A six-membered bicyclic aliphatic carbonate monomer containing a sulfide bond and a preparation method and application thereof

Abstract

This invention discloses a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond, its preparation method, and its application. The molecular structure of the six-membered bicyclic aliphatic carbonate monomer containing a thioether bond is shown in the following formula (1): (1). The carbonate monomer and its polymer provided by this invention have excellent response characteristics to reactive oxygen species. Under high concentrations of reactive oxygen species, the hydrophobic thioether is gradually oxidized to a more hydrophilic sulfoxide or sulfone structure, thereby significantly changing the hydrophilicity and hydrophobicity of the material. The trithioether bond also has strong electron donor characteristics and can react with a variety of reactive oxygen species to achieve the capture and consumption of reactive oxygen species, thus having antioxidant capacity. The amphiphilic polycarbonate obtained by polymerizing this carbonate monomer can self-assemble into nanoparticles in aqueous solution. Its hydrophobic core can load hydrophobic drugs, and the hydrophilic shell provides good colloidal stability, enabling intelligent drug release in pathological oxidative environments.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer compound technology, specifically relating to a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond, its preparation method, and its application. Background Technology

[0002] In recent years, pathological conditions such as tumors, cardiovascular and cerebrovascular diseases, and inflammation have been generally accompanied by a continuous increase in reactive oxygen species (ROS) levels, providing an important opportunity for the development of functional polymer materials. ROS include hydrogen peroxide (H2O2), hydroxyl radicals (·OH), and superoxide anions (O2). - Highly reactive molecules such as α, β, and γ are involved in cell signal transduction and immune defense under normal physiological conditions, and maintain dynamic homeostasis through the antioxidant system. However, in pathological environments such as tumors, cardiovascular and cerebrovascular diseases, inflammation, and autoimmune diseases, abnormal accumulation of ROS levels can easily cause irreversible damage to proteins, lipids, and nucleic acids, thereby inducing apoptosis or necrosis.

[0003] The microenvironment characterized by oxidative stress not only drives disease progression but also provides a specific triggering mechanism for drug delivery systems. Therefore, constructing intelligent carriers capable of sensing and responding to ROS has become a research hotspot in the field of precision medicine. Such carriers can achieve selective drug release at the lesion site, helping to reduce systemic toxicity and improve treatment efficiency.

[0004] Among various candidate materials, polycarbonate has attracted much attention due to the high designability of its molecular structure. Compared with traditional polyesters such as polylactic acid (PLA) and polycaprolactone (PCL), polycarbonate can achieve precise control of degradation rate, hydrophilicity / hydrophobicity, and responsive groups through molecular modification of cyclic carbonate monomers. At the same time, its degradation products are mostly neutral or weakly polar small molecules, which have less irritation to surrounding tissues and better meet the requirements of pathological tissues for material mildness. These characteristics make polycarbonate an ideal candidate for constructing ROS-responsive drug delivery platforms. Nevertheless, existing ROS-responsive monomers based on cyclic carbonates still have certain shortcomings: (1) single function, most materials only rely on ROS-induced degradation and lack the ability to simultaneously remove ROS; (2) limited response sensitivity, insufficient triggering efficiency under low concentration ROS conditions, making it difficult to achieve early intervention; (3) limited overall performance, some monomers perform poorly in terms of biocompatibility, polymerization activity, or structural stability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a six-membered bicyclic aliphatic carbonate monomer containing thioether bonds, its preparation method and application. This carbonate monomer has the properties of rapid response to ROS, triggering drug release and scavenging excess ROS. After ring-opening polymerization, a functional polycarbonate with excellent biocompatibility and biodegradability can be obtained, which is expected to show broad prospects in the fields of drug delivery, tissue repair and treatment of cardiovascular and cerebrovascular diseases.

[0006] The first aspect of this invention is to provide a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond, the molecular structure of which is shown in the following formula (1): (1).

[0007] The second aspect of this invention provides a method for preparing the above-mentioned six-membered bicyclic aliphatic carbonate monomer containing a thioether bond, the specific steps of which are as follows: 1) Synthesis of a dihydroxy monomer containing a trisulfide bond (TESPBDHMP): 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester is reacted with dimercaptoethyl sulfide in a mercapto-olefin "click" chemical reaction, and then purified to obtain a dihydroxy monomer containing a trisulfide bond; 2) Synthesis of a six-membered bicyclic aliphatic carbonate monomer containing thioether bonds (TESPBMTC): The dihydroxy monomer containing trithioether bonds obtained in step 1) is subjected to a cyclization reaction with ethyl chloroformate, and then purified to obtain a six-membered bicyclic aliphatic carbonate monomer containing thioether bonds.

[0008] According to the above scheme, the molar ratio of 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester to dimercaptoethyl sulfide in step 1) is 2-4:1.

[0009] According to the above scheme, the conditions for the "click" chemical reaction of the mercapto-ene in step 1) are: under an inert atmosphere, using azobisisobutyronitrile as an initiator, the reaction is carried out at 60-80℃ for 12-60h.

