Near-infrared light response in-situ gelling and photo-thermal-photodynamic synergistic gel delivery system as well as preparation method and application thereof

Abstract

The invention relates to a near-infrared light response in-situ gelling and synergistic photo-thermal-photodynamic gel delivery system and a preparation method and application thereof, a mesoporous silicon coated up-conversion nano-carrier and an efficient photosensitizer are compounded to form a photo-response core unit, and then the photo-response core unit is intelligently integrated with photo-curing hydrogel to form the near-infrared light response in-situ gelling and synergistic photo-thermal-photodynamic gel delivery system. The general problem of aggregation and quenching of photosensitive molecules is relieved by utilizing the unique space confinement effect of the mesoporous structure, the ICG photo-thermal efficiency and photodynamic performance are enhanced, under precise excitation of a near-infrared light source, the system can activate a photo-crosslinking reaction through an up-conversion luminescence process, in-situ conversion from a liquid eye drop preparation to a stable gel state is achieved, and the stability of the eye drop preparation is improved. A lasting drug reservoir is formed on the surface of the cornea; synchronously excited photodynamic and photo-thermal dual-mode treatment generates a remarkable synergistic antibacterial effect, and shows an excellent removal capability on pathogens including highly drug-resistant bacteria; meanwhile, an ideal microenvironment is created for tissue repair through high biocompatibility and a stable mechanical matrix, and integrity recovery of cornea structures and functions is promoted.

Description

Technical Field

[0001] This invention relates to the field of ophthalmic drug delivery systems and anti-infective biomaterials, specifically to a near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system, its preparation method, and its applications. Background Technology

[0002] Bacterial keratitis, a major cause of blindness, faces three core challenges in its clinical diagnosis and treatment: First, traditional eye drops suffer from insufficient drug retention time on the ocular surface due to the physiological barrier characteristics of the eye, resulting in significantly limited bioavailability. This forces clinicians to adopt a high-concentration, high-frequency dosing regimen, which raises risks of ocular surface irritation and patient compliance issues. Second, pathogen identification relies on laboratory culture, and its insufficient detection cycle and sensitivity can delay the timing of precise treatment. Third, current treatment strategies combining antibiotics and corticosteroids have clinical limitations such as the development of drug resistance, delayed corneal repair, and the risk of secondary infections.

[0003] Traditional treatment primarily uses topical antibiotic eye drops, but the rapid spread of drug-resistant strains has significantly reduced efficacy. Clinically, this has forced the adoption of high-frequency, multi-drug regimens, which increases the risk of corneal epithelial toxicity (e.g., aminoglycosides) and conjunctival goblet cell damage, and also leads to decreased patient compliance due to excessively high dosing frequency. More seriously, when the corneal ulcer depth exceeds one-third of the corneal thickness, eye drops struggle to penetrate the dense fibrous layer, resulting in drug concentrations at the lesion site below 1% of the minimum inhibitory concentration (MIC), failing to eradicate pathogens within the stroma. Furthermore, the lack of mechanisms to promote collagen remodeling and epithelial regeneration prolongs the average healing time to 4–6 weeks, with a scar formation rate as high as 60%. Traditional "dispersion" systems face the following problems when applied to the eye: tear flushing (15% renewal per minute), blink reflex (once every 3–5 seconds), and nasolacrimal duct drainage can remove >95% of the drug within 5 minutes, leaving less than 15 minutes of retention time on the corneal surface, resulting in bioavailability of <1%.

[0004] Based on existing literature, current technologies face three major bottlenecks: 1. While simple ICG encapsulation alleviates the ACQ effect, it lacks the ability to actively anchor deep ulcer lesions, making it difficult for nanoparticles to diffuse within the matrix layer and form an effective therapeutic concentration gradient; 2. Although 808 nm excitation increases penetration depth, existing systems cannot utilize NIR light to induce in-situ cross-linking, resulting in the loss of therapeutic particles with tear fluid and the inability to achieve spatiotemporally controllable "lesion locking"; 3. Traditional eye drops only fulfill the function of drug delivery and cannot provide the moist microenvironment and extracellular matrix (ECM) scaffold required for corneal repair, leading to noticeable scarring after ulcer healing.

