Plasma activated hydrogel spacer, preparation method and application

Abstract

The invention relates to the technical field of tumor radiotherapy auxiliary instruments, biomedical materials and plasma medicine, in particular to a plasma activated hydrogel spacer for intracavity close-range radiotherapy, a preparation method and application. A plasma activated hydrogel spacer for implantation between a tumor tissue and an organ at risk, comprising a three-dimensional network of biocompatible and degradable hydrogel, and RONS introduced by plasma activation and capable of controlled release at 37 DEG C. According to the technical scheme, the plasma activated hydrogel spacer has the advantages that the dosage of OARs is reduced, RONS sensitization on tumors is achieved, the plasma activated hydrogel spacer is degradable, secondary taking-out is not needed, parameters are adjustable, the activation and forming process is simple, and the dosimetry disturbance result is achieved; and the clinical feasibility is high.

Description

Technical Field

[0001] This invention relates to the fields of auxiliary devices for tumor radiotherapy, biomedical materials and plasma medicine technology, specifically to a plasma-activated hydrogel spacer for intracavitary brachytherapy, its preparation method and application. Background Technology

[0002] Intracavitary brachytherapy, when treating tumors such as cervical cancer, is susceptible to cumulative dose limitations due to the presence of organs at risk (OARs) such as the bladder, rectum, and small intestine. Existing absorbable / hydrogel spacers are mostly "passive spacers," lacking active therapeutic capabilities. While plasma-activated RONS (RONS) generated by cold plasma (CAP) can enhance tumor radiosensitivity, direct in vivo irradiation is constrained by equipment and safety limitations. Plasma-activated hydrogels (PAHs) can load and sustain long-life RONS, but there is currently no mature technical solution to couple them with radiotherapy spacers, simultaneously achieving physical isolation and biosensitization. Summary of the Invention

[0003] The purpose of this invention is to provide a plasma-activated hydrogel spacer, its preparation method, and its application, thereby achieving an implantable spacer that combines physical isolation with RONS biosensitization, is biodegradable, image-visualizable, and compatible with brachytherapy, as well as a reproducible preparation method and in-hospital components, controlling dose perturbations and improving clinical feasibility, in order to solve the problems existing in the above-mentioned background art.

[0004] To achieve the above objectives, this application employs the following technical solution:

[0005] A plasma-activated hydrogel spacer for implantation between tumor tissue and organs at risk includes a biocompatible and degradable three-dimensional hydrogel network and RONS introduced by plasma activation and released in a controlled manner at 37°C.

[0006] The spacer satisfies the following parameter combination:

[0007] a) At 37°C, the apparent half-life of RONS release is 6-72 hours;

[0008] b) The storage modulus G' of the hydrogel is 1–50 kPa;

[0009] c) The spacer degrades in vivo in 4-12 weeks;

[0010] d) The spacer is compatible with intracavitary brachytherapy devices, and the perturbation of the planned dose within the clinical treatment energy range is less than 3%.

[0011] Furthermore, the hydrogel matrix is ​​selected from one or more of polyethylene glycol diacrylate, methacrylamide gelatin, alginate, hyaluronic acid, chitosan and polyvinyl alcohol, and the hydrogel matrix has a dual network structure.

[0012] Furthermore, in the dual-network structure, the first network is a photocrosslinking network of PEGDA or GelMA, and the second network is alginate-Ca... 2+ Ion cross-linked network.

[0013] Furthermore, the surface of the hydrogel matrix has microtextures or through-pores to improve tissue anchoring and uniformity of RONS release.

[0014] Furthermore, the initial content of the RONS satisfies the following conditions: hydrogen peroxide is 10-1000 μM, and / or nitrite is 10-1000 μM.

[0015] Furthermore, the RONS release curves were fitted by the Higuchi model or the Fick diffusion model, and the effective concentration range was maintained for 48–168 hours at 37 °C.

[0016] Furthermore, the energy storage modulus G' is preferably 5–25 kPa, the compressive strength is ≥10 kPa, and the failure strain is ≥20%.