[0010] According to the above scheme, in step 1), 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester and dimercaptoethyl sulfide undergo a mercapto-olefin "click" chemical reaction. The specific steps are as follows: 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester and dimercaptoethyl sulfide are dissolved in anhydrous DMF, and then azobisisobutyronitrile (AIBN) is added. The reaction system is subjected to liquid nitrogen freezing-thawing cycle to remove residual oxygen in the system, and then the reaction is carried out. After the reaction is completed, the reaction solution is concentrated under reduced pressure. The crude product is purified by silica gel column chromatography to obtain the product.

[0011] According to the above scheme, the mass-to-volume ratio of 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester to anhydrous DMF is 0.05-0.1 g / mL.

[0012] According to the above scheme, the molar ratio of 2,2-bis(hydroxymethyl)propionic acid-2-propylene ester to azobisisobutyronitrile is 2-4:1.

[0013] According to the above scheme, the molar ratio of the trisulfide-containing dihydroxy monomer to ethyl chloroformate in step 2) is 1:2-6.

[0014] According to the above scheme, the cyclization reaction conditions for step 2) are: under an inert atmosphere, triethylamine is used as an acid-binding agent, and the reaction is carried out at 10-30℃ for 4-12 hours.

[0015] According to the above scheme, the specific steps of step 2) of the cyclization reaction between the trisulfide-containing dihydroxy monomer and ethyl chloroformate are as follows: the trisulfide-containing dihydroxy monomer is dissolved in anhydrous tetrahydrofuran (THF), ethyl chloroformate is added to the resulting solution under ice bath conditions, and then a tetrahydrofuran solution of triethylamine is slowly added dropwise. After the addition is completed, the cyclization reaction is carried out. After the reaction is completed, the generated triethylamine hydrochloride precipitate is removed by filtration, the filtrate is concentrated under reduced pressure, and the crude product is purified by silica gel column chromatography to obtain the product.

[0016] According to the above scheme, the molar volume ratio of the trisulfide-containing dihydroxy monomer to anhydrous tetrahydrofuran is 0.04-0.083 mmol / mL.

[0017] According to the above scheme, the concentration of the triethylamine in the tetrahydrofuran solution is 1.6-3.3 mmol / mL, wherein the molar ratio of triethylamine to the trisulfide bonded dihydroxy monomer is 4-8:1.

[0018] The synthetic route of this invention is as follows:

[0019] A third aspect of this invention is to provide the use of the aforementioned six-membered bicyclic aliphatic carbonate monomer containing a thioether bond in the preparation of a drug delivery carrier for treating oxidative stress diseases. Oxidative stress diseases include chronic inflammation, autoimmune diseases, cardiovascular and cerebrovascular diseases, malignant tumors, etc.

[0020] According to the above scheme, the specific application method is as follows: the six-membered bicyclic aliphatic carbonate monomer containing thioether bonds is polymerized, or copolymerized with other polymerizable monomers and macromolecular monomers (ε-caprolactone, lactic acid, polyethylene glycol monomethyl ether, etc.) to form block polymers or random copolymers, which are used as drug carriers.

[0021] The six-membered bicyclic aliphatic carbonate monomer containing thioether bonds provided by this invention can undergo ring-opening polymerization under organic / metal catalysts to obtain a biodegradable polycarbonate with controllable molecular weight and narrow molecular weight distribution. This polycarbonate can self-assemble into nanoparticles with a particle size of 20-250 nm, which can be used for efficient encapsulation of hydrophobic anticancer or antioxidant drugs (such as paclitaxel, doxorubicin, and astaxanthin). The nanoparticles can avoid clearance by the reticuloendothelial system. After entering the cell, the trithioether bonds contained in the polymer can absorb reactive oxygen species and undergo an oxidation response under the action of high concentrations of reactive oxygen species in the cell, thereby releasing the encapsulated drug. In addition, the degradation rate of this polycarbonate can be controlled by the copolymer composition. The degradation products are CO2 and diols, which are non-cytotoxic. The degradation products can be excreted by the kidneys or absorbed by metabolism in vivo, without the risk of long-term accumulation.

[0022] The beneficial effects of this invention are as follows: 1. The six-membered bicyclic aliphatic carbonate monomer and its polymer containing thioether bonds provided by this invention have excellent response characteristics to reactive oxygen species (ROS). Under high concentrations of ROS, the hydrophobic thioether is oxidized to a more hydrophilic sulfoxide or sulfone structure, thereby significantly changing the hydrophilicity or hydrophobicity of the material. The trithioether bond also has strong electron donor characteristics and can react with various ROS species to capture and consume ROS, thus efficiently scavenging ROS and exhibiting strong antioxidant capacity. The amphiphilic polycarbonate obtained by polymerizing this carbonate monomer can self-assemble into nanoparticles in aqueous solution. Its hydrophobic core can load hydrophobic drugs, and its hydrophilic shell provides good colloidal stability, enabling intelligent drug release in pathological oxidative environments such as tumors, cardiovascular and cerebrovascular diseases, and autoimmune diseases where ROS is overexpressed. 2. The raw materials of this invention are widely available, structurally stable, and relatively inexpensive, which helps to reduce the overall preparation cost. The synthesis route is simple and the conditions are mild, requiring no high temperature or high pressure conditions, and the yield is high, showing good prospects for industrial application. Attached Figure Description

