic polymer composition to the rigid polymer composition is about 1:1 to about 3:1, the elastic polymer composition has an elastic modulus of about 19 kPa to about 24 kPa, and the rigid polymer composition has an elastic modulus that is less than about 3 times that of the elastic polymer composition.

[0078] Embodiment 20 relates to a kit for preparing a biodegradable two-layer sealant for tissue closure, the kit comprising: a first storage container containing a first solution comprising multi-armed PEG in a cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer and a second storage container containing a second solution comprising multi-armed PEG in purified deionized water to prepare a biodegradable elastomeric polymer composition component; and a third storage container containing a third solution comprising a protein or peptide in a sodium carbonate buffer and a fourth storage container containing a fourth solution comprising multi-armed PEG in purified deionized water to prepare a biodegradable rigid polymer composition component, wherein after application of a rigid polymer composition onto a surface of the elastomeric polymer composition and curing of the elastomeric polymer composition and the rigid polymer composition, the rigid polymer composition has an elastic modulus that is less than about three times that of the elastomeric polymer composition.

[0079] Embodiment 21 relates to a method of making a bilayer sealant for tissue closure, comprising: (a) preparing an elastomeric polymer composition by combining a first solution comprising about 80 mg / mL to about 200 mg / mL of PEG-NH2-20K in about 200 mM N-cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer having a pH of about 9.35 and a second solution comprising about 80 mg / mL to about 200 mg / mL of 4-arm-PEG-succinimidyl glutarate in purified deionized water, and transferring the first and second solutions into separate 5 mL syringes in a first 10 mL double-barrel syringe device; and (b) spraying about 1.5 mL to about 2 mL of the elastomeric polymer composition from the first 10 mL double-barrel syringe device onto tissue to a thickness of about 1.5 mm, thereby forming a layer of the elastomeric polymer composition. (c) preparing a rigid polymer composition comprising combining a third solution of about 50 mg / mL to about 300 mg / mL of bovine serum albumin in about 200 mM sodium carbonate buffer having a pH of about 9.0 with a fourth solution of 80 mg / mL to about 200 mg / mL of 4-arm-PEG-succinimidyl glutarate in purified deionized water; (d) transferring each of the third and fourth solutions into separate 5 mL syringes of a second 10 mL double-barrel syringe device; and (e) spraying about 0.25 mL to about 0.5 mL of the rigid polymer composition from the second 10 mL double-barrel syringe onto the surface and edges of the partially cured elastomeric polymer composition to create a thickness of about 0.5 mm and allowing the bilayer sealant to cure.

[0080] Further details regarding the two-ply sealants of the present invention are provided in the non-limiting examples below. [Example]

[0081] The following materials were obtained for preparing and testing the bilayer sealants: 4-arm PEG-amine, MW20000 (4-arm-PEG-NH2-20K), from JenKem Technologies; 4-arm-PEG-succinimidyl glutarate, MW20000 (4-arm-PEG-SG-20K), from JenKem Technologies; bovine serum albumin from Sigma, sodium carbonate from Sigma; and N-cyclohexyl-2-aminoethanesulfonic acid (CHES) from Sigma. Test equipment included a pressure gauge (IP-073), a timer (EC-203), a caliper (ID-0164), and a standard syringe pump.

[0082] Example 1 Preparation of the elastic polymer composition of the two-layer sealant To prepare the elastic polymer composition of the two-layer sealant, first A 124 mg / mL 4-arm-PEG-amine, MW 20000 (4-arm-PEG-NH2-20K) solution is prepared in 200 mM N-cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer with a pH of approximately 9.35. Next, a 124 mg / mL 4-arm-PEG-succinimidyl glutarate, MW 20000 (4-arm-PEG-SG-20K) solution is prepared in purified deionized (DI) water. Each solution is then transferred to separate 5 mL Luer-Lock syringes, and a 10 mL double-barrel syringe apparatus equipped with a mixing tip is prepared for timed compression. The final concentration of the mixed elastomeric polymer composition is 62 mg / mL 4-arm-PEG-NHS-20K, 100 mM CHES, and 62 mg / mL 4-arm-PEG-SG-20K.