[0017] Furthermore, the spacer also includes 0.1-20 wt% of a medical imaging contrast agent to achieve image localization, wherein the contrast agent is selected from iodine contrast agent, barium sulfate or tantalum powder.

[0018] Furthermore, the spacer contains a hydrophilic, radiopaque filler and is visible under CT or fluoroscopic imaging without significantly affecting dose distribution.

[0019] Furthermore, the spacer is in the form of a sheet, wedge, or block, with a length of 1–5 cm and a thickness of 0.5–2 cm; or it is an injectable gel-forming form adapted to 18–22G injection needles.

[0020] A method for preparing a plasma-activated hydrogel spacer involves using dielectric barrier discharge or plasma jet to activate a solvent or hydrogel precursor solution with a power of 1–30 W for 1–20 min, followed by the introduction of RONS to obtain a plasma-activated hydrogel spacer, or cross-linking a RONS-containing solution with a hydrogel precursor to obtain a plasma-activated hydrogel spacer.

[0021] Furthermore, the activating gas is argon, or argon-oxygen, wherein the volume percentage of oxygen is 0.1%-5%, or helium or air, the flow rate of the activating gas is 1-15 L / min, and the activation time is 0.5-5 min / 10 mL.

[0022] Furthermore, the crosslinking is photocuring and / or ionic crosslinking, wherein photocuring is performed by irradiation with a 365–405 nm light source for 10–600 s, and the photoinitiator is Irgacure 2959 or LAP, with an addition amount of 0.05–0.5 wt%; the ionic crosslinking is alginate-Ca 2+ Ionic crosslinking was performed by treating with 10–100 mM CaCl2 solution for 1–10 min.

[0023] Furthermore, 0.1–20 wt% developer is added during the plasma-activated hydrogel spacer molding stage.

[0024] Application of a plasma-activated hydrogel spacer, the use of the plasma-activated hydrogel spacer of any of the above in brachytherapy equipment for tumors.

[0025] The beneficial effects of this invention are:

[0026] The plasma-activated hydrogel spacer of this technical solution simultaneously reduces the dose of OARs and enhances RONS sensitization of tumors. It is degradable, requires no secondary removal, has adjustable parameters, a simple activation and molding process, and has a dosimetric perturbation of <3%, making it highly clinically feasible. Detailed Implementation

[0027] The technical solutions of the present invention will be described in detail below through embodiments. The following embodiments are merely exemplary and can only be used to explain and illustrate the technical solutions of the present invention, and should not be construed as limiting the technical solutions of the present invention.

[0028] This application provides a plasma-activated hydrogel spacer for implantation between tumor tissue and organs at risk, comprising a biocompatible and degradable three-dimensional hydrogel network, and RONS introduced by plasma activation and released in a controlled manner at 37°C.

[0029] The spacer satisfies the following parameter combination:

[0030] a) At 37°C, the apparent half-life of RONS release is 6-72 hours.

[0031] b) The hydrogel has a storage modulus G' of 1–50 kPa, preferably 5–25 kPa, a compressive strength ≥10 kPa, and a failure strain ≥20%.

[0032] c) The spacer degrades in vivo in 4-12 weeks.

[0033] d) The spacer is compatible with intracavitary brachytherapy devices, and the perturbation of the planned dose within the clinical treatment energy range is less than 3%.

[0034] In this application, the hydrogel matrix is ​​selected from one or more of polyethylene glycol diacrylate, methacrylamide gelatin, alginate, hyaluronic acid, chitosan, and polyvinyl alcohol, and the hydrogel matrix has a dual-network structure. In the dual-network structure, the first network is a photocrosslinking network of PEGDA or GelMA, and the second network is alginate-Ca... 2+ Ion cross-linked network.

[0035] In this application, the surface of the hydrogel matrix has microtextures or through-holes to improve tissue anchoring and uniformity of RONS release.