[0005] However, current treatments for bacterial keratitis still have the following technical limitations: 1. Insufficient drug retention: Traditional ophthalmic drops are constrained by the dynamic ocular surface environment, making it difficult to maintain a sustained and effective therapeutic concentration. The high-frequency dosing mode aggravates local side effects, resulting in poor patient compliance and limited efficacy.

[0006] 2. Intervention failure in deep lesions: Due to limitations in the penetration ability of light sources and the characteristics of tissue barriers, existing treatment systems cannot penetrate deep lesions.

[0007] 3. Conflict between drug resistance and drug toxicity: High-dose antibacterial regimens are often accompanied by significant cytotoxicity, while low-dose drugs face the risk of pathogen resistance.

[0008] 4. Decline in photosensitizer function and poor stability: Photosensitive molecules dissipate energy due to aggregation effect, resulting in nonlinear decay of therapeutic efficacy over time.

[0009] 5. Lack of means to promote repair after infection control: Currently, antibacterial drugs only focus on infection control, and there is a lack of means to repair corneal ulcers after infection control. Summary of the Invention

[0010] To address the aforementioned technical deficiencies in existing technologies, this invention provides a near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system, along with its preparation method and applications. By optimizing the stability of photosensitizers through mesoporous carriers and improving light energy utilization efficiency, and combining the optical properties of upconversion materials with the intelligent responsive behavior of bio-hydrogels, this invention achieves synchronized functional integration of sustained drug release and long-term retention under single-wavelength near-infrared light source excitation, photodynamic-photothermal synergistic antibacterial activity, and tissue microenvironment regulation. Ultimately, this forms a simple, low-frequency treatment regimen, providing a new technical pathway for improving the treatment efficacy of bacterial keratitis.

[0011] The technical solution adopted in this invention is: a near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system. The gel delivery system consists of a photoresponsive core unit composed of an upconversion nanocarrier coated with mesoporous silica loaded with a photosensitizer, and a collagen microenvironment similar to the corneal matrix provided by a phenyl-2,4,6-trimethylbenzoyl lithium phosphite (LAP) mediated gelMA hydrogel.

[0012] The mesoporous silica-coated upconversion nanocarrier is UCNPs@mSiO2 formed by coating upconversion nanoparticles UCNPs with Nd³⁺-doped NaYF4:Yb³⁺,Tm³⁺ cores with mesoporous silica mSiO2.

[0013] The aforementioned photoresponse core unit is UCNPs@mSiO2 constructed by loading the photosensitizer ICG to form UCNPs@mSiO2-ICG.

[0014] A method for preparing a near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system includes the following steps: (1) Synthesis of nanocrystals: YCl3, YbCl3 and ErCl3 were mixed with oleic acid and 1-octadecene. The mixed solution was heated to form a uniform transparent solution and then cooled to room temperature. Subsequently, a methanol solution containing NaOH and NH4F was slowly added to the flask and stirred continuously. The methanol was removed by slowly raising the temperature and degassing at 100°C. Then, the temperature was rapidly raised to 300°C under argon protection and kept constant. After the reaction was completed, the product nanocrystals were naturally cooled. The nanocrystals were precipitated with ethanol and washed three times with an ethanol / water mixture. (2) Aqueous phase transfer of nanocrystals: Take the above-mentioned nanocrystals and mix them with cyclohexane solution, then mix them with CTAB and water. Stir the mixture vigorously at room temperature to evaporate and remove the cyclohexane solvent, and finally obtain a transparent and clear aqueous solution of nanocrystals. (3) Mesoporous silica coating: Take an aqueous solution of CTAB-stabilized nanocrystals and add it to a mixture of water, ethanol and NaOH solution. Heat the mixture with stirring and slowly add tetraethyl orthosilicate (TEOS) to carry out the reaction. After the addition is complete, continue stirring to carry out the reaction. After the reaction is complete, collect the obtained nanoparticles by centrifugation and wash them with ethanol. (4) Removal of surfactant: The surfactant CTAB used in the coating process was removed by ion exchange. The nanoparticles obtained in step 3 were dispersed in an ethanol solution containing NH4NO3 and kept at 60 °C for 2 hours. After the treatment, the nanoparticles were finally dispersed in ethanol for storage. (5) Loading ICG: Take the ethanol dispersion obtained in step 4 and mix it with the ICG solution. Centrifuge the mixture and wash the precipitate with deionized water to remove unbound ICG, and obtain the UCNI nanocomposite, which is dispersed and stored in deionized water. (6) Preparation of nanocomposite gel and integration of photosensitizer: Take the UCNI aqueous dispersion obtained in step 5, add GelMA, and stir continuously under light-protected conditions until completely dissolved; then add LAP photoinitiator solution to a final concentration of 0.1% w / v to finally obtain GUCNI nanocomposite gel.