[0083] Example 2 Preparation of a two-layer sealant rigid polymer composition To prepare the rigid polymer composition of the bilayer sealant, first, a solution of 300 mg / mL bovine serum albumin, MW approximately 66 kDa (BSA), is prepared in 200 mM sodium carbonate buffer with a pH of approximately 9.0. Next, a solution of 200 mg / mL 4-arm-PEG-succinimidyl glutarate, MW 10,000 (4-arm-PEG-SG-10K) is prepared in purified DI water. Each solution is then transferred to separate 5 mL Luer-Lock syringes, and a 10 mL double-barrel syringe apparatus equipped with a mixing tip is prepared for timed compression. The final concentrations in the mixed sealant are 150 mg / mL BSA, 100 mM sodium carbonate, and 100 mg / mL 4-arm-PEG-SG-10K.

[0084] Example 3 Applying a first elastic polymer composition and a second rigid polymer composition to form a two-layer sealant.

[0085] Both the elastic and rigid polymer compositions are prepared in a 10 mL double-barrel syringe device, with the former squeezed out first. Approximately 1.5 mL to 2 mL of elastic sealant is applied via a spray or drop-in mixing tip over the reapproximated 15 mm linear dura / tissue laceration, creating a thickness of approximately 1.5 mm. Mixing of the components and contact with the protein / amine at the tissue interface initiates curing of the elastic sealant, forming covalent bonds at the tissue interface. The partial gelation time for this elastic layer is approximately 30 to 60 seconds, after which the rigid sealant can be applied next. Next, 0.25 mL to 0.5 mL of the rigid layer is applied by spray or drop-in, covering the entire surface and edges of the elastic layer, creating a thickness of 0.5 mm. Mixing of the rigid sealant components and contact with the protein / amine on the elastic sealant and tissue edge initiates curing of the rigid sealant, forming covalent bonds at the elastic sealant surface and tissue-edge interface. After curing, the average diameter ratio of the two-layer sealant polymer composition is approximately 3:1 for the elastic layer to the rigid layer. After 30-60 seconds, the elastic and rigid polymer compositions interconnect to form a two-layer sealant that continues to cure / strengthen over the next 10 minutes.

[0086] Example 4 Burst pressure test of sealant compositions Various sealant compositions were tested in a benchtop dural rupture pressure evaluation to evaluate various ratios of elastic to rigid polymer composition. A 15 mm linear incision was made in harvested porcine dura mater and reapproximated to simulate a clinical dural tear. Next, 1.5 mL to 2.0 mL or 1.5 mm to 2 mm thick layers of the elastic and rigid polymer compositions were tested separately as controls. The thickness of each layer was adjusted by varying the volume of each polymer composition applied to a fixed tissue area. A syringe pump was used to generate subsurface pressure at infusion rates of 2 to 10 mL / min, and the test was continued until failure. The peak pressure at failure and the failure mode were recorded for each sample. Failure modes were defined as cohesive failure within the sealant or adhesive failure at the foam-tissue interface. The results of the burst pressure tests are shown in Table 1 below, and the graph in Figure 2A shows the burst pressure (mmHg) test results for two-layer sealants of the present invention at various elastic to rigid layer ratios, as well as a first control composition having only the elastic polymer composition and a second control composition having only the rigid polymer composition. A preferred range of average diameter ratios for the provided two-layer sealant polymer compositions, compared to the controls, is from about 1:1 elastic to rigid layer to about 3:1 elastic to rigid layer.

[0087] [Table 1]

[0088] The results of burst pressure testing of bilayer sealants at various percent thicknesses of the elastomeric layer relative to the total bilayer sealant thickness are shown in the graph of Figure 2B.

[0089] It was observed that a thickness of about 50% elastomeric polymer composition increased the burst pressure compared to the control or two layer sealants having less than 50% or more than 50% elastomeric polymer composition.

[0090] Example 5 Swelling test of sealant composition Extent of swelling of sealant compositions having various ratios of elastomeric polymer composition to rigid polymer composition. The sealant compositions were applied to cylindrical molds and allowed to fully cure. The sealant compositions were then immersed in PBS at 37°C for 6 days. The percent swelling of the sealant compositions was assessed gravimetrically on days 1-6. The elastomeric polymer composition alone swelled up to 180%. The rigid polymer composition alone swelled up to 20%. Surprisingly, when the bilayer comprised of the rigid polymer composition was only 33% thick, the extent of swelling was reduced to about 100% (about 57% of the swelling observed with the elastomeric formulation alone). The results of the swelling test are shown in Table 2 below and in the graph of Figure 3.