[0036] In this application, the initial concentration of RONS meets the following requirements: hydrogen peroxide 10-1000 μM and / or nitrite 10-1000 μM. The RONS release curve is fitted by the Higuchi model or the Fick diffusion model, and the effective concentration range is maintained at 37 °C for 48–168 hours.

[0037] In this application, the spacer also includes 0.1-20 wt% of a medical imaging contrast agent to achieve image localization, wherein the contrast agent is selected from iodine contrast agent, barium sulfate or tantalum powder.

[0038] In this application, the spacer contains a hydrophilic, radiopaque filler and is visible under CT or fluoroscopic images, without significantly affecting dose distribution.

[0039] In this application, the spacer is in the form of a sheet, wedge, or block, with a length of 1–5 cm and a thickness of 0.5–2 cm; or it is an injectable, in-situ gel-forming form, adapted to 18–22G injection needles.

[0040] This application also provides a method for preparing a plasma-activated hydrogel spacer. The method involves using dielectric barrier discharge or a plasma jet to activate a solvent or hydrogel precursor solution with a power of 1–30 W for 1–20 min. Then, RONS is introduced to obtain a plasma-activated hydrogel spacer, or a solution containing RONS is cross-linked with the hydrogel precursor to obtain a plasma-activated hydrogel spacer. The activating gas is argon, or argon-oxygen, wherein the oxygen volume percentage is 0.1%–5%, or helium or air, with a gas flow rate of 1–15 L / min and an activation time of 0.5–5 min / 10 mL. Cross-linking is performed by photocuring and / or ionic cross-linking. Photocuring uses a 365–405 nm light source for 10–600 s, with Irgacure 2959 or LAP as the photoinitiator, added at an amount of 0.05–0.5 wt%. Ionic cross-linking is performed using alginate-Ca... 2+ Ionic crosslinking was performed by treating with 10–100 mM CaCl2 solution for 1–10 min.

[0041] In this application, 0.1–20 wt% of developer is added during the plasma-activated hydrogel spacer molding stage.

[0042] This application also provides an application of a plasma-activated hydrogel spacer, the use of any of the above-mentioned plasma-activated hydrogel spacers in brachytherapy products for tumors.

[0043] In this application, the plasma-activated hydrogel includes two preparation routes: indirect activation: CAP preparation of PAW → precursor solvent preparation → photocuring / ionic crosslinking → formation of PAH; and direct activation: precursor solution directly accepts CAP → photocuring / ionic crosslinking → formation of PAH.

[0044] Example 1 (Indirect activation of GelMA / alginic acid dual-network sheet)

[0045] Plasma activated water (PAW) was obtained by treating 500 mL of sterile water with an argon flow rate of 10 L / min and an 8 W plasma jet for 10 min, containing approximately 100–300 μM H2O2 and approximately 50–200 μM NO2-.

[0046] GelMA (10 wt%), sodium alginate (1.5 wt%), and LAP (0.1 wt%) were dissolved in PAW to obtain a hydrogel precursor. The precursor was poured into a sterile mold and irradiated with 405 nm light for 60 s; then it was placed in 50 mM CaCl2 for 5 min. The dimensions were approximately 30 × 20 × 10 mm.

[0047] The performance of plasma-activated hydrogels was tested as follows: G' approximately 10–20 kPa; RONS release in PBS at 37 °C for t1 / 212–36 h; degradation mass loss ≥80% over 4–8 weeks.

[0048] Example 2 (Direct Activation - PEGDA Injectable In-Situ Gel Formation)

[0049] A hydrogel precursor solution was prepared by using 15 wt% PEGDA (Mn≈700), 0.2 wt% Irgacure 2959, and PBS as solvents.

[0050] The hydrogel precursor solution was directly activated using an argon-oxygen mixture (1% oxygen content) at 12 W for 3 min on 10 mL of the precursor solution. After injection into the target interstitial space with a 20G needle, in vivo cross-linking was completed by irradiation with 405 nm light for 60 s.

[0051] The performance of plasma-activated hydrogels was tested as follows: initial H2O2 100–400 μM; t1 / 2 6–24 h; G' 5–15 kPa; basic degradation in 6–10 weeks.