[0023] Figure 1 The hydrogen nuclear magnetic resonance spectrum of the TESPBDHMP prepared in Example 1 of this invention; Figure 2 The carbon NMR spectrum of the TESPBDHMP prepared in Example 1; Figure 3 The hydrogen nuclear magnetic resonance spectrum of the TESPBMTC prepared in Example 1; Figure 4 The carbon NMR spectrum of TESPBMTC prepared in Example 1; Figure 5 Comparison of 1H NMR spectra of TESPBDHMP prepared in Example 1 dispersed in D2O and D2O containing 1.0 wt% H2O2; Figure 6 mPEG-b-PTESPBMTC prepared in Example 2 10 The proton NMR spectrum; Figure 7 The 1H NMR spectrum of mPEG-bP(TESPBMTC-co-CL) prepared in Example 4; Figure 8 The particle size distribution diagram is shown for the polymer colloidal particles prepared in Example 5. Figure 9 This is a stability test chart of particle size and particle size distribution index of colloidal particles in the colloidal particle dispersion of Example 5 after standing for 7 days. Figure 10 TEM image of the polymer colloidal particles prepared in Example 5; Figure 11 Example 6: Polymer colloidal particle dispersions of different concentrations on ABTS· + A comparison chart of clearance rates; Figure 12 ABTS in Example 6 + The ultraviolet fluorescence spectra of the reaction solution obtained after mixing and reacting the working solution with polymer colloidal particle dispersions of different concentrations; Figure 13 This is a comparison chart of the scavenging rates of DPPH· by polymer colloidal particle dispersions of different concentrations in Example 6. Figure 14 The UV fluorescence spectra of the reaction solution obtained after mixing and reacting the DPPH working solution with polymer colloidal particle dispersions of different concentrations in Example 6 are shown. Figure 15 This is a comparison chart of the scavenging rates of ·OH by polymer colloidal particle dispersions of different concentrations in Example 6; Figure 16 The UV fluorescence spectra of the reaction solution obtained after mixing and reacting the OH reagent solution with polymer colloidal particle dispersions of different concentrations in Example 6 are shown. Figure 17 This is a comparison of the survival rates of OC-1 and L929 cells in polymer colloidal particle dispersions of different concentrations in Example 7; Figure 18 This is a comparison chart of the cumulative drug release efficiency of the drug-loaded polymer colloidal particles in Example 9 under different concentrations of H2O2 at different times. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] Example 1 A six-membered bicyclic aliphatic carbonate monomer containing a thioether bond is prepared as follows: 1) Synthesis of a trithioether-containing dihydroxy monomer (TESPBDHMP): 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester (3.48 g, 20 mmol) and dimercaptoethyl sulfide (1.54 g, 10 mmol) were dissolved in 50 mL of anhydrous DMF. AIBN (0.82 g, 10 mmol) was added to the resulting solution as a free radical initiator. The reaction system was subjected to three liquid nitrogen freeze-thaw cycles to remove residual oxygen. Subsequently, under nitrogen protection, the reaction system was placed in a 70 °C oil bath and stirred for 48 h. After the reaction was completed, the reaction solution was concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain a colorless viscous liquid product TESPBDHMP (3.74 g, yield 74.5%). 2) Synthesis of a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond (TESPBMTC): Under nitrogen protection, the trithioether bond dihydroxy monomer (2.51 g, 5 mmol) obtained in step 1) was dissolved in 100 mL of anhydrous THF, and the reaction system was cooled to 0 °C in an ice bath. Then, ethyl chloroformate (2.0 mL, 20 mmol) was added to the reaction system, and triethylamine (3.1 mL, 20 mmol) was dissolved in 10 mL of anhydrous THF to prepare a TEA solution, which was slowly added dropwise to the above reaction system over 1 h. After the addition was completed, the ice bath was removed, the reaction system was heated to room temperature, and the reaction was stirred overnight. After the reaction was completed, the triethylamine hydrochloride precipitate was removed by filtration, the filtrate was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography to obtain a colorless viscous liquid TESPBMTC (2.3 g, yield 83.0%).

[0026] like Figure 1 The image shows the hydrogen nuclear magnetic resonance spectrum of the TESPBDHMP prepared in this embodiment. Figure 2 This is the carbon NMR spectrum of TESPBDHMP.

[0027] Figure 3 The image shows the hydrogen nuclear magnetic resonance spectrum of the TESPBMTC prepared in this embodiment. Figure 4 This is the carbon NMR spectrum of TESPBMTC.