[0015] The concentration of the ethanol dispersion in step (5) is 2 mg mL⁻¹.

[0016] In step (5), the concentration of the ICG solution is 20 mg mL⁻¹.

[0017] Application of a near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system in the preparation of drugs for treating bacterial keratitis.

[0018] The medication mentioned for treating bacterial keratitis is a hydrogel eye drop.

[0019] The hydrogel eye drops undergo an in-situ transformation from a liquid eye drop formulation to a stable gel state under near-infrared light source excitation.

[0020] The near-infrared light source is an 808 nm laser with a power of 0.8 W / cm².

[0021] The beneficial effects of this invention are as follows: a near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system, its preparation method, and its application. This system combines a mesoporous silica-coated upconversion nanocarrier with a highly efficient photosensitizer to form a photoresponsive core unit, which is then intelligently integrated with a photocurable hydrogel. Utilizing the unique spatial confinement effect of the mesoporous structure, it alleviates the common problem of photosensitive molecule aggregation and quenching, enhancing the ICG photothermal efficiency and photodynamic performance. Under precise excitation by a near-infrared light source, the system can activate a photocrosslinking reaction through an upconversion luminescence process, achieving an in-situ transformation of the liquid eye drop formulation into a stable gel state, forming a long-lasting drug reservoir on the corneal surface. Simultaneously, the synchronized photodynamic and photothermal dual-mode treatment produces a significant synergistic antibacterial effect, exhibiting excellent clearance capabilities against pathogens, including highly drug-resistant bacteria. At the same time, the highly biocompatible and stable mechanical matrix creates an ideal microenvironment for tissue repair, promoting the restoration of the integrity of corneal structure and function. This technology integrates "precise light control," "long-lasting retention," and "synergistic bactericidal-repair" functions, making it suitable for the efficient treatment of clinically refractory corneal infections. Attached Figure Description

[0022] Figure 1 This diagram illustrates the synthesis of GelMA / UCNPs@mSiO2-ICG (GUCNI) nanocomposite hydrogel and its application in NIR-triggered in-situ gelation, photodynamic therapy, and photothermal therapy for the treatment of refractory keratitis.

[0023] Figure 2 A) TEM image and elemental spectrum of UCNPs@mSiO2; B) TEM image and elemental spectrum of UCNI.

[0024] Figure 3 Typical photographs of Staphylococcus aureus and Escherichia coli agar plates after various in vitro treatments, showing the sol-gel transition of GelMA, GUCN (GelMA / UCNPs@mSiO2), and GUCNI (GelMA / UCNPs@mSiO2-ICG) under 808 nm NIR irradiation.

[0025] Figure 4A. Infrared thermograph of the photothermal effect of GUCNI hydrogel; B. Photothermal curves of GUCNI with different concentrations after 808 nm light irradiation for different times; C. Photothermal curves of GUCNI after 808 nm light irradiation with different light powers for different times; D. Photothermal cycle diagram of GUCNI.

[0026] Figure 5 These are typical photographs of Staphylococcus aureus and Escherichia coli on agar plates after various in vitro treatments.

[0027] Figure 6 A. CCK-8 statistical graph of human corneal epithelial cells (HCECs) after different treatments; B. Fluorescence staining of live / dead cells of HCECs after different treatments.

[0028] Figure 7 This diagram illustrates the establishment of a model and treatment plan for refractory keratitis.

[0029] Figure 8 Images of ocular surface fluorescence in healthy mice treated with TOB, GUCN, and GUCN+NIR.

[0030] Figure 9 A. Slit-lamp images of different treatment groups; B. Line graphs of clinical scores of different treatment groups.