[0052] Example 3 (Development and Dosimetric Assessment)

[0053] Adding 5 wt% barium sulfate microparticles (D50 < 10 μm) to the hydrogel matrix formulation of Example 1 improved the CT value. Evaluation using a water phantom and ionization chamber / Monte Carlo method showed a dose perturbation of < 3% at clinical energies.

[0054] Example 4 (Characteristics of Release and Network Interactions)

[0055] Amplex Red (H2O2), Griess (NO 2- ); PBS at 37 ℃, sampling from 0 to 168 h; Higuchi / Fick model, recording fitting parameters and R²; FTIR / XPS observation of changes in amine / carboxyl and other related peaks after CAP treatment, indicating the interaction between RONS and the network.

[0056] Example 5 (In Vitro Functional Performance Testing Protocol)

[0057] Using HeLa / SiHa cells, the Serous Return (SER) was calculated by combining plasma-activated hydrogel extract with radiotherapy clonogenesis assay. ROS and DNA damage were tested using DCFH-DA flow cytometry and γ-H2AX immunofluorescence.

[0058] t1 / 2 was calculated using Amplex Red / Griess, PBS at 37 °C, and RONS quantification and release were determined by Higuchi / Fick fitting and R² testing.

[0059] In this application, low-temperature plasma (CAP) treatment of water / buffer water can stably generate hydrogen peroxide (H2O2) and nitrite (NO3). 2- It is a long-lived species, mainly composed of [a specific species], with concentrations typically in the μM–mM range, and exhibits measurable stability under conditions of light protection, suitable pH, and ionic strength. When introduced into a hydrogel system, it can achieve sustained release through diffusion-reaction kinetics.

[0060] In hydrogels with uniform thickness, uniform initial loading, and relatively stable diffusion coefficient, small molecules (such as H2O2, NO) can... 2- The release of the product can be well described by Fick diffusion or its approximate Higuchi model; when the network density and water content are within the typical range of medical hydrogels, the release half-life can be modulated to several hours to tens of hours by the degree of crosslinking, dual network configuration and microstructure (pores / microtexture).

[0061] Exogenous RONS can increase intracellular ROS homeostasis and amplify ionizing radiation-induced DNA double-strand breaks and oxidative damage, manifested as increased γ-H2AX focal points, cell cycle G2 / M arrest, and decreased colony formation survival. Under low-to-medium μM exogenous H2O2 / NO2- window, tumor cells are more sensitive to radiotherapy, while reversible effects on adjacent normal tissues can be controlled by dose / time window and spatial sustained release.

[0062] The storage modulus G' of medical hydrogel systems such as PEGDA / GelMA / alginic acid is controllable within the range of 1–50 kPa, and a balance can be achieved between "sufficient shaping / anchoring" and "tissue compatibility / degradability" in the range of 5–25 kPa; the dual network (photocrosslinking + Ca) 2+ Ions help to improve initial strength and release adjustability without significantly sacrificing water content.

[0063] In clinical energy (e.g.) 192 At the Ir scale and millimeter-scale geometry, dose perturbations of low Z or thin-layer low-volume-fraction fillers (such as 0.1–20 wt% barium sulfate / iodine contrast agent / tantalum powder) can be controlled within 3%; radiopaque fillers have been adopted in various medical implants and spacers for intraoperative positioning and imaging verification.

[0064] Materials such as PEG, GelMA, alginate, and hyaluronic acid have been widely used in biodegradable medical products; a degradation window of 4–12 weeks can be obtained by adjusting molecular weight, crosslinking density, and network configuration; combined with in-hospital components and aseptic processes, reproducible preparation and clinical implantation procedures can be achieved.

[0065] The above description is merely an embodiment of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A plasma-activated hydrogel spacer for implantation between tumor tissue and organs at risk, characterized in that, This includes a biocompatible and biodegradable three-dimensional hydrogel network, and RONS introduced by plasma activation and released in a controlled manner at 37°C; The spacer satisfies the following parameter combination: a) At 37°C, the apparent half-life of RONS release is 6-72 hours; b) The storage modulus G' of the hydrogel is 1–50 kPa; c) The spacer degrades in vivo in 4-12 weeks; d) The spacer is compatible with intracavitary brachytherapy devices, and the perturbation of the planned dose within the clinical treatment energy range is less than 3%.