[0028] The TESPBDHMP prepared in this embodiment was dispersed in D2O (denoted as W / O H2O2) and D2O containing 1.0 wt% H2O2 (denoted as W / H2O2), respectively. 1 H NMR was used for detection and comparison, and the test results are as follows: Figure 5As shown in the comparison, it can be seen that when H2O2 is present in the system, the characteristic -CH2-S- proton signal (δ2.6ppm and 2.8ppm, peaks a and b) is weakened or even completely disappeared compared with W / O H2O2. At the same time, two new methylene resonance peaks (peaks a' and b') appear in δ3.1-3.2ppm, corresponding to the sulfoxide / sulfone structure generated by oxidation. The chemical shift peak c shifts slightly to the lower field from ~4.1ppm to ~4.2ppm, and peak c' appears.

[0029] Example 2 A polycarbonate block polymer containing trisulfide bonds, mPEG-b-PTESPBMTC 10 Its preparation method is as follows: In an ampoule that had been flame-dried, polyethylene glycol monomethyl ether (mPEG) (0.30 g, 0.06 mmol) was added. The ampoule was then vacuum-dried at 90 °C for 2 h to remove residual moisture. After cooling to room temperature, 0.33 g of the TESPBMTC monomer prepared in Example 1 (0.6 mmol) and 8.35 mg of the organic base catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) (0.06 mmol) were added sequentially under nitrogen protection. Then, 10 mL of anhydrous dichloromethane was added to the system, and the mixture was stirred at room temperature for 6 h. After the reaction was complete, the reaction solution was concentrated and then slowly added dropwise to ice-cold diethyl ether to allow the polymer to precipitate. The precipitate was collected by filtration and dried under vacuum to obtain a pale yellow solid, mPEG-b-PTESPBMTC. 10 The yield was 88.9%.

[0030] Figure 6 mPEG-b-PTESPBMTC prepared in this embodiment 10 The proton NMR spectrum.

[0031] After testing, the mPEG-b-PTESPBMTC prepared in this embodiment was found to be effective. 10 The number-average molecular weight is 1.05 × 10⁻⁶. 4 The molecular weight distribution index is 1.36.

[0032] Example 3 A polycarbonate block polymer containing trisulfide bonds, mPEG-b-PTESPBMTC 15 The preparation method is similar to that in Example 2, except that the amount of TESPBMTC monomer added is 0.9 mol and the molar ratio of mPEG to TESPBMTC monomer is 1:15.

[0033] After testing, the mPEG-b-PTESPBMTC prepared in this embodiment was found to be effective. 15 The number-average molecular weight is 1.33 × 10⁻⁶.4 The molecular weight distribution index is 1.17.

[0034] Example 4 A block copolymer mPEG-bP (TESPBMTC-co-CL) is prepared as follows: 0.2 g (0.04 mmol) of mPEG 5000 was placed in a reaction flask and dried under vacuum at 90 °C for 2 h to remove residual moisture. After cooling to room temperature, 0.22 g (0.4 mmol) of TESPBMTC monomer prepared in Example 1, 0.045 g (approximately 0.4 mmol) of ε-caprolactone, and 5.56 mg (0.04 mmol) of TBD were added sequentially under nitrogen protection. Then, 10 mL of anhydrous dichloromethane was added to the system, and the mixture was stirred at room temperature for 4 h. After the reaction was completed, the reaction solution was concentrated and then slowly added dropwise to ice-cold diethyl ether to allow the polymer to precipitate. The precipitate was collected by filtration and dried under vacuum to obtain 0.315 g of pale white solid mPEG-bP (TESPBMTC-co-CL), with a yield of 67.5%.

[0035] Figure 7 The image shows the 1H NMR spectrum of the mPEG-bP(TESPBMTC-co-CL) prepared in this embodiment.

[0036] The number-average molecular weight of the mPEG-bP(TESPBMTC-co-CL) prepared in this embodiment was tested and found to be 1.16 × 10⁻⁶. 4 The molecular weight distribution index is 1.32.

[0037] Example 5 A polymer colloidal particle is prepared by the following method: Weigh 4 mg of mPEG-b-PTESPBMTC prepared in Example 2 10 Dissolve in 100 μL of chloroform, then quickly add the resulting solution to 4 mL of distilled water under sonication, and continue sonicating until the oily droplets completely disappear. Then, place the resulting liquid in a cool, dark place and let it stand overnight. After the organic solvent has completely evaporated, centrifuge the remaining solution at 3000 r / min for 10 min to remove larger aggregates to obtain the polymer colloidal particle dispersion.

[0038] The particle size distribution and zeta potential of the polymer colloidal particles prepared in this embodiment were tested using dynamic light scattering (DLS). Before testing, the dispersion containing colloidal particles was vortexed to ensure thorough and uniform dispersion. Subsequently, it was filtered through a microporous membrane with a pore size of 0.225 μm to remove any possible impurities and large aggregates. The concentration of the colloidal particle dispersion was adjusted to 0.5 mg / mL, and particle size determination was performed under the same testing conditions. Figure 8 The particle size distribution of the polymer colloidal particles, measured by dynamic light scattering, is shown. The hydrodynamic diameter is 59.07 ± 4.45 nm, and the particle size distribution is relatively concentrated, indicating that the obtained nanoparticles have good size uniformity.