[0031] Figure 10 A photograph of bacterial culture on a corneal tissue agar plate.

[0032] Figure 11 Immunofluorescence staining images of MMP9, IL-1β and IL-6 in the cornea 5 days after different treatments. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] A multifunctional nanocomposite gel system based on near-infrared light response is presented. This gel system comprises a photosensitizer-loaded upconversion nanocarrier coated with mesoporous silica as the core photoresponsive unit. The mesoporous spatial confinement effect significantly inhibits the aggregation and quenching of photosensitizer molecules, simultaneously enhancing photothermal conversion efficiency and reactive oxygen species generation capacity. This unit is combined with a photocurable gelatin-methacrylamide hydrogel matrix and a photoinitiator, achieving in-situ cross-linking under near-infrared light triggering to form a stable network with mechanical properties adapted to corneal tissue. This system innovatively integrates three functions: achieving long-term drug retention on the ocular surface through gel curing; efficiently clearing drug-resistant pathogens through photothermal-photodynamic dual-mode synergy; and promoting corneal tissue regeneration and functional reconstruction by leveraging the bio-three-dimensional network structure of the hydrogel.

[0035] Reagent source and use: Indocyanine green (ICG) and lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) were purchased from Shanghai Aladdin Biotechnology Co., Ltd. GelMA (DS60) was purchased from Wenzhou Shuhe Biotechnology Co., Ltd. All other chemical reagents were purchased from Sigma-Aldrich Biotechnology Co., Ltd., specifically including: yttrium chloride hexahydrate (YCl3·6H2O, 99.99%), ytterbium chloride hexahydrate (YbCl3·6H2O, 99.99%), erbium chloride hexahydrate (ErCl3·6H2O, 99.99%), oleic acid (90%, industrial grade), octadecene (90%, industrial grade), tetraethyl orthosilicate (TES, >99%), cetyltrimethylammonium bromide (CTAB, >99%), ammonium nitrate (NH4NO3, ≥99.0%), sodium hydroxide (NaOH, reagent grade, ≥98%), and copper(II) sulfate pentahydrate (CuSO4·5H2O, ...). ≥98.5%) and 3-Aminopropyltriethoxysilane (APS).

[0036] Experimental steps: 1. Nanocrystal Synthesis: First, YCl3 (0.8 mmol), YbCl3 (0.18 mmol), and ErCl3 (0.02 mmol) were added to a 50 mL three-necked flask along with oleic acid (OA, 6 mL) and 1-octadecene (ODE, 15 mL). The mixture was heated to 160°C to form a homogeneous, transparent solution, and then cooled to room temperature. Subsequently, 10 mL of methanol solution containing NaOH (2.5 mmol) and NH4F (4 mmol) was slowly added to the flask, and the mixture was stirred continuously for 30 minutes. Afterward, the methanol was removed by slowly increasing the temperature, and the mixture was degassed at 100°C for 10 minutes. Then, under argon protection, the temperature was rapidly increased to 300°C and maintained at this temperature for 1 hour. After the reaction was complete, the mixture was allowed to cool naturally. The resulting nanocrystals were precipitated with ethanol and washed three times with an ethanol / water (1:1 v / v) mixture.

[0037] 2. Aqueous phase transfer of nanocrystals: Take 2 mL of a solution containing the above-mentioned nanocrystals and cyclohexane (concentration 5 mg / mL), then mix with 0.1 g CTAB and 20 mL of water. Stir the mixture vigorously at room temperature to evaporate and remove the cyclohexane solvent, finally obtaining a clear aqueous solution with a nanocrystal concentration of approximately 0.5 mg / mL.

[0038] 3. Mesoporous silica coating: Take 10 mL of the above-mentioned CTAB-stabilized nanocrystal aqueous solution and add it to a mixture consisting of 20 mL of water, 3 mL of ethanol, and 150 μL of 2 M NaOH solution. Heat the mixture to 70 °C with stirring. After reaching this temperature, slowly add 150 μL of tetraethyl orthosilicate (TEOS) to initiate the reaction. After the addition is complete, continue stirring at 70 °C for 10 minutes. After the reaction is complete, collect the obtained nanoparticles by centrifugation and wash them three times with ethanol.