[0091] [Table 2]

[0092] Example 6 Evaluation of the tensile properties of elastic and rigid sealant formulations To prepare the elastomeric polymer composition for the two-layer sealant, first prepare a 124 mg / mL solution of 4-arm-PEG-amine, MW 20000, in 200 mM N-cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer at pH 9.35. Next, prepare a 124 mg / mL solution of 4-arm-PEG-succinimidyl glutarate, MW 20000, in purified deionized (DI) water. The final concentrations of the mixed elastomeric polymer composition are 62 mg / mL 4-arm-PEG-NHS-20K, 100 mM CHES, and 62 mg / mL 4-arm-PEG SG-20K.

[0093] A Sulzer mixing drip tip was attached to the device, and the device was primed and then immediately squeezed into five tensile molds. The samples were loaded into an Instron testing machine and tested after a 10 minute cure time. The test was performed using a 10 N load cell, a 14.8 mm gauge length, and an 18.29 mm 2The test was completed using a mold to ensure a cross-sectional area of ​​1.0 mm and was run at a speed of 40.0 mm / min. The results of this experiment are summarized in Table 3 below.

[0094] [Table 3]

[0095] Although certain features of the invention are described, for clarity, in the context of separate embodiments, it is understood that they may also be provided in combination in a single embodiment. Conversely, various features of the invention, while for brevity described in the context of a single embodiment, may also be suitably provided separately or in any suitable subcombination, or in any other described embodiment of the invention. Certain features described in the context of various embodiments should not be construed as essential features of those embodiments, unless the embodiment is inoperable without those elements.

[0096] While various aspects of the present disclosure have been illustrated and described, further adaptations of the methods and systems described herein may be achieved by those skilled in the art through appropriate modifications without departing from the scope of the present invention. While some such possible modifications have been mentioned, other modifications will be apparent to those skilled in the art. For example, the embodiments, variations, geometries, materials, dimensions, proportions, steps, etc. discussed above are illustrative and not required. Accordingly, it will be understood that the scope of the present invention should be considered in terms of the following claims, and is not limited to the details of construction and operation shown and described in this specification and drawings.

[0097] [Embodiment] (1) A biodegradable two-layer sealant for tissue closure, comprising a first layer comprising an elastic polymer composition and a second layer comprising a rigid polymer composition, wherein the ratio of layer thickness of the elastic polymer composition to the rigid polymer composition is from about 1:1 to about 3:1, respectively. (2) The two-layer sealant of embodiment 1, wherein the elastic polymer composition and the rigid polymer composition are linked by a covalent bond. (3) The two-layer sealant of claim 1, wherein the elastic polymer composition and the rigid polymer composition are hydrogels. (4) The two-layer sealant of claim 3, wherein the hydrogel comprises mutually reactive polyethylene glycols. (5) The two-layer sealant of claim 4, wherein the polyethylene glycol is a multi-arm polyethylene glycol.

[0098] (6) The two-layer sealant of claim 1, wherein the rigid polymer composition further comprises a protein or peptide and a cross-linking agent. (7) The bilayer sealant of embodiment 6, wherein the protein is albumin. (8) The bilayer sealant of embodiment 7, wherein the albumin is selected from the group consisting of bovine serum albumin, human serum albumin, recombinant human albumin, albumin protein variants, and synthetic albumins. (9) The bilayer sealant of embodiment 6, wherein the protein is selected from the group consisting of fibronectin, ovalbumin, lactalbumin, extracellular matrix proteins, polylysine, and combinations of two or more thereof. (10) The bilayer sealant of claim 6, wherein the bilayer sealant has a burst pressure of at least about 10.67 kPa (about 80 mmHg).

[0099] (11) The two-component sealant according to claim 6, wherein the elastic polymer composition has a modulus of elasticity of about 19 kPa to about 24 kPa. (12) The two-component sealant of claim 6, wherein the elastic polymer composition has an elongation at break of at least about 245%. (13) The two-component sealant of claim 6, wherein the rigid polymer composition has a modulus less than three times that of the elastic polymer composition and an elongation at break of about 100%. (14) The two-layer sealant of claim 6, wherein the sealant has a swelling ratio in an aqueous medium at 37°C after 6 days that is at least about 1.4 times lower than the swelling ratio of the elastic polymer composition having the same thickness in an aqueous medium at 37°C after 6 days. (15) The two-layer sealant of embodiment 6, wherein the sealant has a swelling ratio of about 70% to about 110% measured in an aqueous medium at 37°C after 6 days.