[0039] The performance stability of the above colloidal particle dispersion (0.5 mg / mL) was tested after standing at room temperature for 7 days. The particle size and particle size distribution index of the colloidal particles in the dispersion were measured daily using DLS. The test results are shown in the figure below. Figure 9 As shown, within the test time range, the particle size of the colloidal particles changed little, and the polydispersity index (PDI) was 0.1566 ± 0.03. The test results indicate that the colloidal particles can be stably dispersed in the solution for at least 7 days, with no significant changes in particle size and PDI. Furthermore, the PDI value remains consistently below 0.2, indicating that the system has good dispersion stability.

[0040] The colloidal particle dispersion prepared in this embodiment was diluted to 0.2 mg / mL and filtered through a microporous membrane with a pore size of 0.225 μm. After filtration, the filtrate was sonicated to ensure uniform dispersion of the nanoparticles. Then, 10 μL of the treated dispersion was dropped onto a 200-mesh carbon support membrane copper grid and allowed to dry naturally. The above dropping and drying steps were repeated three times to improve the uniformity of the colloidal particle distribution. After the sample was completely dry, the morphology of the colloidal particles was observed and analyzed using a transmission electron microscope. The test images are shown below. Figure 10 As shown, TEM observation revealed that the colloidal particles exhibited a regular near-spherical morphology with clear particle boundaries and no obvious aggregation, indicating that the polymer has good self-assembly ability in aqueous solution and relatively uniform particle size with an average particle size of 53.52±6.48 nm.

[0041] Example 6 Test the free radical scavenging ability of the polymer colloidal particles prepared in Example 5: (1) ABTS free radical scavenging experiment The free radical scavenging ability of the polycarbonate nanoparticles was evaluated using an ABTS radical scavenging assay. This method is based on the generation of stable blue-green cationic free radicals ABTS· (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) under oxidative conditions. + It has a characteristic absorption peak at 734 nm; when antioxidants are present, ABTS· + The solution is reduced to colorless ABTS, causing a decrease in absorbance. The degree of absorbance reduction characterizes the sample's free radical scavenging ability. The specific experimental steps are as follows: S1, ABTS + Preparation of working solution: Prepare 7.0 mM ABTS aqueous solution and 2.45 mM potassium persulfate aqueous solution respectively. Mix the two solutions at a volume ratio of 1:1 and let them stand at room temperature for 12 hours in the dark to allow ABTS to be completely oxidized to ABTS· + Free radicals, yielding ABTS· + Solution, then ABTS· + The solution was diluted with deionized water to adjust its absorbance at 734 nm to 0.75 ± 0.05, which was then used as the ABTS solution for the experiment. + Working fluid; S2, Free radical scavenging experiment: Take 500 μL of the ABTS· prepared in S1 above. + The working solution was mixed with 500 μL of polymer colloidal particle dispersions of different concentrations (obtained by diluting the polymer colloidal particle dispersions prepared in Example 5). The concentrations of the polymer colloidal particle dispersions were set to 0, 0.0625 mg / mL, 0.125 mg / mL, 0.25 mg / mL, 0.5 mg / mL, and 1.0 mg / mL. The resulting mixture was placed in a 1.5 mL centrifuge tube and reacted at room temperature in the dark for 24 h. After the reaction was completed, 100 μL of the reaction solution was added to a 96-well plate, with three parallel replicates for each concentration. The absorbance changes of the corresponding samples at each concentration were measured using an ELISA reader at a wavelength of 734 nm.

[0042] By comparing ABTS before and after treatment with polymer colloidal particle dispersions of different concentrations... + The change in absorbance of the solution is used to evaluate the free radical scavenging ability of polymer colloidal particles. ABTS· + The formula for calculating the clearance rate is as follows: ABTS· + Clearance rate (%) = (A0-A1) / A0×100% (1) In the formula, A0 is ABTS· + The original absorbance of the solution, and A1 is the actual absorbance of the sample.

[0043] Figure 11 To study the effects of polymer colloidal particle dispersions of different concentrations on ABTS· + The scavenging rate comparison chart shows the scavenging rate of polymer colloidal particles for ABTS at a concentration of 0.25 mg / mL. + The removal rate reached 89.89%, demonstrating extremely high removal efficiency.

[0044] Figure 12 For ABTS· + The working solution was mixed with polymer colloidal particle dispersions of different concentrations, and reacted at room temperature and in the dark for 24 hours. The UV fluorescence spectra of the resulting reaction solutions (with a polymer colloidal particle dispersion concentration of 0 denoted as Control) show that the absorbance of the solution gradually decreases with increasing polymer colloidal particle dispersion concentration. The polymer colloidal particles transfer ABTS· through electron transfer or hydrogen atom transfer reactions. + Reduction causes a decrease in the absorbance of the solution.