[0039] 4. Removal of Surfactant: To avoid dissolving the nanoparticles under acidic conditions, an ion exchange method was used to remove the surfactant CTAB used in the coating process. The nanoparticles obtained in step 3 were dispersed in 50 mL of an ethanol solution containing 0.3 g of NH4NO3 and kept at 60 °C for 2 hours. After treatment, the nanoparticles were finally dispersed in ethanol for storage.

[0040] 5. Loading ICG: Take 1 mL of the ethanol dispersion obtained in step 4 (concentration 2 mg mL⁻¹) and mix it with 1 mL of ICG solution (concentration 20 mg mL⁻¹). Centrifuge the mixture (12000 rpm, 5 min) and wash the precipitate 3 times with deionized (DI) water to remove unbound ICG. The UCNI nanocomposite is finally dispersed and stored in deionized water.

[0041] 6. Preparation of nanocomposite gel and integration of photosensitizer: Take 5 mL of the UCNI aqueous dispersion obtained in step 5, add GelMA (DS60), and stir continuously at 37°C in the dark until completely dissolved; then add LAP photoinitiator solution to a final concentration of 0.1% w / v to finally obtain GUCNI nanocomposite gel (stored in the dark).

[0042] Example 1 like Figure 1 As shown, the synthesis pathway and therapeutic mechanism of GUCNI nanocomposite materials are fully demonstrated: Upconversion nanoparticles (UCNPs) with NaYF4:Yb³⁺,Tm³⁺ (Nd³⁺ doped) as the core are coated with mesoporous silica (mSiO2) to form a drug-carrying platform, and UCNPs@mSiO2-ICG is constructed by loading the photosensitizer ICG; After the nanoparticles are combined with the photocurable hydrogel GelMA / LAP, a dual response is triggered by 808nm near-infrared light, including: upconversion luminescence (UCL) activates LAP to induce in-situ gelation and prolong drug retention; and ICG is simultaneously excited to release singlet oxygen (¹O2) to achieve photothermal / photodynamic synergistic bactericidal effect (PTT / PDT); Finally, by downregulating inflammatory factors (MMP-9 / IL-1β / IL-6), promoting corneal cell proliferation and migration and tissue regeneration, an integrated therapeutic closed loop from pathogen clearance to microenvironment reconstruction is completed.

[0043] Example 2 like Figure 2 TEM images and elemental maps show that the elemental mapping results indicate that Y and F elements are located within the UCNP core, while Si elements form a uniform outer shell. The S signal is undetectable in UCNPs@mSiO2 but co-located with Si in UCNI, confirming the ICG loading.

[0044] Example 3 like Figure 3 As shown, the results indicate that GelMA could not gel under 808 nm NIR irradiation, while GUCN and GUCNI hydrogels achieved rapid and complete photocuring within 1 minute, enabling rapid gelation after local ocular administration to avoid rapid removal by blinking or tear drainage, thereby reducing the frequency of administration.

[0045] Example 4 like Figure 4 As shown, the results indicate that GUCNI exhibits excellent photothermal effects under 808 nm illumination, and these effects are positively correlated with the light power at 808 nm and the concentration of GUCNI. Furthermore, GUCNI demonstrates excellent photothermal stability and can maintain good photothermal efficiency after multiple photothermal cycles.

[0046] Example 5 like Figure 5 As shown, no significant reduction in Staphylococcus aureus and Escherichia coli was observed in the control group, control group + NIR, GUCN, GUCN + NIR, or GUCNI group. In contrast, almost all bacteria died after GUCNI + NIR treatment. These results indicate that under NIR irradiation, GUCNI synergistically binds to PTT and PDT, exerting a potent bactericidal effect against both Gram-positive and Gram-negative pathogens.

[0047] Example 6 like Figure 6 As shown, the results indicated that after 30 minutes of co-incubation with UCNI, the activity of HCECs remained largely unchanged under dark conditions. After 30 minutes of irradiation with 808 nm near-infrared light, the activity of HCECs in the high-concentration UCNI group decreased slightly, but remained above 80%. Under dark conditions, after 72 hours of co-incubation with UCNI, HCECs exhibited continuous proliferation and minimal cell death, validating the excellent biocompatibility of UCNPs@mSiO2, GUCN, UCNI, and GUCNI under dark conditions.