[0100] (16) A method for tissue closure, comprising: (a) applying to tissue a first layer comprising a biodegradable elastomeric polymer composition comprising a multi-arm polyethylene glycol; (b) at least partially curing the first layer; and (c) applying a second layer over the surface of the elastomeric polymer composition, wherein the second layer comprises a biodegradable rigid polymer composition comprising a multi-arm polyethylene glycol and a protein or peptide. (17) The multi-arm polyethylene glycol is 4-arm-PEG-amine, 4-arm-PEG-N-hydroxysuccinimide, 6-arm-PEG-N-hydroxysuccinimide, 4-arm-PEG-succinimidyl glutarate, 4-arm-PEG-succinimidyl carbonate, 4-arm-PEG-acrylate, 4-arm-PEG-succinimidyl valerate, 4-arm-PEG-succinimidyl succinate, 4-arm-PEG-succinimidyl butanoate, 4-arm-PEG-succinimidyl succinamide, 4-arm-PEG-succinimidyl propionate, 4-arm-PEG-sulfosuccinimidyl glutarate (SG), 4-arm-PEG-sulfosuccinimidyl valerate, 4-arm-PEG-sulfosuccinimidyl carbonate, 4-arm-PEG-succinimidyl carboxymethyl ester (4-arm-PEG-succinimidyl carboxymethyl ester), 4-arm-PEG-sulfosuccinimidyl succinate, 4-arm-PEG-sulfosuccinimidyl butanoate, 4-arm-PEG-sulfosuccinimidyl succinamide, 4-arm-PEG-sulfosuccinimidyl propionate, and 4-arm-PEG-isocyanate, 4-arm-PEG-imidoester, and 4-arm-PEG-maleimide, and combinations of two or more thereof. (18) The method of embodiment 16, wherein the protein is selected from the group consisting of albumin, fibronectin, ovalbumin, lactalbumin, extracellular matrix proteins, polylysine, and combinations of two or more thereof. 19. The method of claim 16, wherein the layer thickness ratio of the elastic polymer composition to the rigid polymer composition is from about 1:1 to about 3:1, the elastic polymer composition has a modulus of from about 19 kPa to about 24 kPa, and the rigid polymer composition has a modulus of less than about 3 times that of the elastic polymer composition. (20) A kit for preparing a biodegradable two-layer sealant for tissue closure, comprising: a first storage container containing a first solution comprising multi-armed PEG in a cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer and a second storage container containing a second solution comprising multi-armed PEG in purified deionized water to prepare a biodegradable elastomeric polymer composition component; and a third storage container containing a third solution comprising a protein or peptide in a sodium carbonate buffer and a fourth storage container containing a fourth solution comprising multi-armed PEG in purified deionized water to prepare a biodegradable rigid polymer composition component, wherein after application of the rigid polymer composition onto the surface of the elastomeric polymer composition and curing of the elastomeric polymer composition and the rigid polymer composition, the rigid polymer composition has an elastic modulus that is less than about three times that of the elastomeric polymer composition.

Claims

1. A biodegradable two-layer sealant for tissue closure, comprising a first layer comprising an elastic polymer composition and a second layer comprising a rigid polymer composition, wherein the ratio of layer thickness of the elastic polymer composition to the rigid polymer composition is from about 1:1 to about 3:1, respectively.

2. The two-component sealant of claim 1 , wherein the elastic polymer composition and the rigid polymer composition are linked by a covalent bond.

3. The two-component sealant of claim 1 , wherein the elastic polymer composition and the rigid polymer composition are hydrogels.

4. The two-layer sealant of claim 3 , wherein the hydrogel comprises mutually reactive polyethylene glycols.

5. The two-layer sealant of claim 4 wherein the polyethylene glycol is a multi-arm polyethylene glycol.

6. The two-layer sealant of claim 1 , wherein the rigid polymer composition further comprises a protein or peptide and a cross-linking agent.

7. The two-layer sealant of claim 6 wherein the protein is albumin.

8. 8. The bilayer sealant of claim 7, wherein the albumin is selected from the group consisting of bovine serum albumin, human serum albumin, recombinant human albumin, albumin protein variants, and synthetic albumins.