[0045] (2) DPPH free radical scavenging experiment To further evaluate the free radical scavenging ability of polymer colloidal particles, stable DPPH (1,1-diphenyl-2-picrylhydrazine) free radicals were used as the reactive group. DPPH free radicals exhibit a characteristic absorption peak at 517 nm. When DPPH free radicals are scavenged by antioxidants, the absorbance decreases. The free radical scavenging ability of the samples was characterized by measuring the change in absorbance. The specific experimental steps are as follows: S1. Preparation of DPPH working solution: Weigh an appropriate amount of DPPH and dissolve it in anhydrous ethanol to prepare a 0.1 mM DPPH ethanol solution. The solution should be stored under light-protected conditions and diluted before use to adjust its absorbance at a wavelength of 517 nm to 0.90 ± 0.02, which will be used as the DPPH working solution for the experiment. S2. Free radical scavenging experiment: 500 μL of the DPPH working solution prepared in S1 above was mixed with 500 μL of polymer colloidal particle dispersions of different concentrations (obtained by diluting the polymer colloidal particle dispersion prepared in Example 5). The concentrations of the polymer colloidal particle dispersions were set to 0, 0.0625 mg / mL, 0.125 mg / mL, 0.25 mg / mL, 0.5 mg / mL and 1.0 mg / mL. The resulting mixtures were placed in 1.5 mL centrifuge tubes and reacted at room temperature and in the dark for 24 h. After the reaction was completed, 100 μL of the reaction solution was added to a 96-well plate. Three parallel replicates were set for each concentration. The absorbance changes of the corresponding samples at each concentration were measured at a wavelength of 517 nm using an ELISA reader.

[0046] The scavenging ability of polymer colloidal particles for free radicals was evaluated by comparing the changes in absorbance of DPPH solutions before and after treatment with dispersions of polymer colloidal particles at different concentrations. The scavenging rate formula for DPPH· is as follows: DPPH clearance rate (%) = (B0-B1) / B0×100% (2) In the formula, B0 is the original absorbance of the DPPH solution, and B1 is the actual absorbance of the sample.

[0047] Figure 13 The graph shows a comparison of the scavenging rates of DPPH· by polymer colloidal particle dispersions at different concentrations. DPPH· is a stable organic free radical. At a concentration of 0.5 mg / mL, the polymer colloidal particles achieved a scavenging rate of 82.47% for DPPH·, demonstrating high scavenging efficiency.

[0048] Figure 14 The UV fluorescence spectra of the reaction solutions obtained after mixing DPPH working solution with polymer colloidal particle dispersions of different concentrations and reacting at room temperature and in the dark for 24 hours are shown (the concentration of polymer colloidal particle dispersions is 0, denoted as Control). It can be seen that as the concentration of polymer colloidal particle dispersions increases, the absorbance of the solution after the reaction gradually decreases, indicating that the polymer colloidal particles have a certain antioxidant capacity and can remove DPPH reactive oxygen species.

[0049] (3) The Fenton reaction system (salicylic acid method) was used to evaluate the scavenging ability of polymer colloidal particles for hydroxyl radicals (·OH). The salicylic acid method based on the Fenton reaction system was used to evaluate the hydroxyl radical scavenging ability of polymer colloidal particles. Under acidic conditions, ferrous ions (Fe...) 2+ Salicylic acid reacts with hydrogen peroxide (H₂O₂) to generate ·OH radicals. These ·OH radicals can then react with salicylic acid to form a product with characteristic absorption, exhibiting a significant absorption peak in the 510-520 nm wavelength range. When the sample possesses ·OH scavenging ability, the above reaction process can be inhibited, thereby reducing the absorbance of the system. The specific experimental steps are as follows: Preparation of S1 and ·OH reagent solutions: Prepare 6mM salicylic acid solution, 8mM ferrous sulfate (FeSO4) solution and 4mM hydrogen peroxide (H2O2) solution respectively. Then, mix 500μL of ferrous sulfate solution with 500μL of hydrogen peroxide solution, shake and react at room temperature for 10min, and then centrifuge. Take the supernatant as the ·OH reagent solution. S2. Hydroxyl radical scavenging experiment: Take 750 μL of the above ·OH reagent solution and add polymer colloidal particle dispersions of different concentrations (diluted from the polymer colloidal particle dispersion prepared in Example 5) to make the concentration of polymer colloidal particles in the mixture 0, 0.0625 mg / mL, 0.125 mg / mL, 0.25 mg / mL, 0.5 mg / mL and 1.0 mg / mL. After mixing evenly, react at 37℃ for 24 h. After the reaction is completed, centrifuge the reaction solution at 10000 r / min for 1 min. Take 750 μL of supernatant and add it to 250 μL of salicylic acid solution (6 mM). Mix evenly and react for 10 min. Then take 100 μL of the reaction solution and add it to a 96-well plate. Set up 3 parallel replicates for each concentration. Use an ELISA reader to measure the absorbance change of the corresponding samples at a wavelength of 510 nm.