[0048] Example 7 like Figure 7 As shown, female BALB / c mice (weighing 22-25 g, aged 6-8 weeks, n=5 per group) were used to establish the model. After mechanically scraping the corneal epithelium, the mice were inoculated with a methicillin-resistant Staphylococcus aureus (MRSA) suspension (100 μL, concentration 1×10⁻⁶). 8 Infection was induced by CFU / mL. After infection, patients were evenly grouped according to their clinical scores on Day 0: Control group: PBS eye drops (5 μL / time, 3 times / day); Positive control group: Tobramycin eye drops (5 μL / time, 3 times / day); GUCNI group: GUCNI preparation (5 μL / time, 1 time / day, no near-infrared light irradiation); GUCNI+NIR group: GUCNI preparation (5 μL / time, 1 time / day) combined with 808 nm near-infrared light irradiation (power density 0.8 W / cm², 5 minutes / time); GUCNI+NIR group: GUCNI preparation (5 μL / time, 1 time / day) combined with NIR irradiation with the same parameters.

[0049] Each group received treatment for 5 days, and the evaluation indicators included: 1. Clinical scoring (0-16 point composite system): corneal opacity (0-4 points), neovascularization coverage (0-4 points), ulcer area (0-8 points); 2. Quantitative bacterial load: On day 5, corneal tissue homogenate was collected and incubated on LB agar plates at 37°C for 24 hours for bacterial count. 3. Analysis of inflammatory factors: Immunofluorescence staining was used to detect the expression of IL-1β, MMP-9 and IL-6 (antibody dilution ratio 1:50-1:100).

[0050] Example 8 like Figure 8 As shown, the results indicated that the TOB group became completely undetectable at 40 minutes, indicating a short ocular surface retention time. The GUCN group maintained fluorescence signals for over 55 minutes, while the GUCN+NIR group exhibited sustained strong fluorescence at 60 minutes, indicating that NIR-induced gelation significantly enhanced retention. Example 9 like Figure 9 As shown, the results indicated that the UCNI+NIR group achieved near-complete regression of corneal lesions on day 5 (clinical score 1.2±0.2), and corneal transparency was significantly better than other groups (such as the TOB group score 7.2±0.5), confirming the excellent effect of synergistic treatment on tissue repair.

[0051] Example 10 like Figure 10 As shown, the results indicated that colony formation in the GUCNI+NIR group was close to zero, validating its effectiveness in killing keratitis pathogens. Among the other groups, only TOB showed a significant reduction in bacteria compared to PBS, demonstrating that GUCNI+NIR is a better treatment option than the traditional antibiotic eye drops tobramycin.

[0052] Example 11 like Figure 11 As shown, the results revealed significant downregulation of MMP9, IL-1β, and IL-6 in the GUCNI+NIR group, confirming its ability to reduce inflammatory infiltration by eliminating pathogens.

[0053] in conclusion 1. This invention integrates anti-infection, anti-inflammatory and tissue repair functions into a synergistic system, and simultaneously activates three composite treatment mechanisms through a single 808nm light trigger.

[0054] 2. Hydrogels anchor the drug at the site of injury, providing continuous photodynamic / photothermal therapy and maintaining a stable therapeutic concentration, effectively addressing the core pain point of short duration of action of traditional formulations.

[0055] 3. It integrates a dual-mode antibacterial pathway that combines physical membrane disruption and chemical oxidative damage, circumventing traditional antibiotic resistance mechanisms and providing a novel solution for drug-resistant infections.

[0056] 4. Based on conventional near-infrared laser 808nm, it realizes instant photocuring combined with photothermal / photodynamic therapy, without the need for complex instrument support, which greatly simplifies the treatment process and significantly reduces the technical application threshold and execution cost.

[0057] Please note to those skilled in the art: Although the present invention has been explained through the specific embodiments described above, the inventive concept of the present invention is not limited thereto. Any improvements or variations based on the inventive concept fall within the protection scope of this patent.

[0058] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments and experimental examples. Any technical solution following the concept of the present invention is included within the scope of protection of the present invention. It should be emphasized that for those skilled in the art, any modifications or equivalent substitutions without departing from the spirit and scope of the present invention should be considered as part of the scope of protection of the present invention.