9. 7. The bilayer sealant of claim 6, wherein the protein is selected from the group consisting of fibronectin, ovalbumin, lactalbumin, extracellular matrix proteins, polylysine, and combinations of two or more thereof.

10. 7. The two-layer sealant of claim 6, wherein the two-layer sealant has a burst pressure of at least about 80 mmHg.

11. The two-component sealant of claim 6, wherein the elastic polymer composition has a modulus of elasticity of about 19 kPa to about 24 kPa.

12. 7. The two-component sealant of claim 6, wherein the elastic polymer composition has an elongation at break of at least about 245%.

13. 7. The two-component sealant of claim 6, wherein said rigid polymer composition has a modulus less than three times that of said elastic polymer composition and an elongation at break of about 100%.

14. 7. The two-layer sealant of claim 6, wherein the sealant has a swelling ratio in an aqueous medium at 37°C after 6 days that is at least about 1.4 times lower than the swelling ratio of the elastic polymer composition having the same thickness in an aqueous medium at 37°C after 6 days.

15. 7. The two-layer sealant of claim 6, wherein the sealant has a swelling ratio of about 70% to about 110% measured in an aqueous medium at 37°C after 6 days.

16. A method for tissue closure, comprising: (a) applying a first layer to tissue, the first layer comprising a biodegradable elastic polymer composition comprising a multi-arm polyethylene glycol; (b) at least partially curing the first layer; and (c) applying a second layer over the surface of the elastic polymer composition, the second layer comprising a biodegradable rigid polymer composition comprising a multi-arm polyethylene glycol and a protein or peptide.

17. The multi-arm polyethylene glycol is 4-arm-PEG-amine, 4-arm-PEG-N-hydroxysuccinimide, 6-arm-PEG-N-hydroxysuccinimide, 4-arm-PEG-succinimidyl glutarate, 4-arm-PEG-succinimidyl carbonate, 4-arm-PEG-acrylate, 4-arm-PEG-succinimidyl valerate, 4-arm-PEG-succinimidyl succinate, 4-arm-PEG-succinimidyl butanoate, 4-arm-PEG-succinimidyl succinamide, 4-arm-PEG-succinimidyl propionate, 4-arm-PEG-sulfosuccinimidyl glutarate, 17. The method of claim 16, wherein the PEG-14 alkyl ester is selected from the group consisting of 4-arm-PEG-sulfosuccinimidyl valerate, 4-arm-PEG-sulfosuccinimidyl carbonate, 4-arm-PEG-succinimidyl carboxymethyl ester, 4-arm-PEG-sulfosuccinimidyl succinate, 4-arm-PEG-sulfosuccinimidyl butanoate, 4-arm-PEG-sulfosuccinimidyl succinamide, 4-arm-PEG-sulfosuccinimidyl propionate, and 4-arm-PEG-isocyanate, 4-arm-PEG-imidoester, and 4-arm-PEG-maleimide, and combinations of two or more thereof.

18. 17. The method of claim 16, wherein the protein is selected from the group consisting of albumin, fibronectin, ovalbumin, lactalbumin, extracellular matrix proteins, polylysine, and combinations of two or more thereof.

19. 17. The method of claim 16, wherein the ratio of layer thickness of the elastic polymer composition to the rigid polymer composition is from about 1:1 to about 3:1, the elastic polymer composition has a modulus of from about 19 kPa to about 24 kPa, and the rigid polymer composition has a modulus of less than about 3 times that of the elastic polymer composition.

20. 1. A kit for preparing a biodegradable two-layer sealant for tissue closure, the kit comprising: a first storage container containing a first solution comprising a multi-arm PEG in a cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer and a second storage container containing a second solution comprising the multi-arm PEG in purified deionized water to prepare a biodegradable elastomeric polymer composition component; and a third storage container containing a third solution comprising a protein or peptide in a sodium carbonate buffer and a fourth storage container containing a fourth solution comprising the multi-arm PEG in purified deionized water to prepare a biodegradable rigid polymer composition component, wherein after application of the rigid polymer composition onto the surface of the elastomeric polymer composition and curing of the elastomeric polymer composition and the rigid polymer composition, the rigid polymer composition has an elastic modulus that is less than about three times that of the elastomeric polymer composition.

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