[0050] The scavenging ability of the polymer colloidal particles for hydroxyl radicals was evaluated by comparing the changes in absorbance of the system before and after treatment with different concentrations of polymer colloidal particles. The formula for calculating the ·OH scavenging rate is as follows: ·OH scavenging rate (%) = (C0-C1) / C0×100% (3) In the formula, C0 is the absorbance of the control group and C1 is the absorbance of the experimental group.

[0051] Figure 15 The graph shows a comparison of the scavenging rates of ·OH by polymer colloidal particle dispersions at different concentrations. ·OH is one of the most reactive and destructive ROS. At a concentration of 0.5 mg / mL, the polymer colloidal particles achieved a scavenging rate of 83.08% for ·OH, demonstrating high scavenging efficiency. This indicates that the polymer colloidal particles can not only scavenge stable free radicals but also effectively inhibit highly reactive oxide species, thus exhibiting a broad-spectrum and highly efficient ROS scavenging ability.

[0052] Figure 16 The UV fluorescence spectra of the reaction solutions obtained after mixing ·OH reagent solution with polymer colloidal particle dispersions of different concentrations and reacting at 37℃ for 24 h are shown. The comparison shows that as the concentration of polymer colloidal particle dispersion increases, the absorbance of the reaction solution gradually decreases, indicating that the polymer colloidal particles have a certain antioxidant effect and can remove ·OH.

[0053] Example 7 Cell compatibility of the polymer colloidal particles prepared in Example 5 was tested: The cytotoxicity of polymer colloidal particles to rat cochlear hair cells OC-1 and mouse fibroblasts L929 was assessed using the MTT assay. Specifically, OC-1 or L929 cells were inoculated at approximately 1 × 10⁻⁶ cells per cell line. 4Cells were seeded at a density of [number] cells / well, diluted with DMEM medium, and seeded into 96-well plates. After incubation at 37°C and 5% CO2 for 24 h, polymer colloidal particle dispersions at concentrations of 1.6 μg / mL, 8 μg / mL, 40 μg / mL, 200 μg / mL, and 1000 μg / mL were added. A cell control group without polymer colloidal particles and a cell-free blank group were also included. After incubation for another 24 h, the medium was removed, and 100 μL of medium containing 10 μL of 5 mg / mL MTT assay solution was added to each well. After incubation at 37°C in the dark for 4 h, the supernatant was carefully discarded, and 100 μL of DMSO was added to each well. The plates were then incubated for another 2 h to dissolve the formazan crystals. The absorbance at 570 nm was measured using a microplate reader, and cell viability was calculated using the following formula: Cell viability = (N) s -N b ) / (N c -N b ) × 100% Where N s N c N b The absorbance values ​​are for the sample well, control well, and blank well, respectively.

[0054] Figure 17 The graph shows a comparison of the survival rates of OC-1 and L929 cells in polymer colloidal particle dispersions at different concentrations. It can be seen that within the test concentration range of 1.6-1000 μg / mL, the viability of both OC-1 and L929 cells remained above 98%, without a significant concentration-dependent decrease. Specifically, the viability of L929 cells was approximately 118% at a polymer colloidal particle dispersion concentration of 1.6 μg / mL, and the cell viability remained at approximately 100% even as the polymer colloidal particle dispersion concentration increased to 1000 μg / mL. The survival rate of OC-1 cells remained stable between 98% and 102% across all concentration ranges. These results indicate that the polymer colloidal particles exhibit extremely low cytotoxicity over a wide concentration range, demonstrate excellent biocompatibility with both normal and tumor cells, and possess good safety for in vivo application.

[0055] Example 8 A drug-loaded polymer colloidal particle, using Nile Red as a hydrophobic model drug, is prepared as follows: Weigh 4 mg of mPEG-b-PTESPBMTC prepared in Example 2 10Dissolve 1 mg of Nile Red in 100 μL of chloroform and 1 mg of Nile Red in 50 μL of dimethyl sulfoxide. Mix the two solutions thoroughly on a constant temperature (20 °C) vibrating mixer to obtain a homogeneous organic phase solution. Then, under ultrasonic conditions, rapidly add the obtained organic phase solution to 4 mL of distilled water and continue ultrasonic treatment for 10 min to obtain a dispersion. Place the obtained dispersion in a cool, dark place overnight to promote the stability of the nanoparticle structure. Then, dialyze the dispersion in ultrapure water for 24 h (3500 Da) to remove organic solvents and unencapsulated small molecules. After dialysis, centrifuge the solution at 3000 r / min for 10 min to remove larger aggregates and unencapsulated Nile Red. Collect the supernatant as the drug-loaded polymer colloidal particle dispersion.