Claims

1. A near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system, characterized in that, The gel delivery system consists of a photosensitizer loaded on an upconversion nanocarrier coated with mesoporous silica as the photoresponsive core unit and a collagen microenvironment similar to the corneal matrix provided by a phenyl-2,4,6-trimethylbenzoyl lithium phosphite (LAP) mediated gelMA hydrogel.

2. The near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system according to claim 1, characterized in that, The mesoporous silica-coated upconversion nanocarrier is UCNPs@mSiO2 formed by coating upconversion nanoparticles UCNPs with Nd³⁺-doped NaYF4:Yb³⁺,Tm³⁺ cores with mesoporous silica mSiO2.

3. The ROS-responsive zwitterionic nanomicelle delivery system according to claim 2, characterized in that, The aforementioned photoresponsive core unit is UCNPs@mSiO2 constructed by loading the photosensitizer ICG to form UCNPs@mSiO2-ICG.

4. A method for preparing the near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system as described in claim 1, characterized in that, Includes the following steps: (1) Synthesis of nanocrystals: YCl3, YbCl3 and ErCl3 were mixed with oleic acid and 1-octadecene. The mixed solution was heated to form a uniform transparent solution and then cooled to room temperature. Subsequently, a methanol solution containing NaOH and NH4F was slowly added to the flask and stirred continuously. The methanol was removed by slowly raising the temperature and degassing at 100°C. Then, the temperature was rapidly raised to 300°C under argon protection and kept constant. After the reaction was completed, the product nanocrystals were naturally cooled. The nanocrystals were precipitated with ethanol and washed three times with an ethanol / water mixture. (2) Aqueous phase transfer of nanocrystals: Take the above-mentioned nanocrystals and mix them with cyclohexane solution, then mix them with CTAB and water. Stir the mixture vigorously at room temperature to evaporate and remove the cyclohexane solvent, and finally obtain a transparent and clear aqueous solution of nanocrystals. (3) Mesoporous silica coating: Take an aqueous solution of CTAB-stabilized nanocrystals and add it to a mixture of water, ethanol and NaOH solution. Heat the mixture with stirring and slowly add tetraethyl orthosilicate (TEOS) to carry out the reaction. After the addition is complete, continue stirring to carry out the reaction. After the reaction is complete, collect the obtained nanoparticles by centrifugation and wash them with ethanol. (4) Removal of surfactant: The surfactant CTAB used in the coating process was removed by ion exchange. The nanoparticles obtained in step 3 were dispersed in an ethanol solution containing NH4NO3 and kept at 60 °C for 2 hours. After the treatment, the nanoparticles were finally dispersed in ethanol for storage. (5) Loading ICG: Take the ethanol dispersion obtained in step 4 and mix it with the ICG solution. Centrifuge the mixture and wash the precipitate with deionized water to remove unbound ICG, and obtain the UCNI nanocomposite, which is dispersed and stored in deionized water. (6) Preparation of nanocomposite gel and integration of photosensitizer: Take the UCNI aqueous dispersion obtained in step 5, add GelMA, and stir continuously under light-protected conditions until completely dissolved; then add LAP photoinitiator solution to a final concentration of 0.1% w / v to finally obtain GUCNI nanocomposite gel.

5. The preparation method according to claim 4, characterized in that, The concentration of the ethanol dispersion in step (5) is 2 mg mL⁻¹.

6. The preparation method according to claim 4, characterized in that, In step (5), the concentration of the ICG solution is 20 mg mL⁻¹.

7. The application of the near-infrared light-responsive in-situ gelation and synergistic photothermal-photodynamic gel delivery system of claim 1 in the preparation of a drug for treating bacterial keratitis.

8. The application according to claim 7, characterized in that, The medication mentioned for treating bacterial keratitis is a hydrogel eye drop.

9. The application according to claim 8, characterized in that, The hydrogel eye drops undergo an in-situ transformation from a liquid eye drop formulation to a stable gel state under near-infrared light source excitation.

10. The application according to claim 8, characterized in that, The near-infrared light source is an 808 nm laser with a power of 0.8 W / cm².

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