2. The plasma-activated hydrogel spacer according to claim 1, characterized in that, The hydrogel matrix is ​​selected from one or more of polyethylene glycol diacrylate, methacrylamide gelatin, alginate, hyaluronic acid, chitosan and polyvinyl alcohol, and the hydrogel matrix has a double network structure.

3. The plasma-activated hydrogel spacer according to claim 2, characterized in that, In the dual-network structure, the first network is a photocrosslinking network of PEGDA or GelMA, and the second network is alginate-Ca. 2+ Ion cross-linked network.

4. The plasma-activated hydrogel spacer according to claim 2, characterized in that, The surface of the hydrogel matrix has microtextures or through-pores to improve tissue anchoring and uniformity of RONS release.

5. The plasma-activated hydrogel spacer according to claim 1, characterized in that, The initial content of the RONS satisfies the following: hydrogen peroxide is 10-1000 μM, and / or nitrite is 10-1000 μM.

6. The plasma-activated hydrogel spacer according to claim 1, characterized in that, The RONS release curves were fitted by the Higuchi model or the Fick diffusion model, and the effective concentration range was maintained for 48–168 hours at 37 °C.

7. The plasma-activated hydrogel spacer according to claim 1, characterized in that, The energy storage modulus G' is preferably 5–25 kPa, the compressive strength is ≥10 kPa, and the failure strain is ≥20%.

8. The plasma-activated hydrogel spacer according to claim 1, characterized in that, The spacer also includes 0.1-20 wt% of a medical imaging contrast agent to achieve image localization, wherein the contrast agent is selected from iodine contrast agent, barium sulfate or tantalum powder.

9. The plasma-activated hydrogel spacer according to claim 1, characterized in that, The spacer contains a hydrophilic, radiopaque filler and is visible under CT or fluoroscopic images without significantly affecting dose distribution.

10. The plasma-activated hydrogel spacer according to claim 1, characterized in that, The spacer is in the form of a sheet, wedge, or block, with a length of 1–5 cm and a thickness of 0.5–2 cm; or it is an injectable gel-forming form, compatible with 18–22G injection needles.

11. A method for preparing a plasma-activated hydrogel spacer, characterized in that, The solvent or hydrogel precursor solution is activated by plasma using dielectric barrier discharge or plasma jet at a power of 1–30 W for 1–20 min, and then RONS is introduced to obtain a plasma-activated hydrogel spacer, or the solution containing RONS is cross-linked with the hydrogel precursor to obtain a plasma-activated hydrogel spacer.

12. The method for preparing a plasma-activated hydrogel spacer according to claim 11, characterized in that, The activating gas is argon, or argon-oxygen, wherein the volume percentage of oxygen is 0.1%-5%, or helium or air, the flow rate of the activating gas is 1-15 L / min, and the activation time is 0.5-5 min / 10 mL.

13. The method for preparing a plasma-activated hydrogel spacer according to claim 11, characterized in that, The crosslinking is photocuring and / or ionic crosslinking, wherein photocuring is performed by irradiation with a 365–405 nm light source for 10–600 s, and the photoinitiator is Irgacure 2959 or LAP, with an addition amount of 0.05–0.5 wt%; the ionic crosslinking is alginate-Ca2+ ionic crosslinking, and treatment with 10–100 mM CaCl2 solution for 1–10 min.

14. The method for preparing a plasma-activated hydrogel spacer according to claim 11, characterized in that, Add 0.1–20 wt% developer during the plasma-activated hydrogel spacer molding stage.

15. An application of a plasma-activated hydrogel spacer, characterized in that, Use of the plasma-activated hydrogel spacer of any one of claims 1 to 14 in brachytherapy products for tumors.