[0056] Example 9 The in vitro drug release behavior of the drug-loaded polymer colloidal particles prepared in Example 8 was tested: Two mL of H2O2 solutions of different concentrations were mixed thoroughly with two mL of the drug-loaded polymer colloidal particle dispersion obtained in Example 8 to achieve final H2O2 concentrations of 0, 10 mM, 50 mM, and 100 mM. The mixtures were then placed in a 37°C constant-temperature shaking incubator (100 rpm). At preset time points (0, 24 h, 48 h, and 72 h), 100 μL of the mixture samples were added to 96-well plates, with three replicates per group. The absorbance of the samples at 490 nm was measured using a multi-mode microplate reader to evaluate the responsive release behavior of the drug-loaded polymer colloidal particles under different concentrations of reactive oxygen species (ROS). The same system without H2O2 served as a negative control. The cumulative drug release efficiency was calculated using the following formula: Cumulative drug release efficiency (%) = (F0 - F) t ) / F0×100%(4) Among them, F0 and F t The fluorescence intensities are denoted as initial and t, respectively.

[0057] Figure 18 This chart compares the cumulative drug release efficiency of drug-loaded polymer colloidal particles at different concentrations of H2O2 over different time periods. The drug-loaded polymer colloidal particles exhibit a clear ROS-triggered release characteristic in the presence of H2O2. Specifically, at 72 hours, the cumulative drug release was approximately 36% under 10 mM H2O2, approximately 56% under 50 mM H2O2, and reached approximately 80% under 100 mM H2O2. In contrast, the drug release within 72 hours was only 16% under H2O2-free conditions. This confirms that the trisulfide bonds undergo oxidation in an oxidizing environment, inducing a change in the hydrophilicity of the nanoparticles, thereby significantly promoting the rapid release of the encapsulated drug.

[0058] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A six-membered bicyclic aliphatic carbonate monomer containing a thioether bond, characterized in that, Its molecular structure is shown in equation (1) below: （1）。 2. A method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond as described in claim 1, characterized in that, The specific steps are as follows: 1) Synthesis of dihydroxy monomers containing trisulfide bonds: 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester is reacted with dimercaptoethyl sulfide in a mercapto-olefin "click" chemical reaction, and then purified to obtain dihydroxy monomers containing trisulfide bonds; 2) Synthesis of a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond: The dihydroxy monomer containing a trithioether bond obtained in step 1) is subjected to a cyclization reaction with ethyl chloroformate, and then purified to obtain a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond.

3. The method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 2, characterized in that, In step 1), the molar ratio of 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester to dimercaptoethyl sulfide is 2-4:

1.

4. The method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 2, characterized in that, Step 1) The conditions for the "click" chemical reaction of the mercapto-ene are: under an inert atmosphere, using azobisisobutyronitrile as an initiator, the reaction is carried out at 60-80℃ for 12-60h.

5. The method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 2, characterized in that, Step 1) 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester and dimercaptoethyl sulfide undergo a mercapto-olefin "click" chemical reaction. The specific steps are as follows: 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester and dimercaptoethyl sulfide are dissolved in anhydrous DMF, and then azobisisobutyronitrile is added. The reaction system is subjected to liquid nitrogen freezing-thawing cycle to remove residual oxygen in the system, and then the reaction is carried out. After the reaction is completed, the reaction solution is concentrated under reduced pressure. The crude product is purified by silica gel column chromatography to obtain the product.

6. The method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 5, characterized in that, The mass-to-volume ratio of 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester to anhydrous DMF is 0.05-0.1 g / mL; the molar ratio of 2,2-bis(hydroxymethyl)propionic acid-2-propenyl ester to azobisisobutyronitrile is 2-4:

1.

7. The method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 2, characterized in that, Step 2) The molar ratio of the trisulfide-containing dihydroxy monomer to ethyl chloroformate is 1:2-6.

8. The method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 2, characterized in that, Step 2) The cyclization reaction conditions are: under an inert atmosphere, triethylamine is used as an acid-binding agent, and the reaction is carried out at 10-30℃ for 4-12 hours.

9. The method for preparing a six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 2, characterized in that, Step 2) The cyclization reaction of the trisulfide-containing dihydroxy monomer with ethyl chloroformate is carried out as follows: The trisulfide-containing dihydroxy monomer is dissolved in anhydrous tetrahydrofuran. Under ice bath conditions, ethyl chloroformate is added to the resulting solution, and then a tetrahydrofuran solution of triethylamine is slowly added dropwise. After the addition is completed, the cyclization reaction is carried out. After the reaction is completed, the triethylamine hydrochloride precipitate is removed by filtration. The filtrate is concentrated under reduced pressure, and the crude product is purified by silica gel column chromatography to obtain the product.

10. The use of the six-membered bicyclic aliphatic carbonate monomer containing a thioether bond according to claim 1 in the preparation of a drug delivery carrier for treating oxidative stress diseases, characterized in that, The specific application method is as follows: the six-membered bicyclic aliphatic carbonate monomer containing thioether bonds is polymerized, or copolymerized with other polymerizable monomers and macromolecular monomers to form block polymers or random copolymers, which are used as drug carriers.

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