pH / hypoxia dual-responsive polymers, nanomicelles, their preparation methods and applications

Abstract

This invention belongs to the field of nanomedicine technology, specifically relating to a pH / hypoxia dual-responsive polymer, nanomicelles, their preparation method, and applications. The pH / hypoxia dual-responsive polymer is a hydroxyethyl deacetylated chitosan modified with p-nitrobenzyl chloroformate and cinnamaldehyde. Ropivacaine is loaded onto it and prepared into nanomicelles for use as a drug delivery system after tumor surgery. Due to its acid sensitivity and hypoxia response, it can intelligently identify the tumor microenvironment, achieving precise drug delivery.

Description

Technical Field

[0001] This invention belongs to the field of nanopharmaceutical technology, specifically relating to a pH / hypoxia dual-responsive polymer, nanomicelles, their preparation method and application. Background Technology

[0002] Cancer pain refers to pain directly caused by cancer or cancer-related lesions and anti-cancer treatments. It is often chronic pain and a common symptom in cancer patients. In clinical practice, postoperative pain after tumor resection cannot be completely controlled by analgesics, and long-term use of high doses can easily lead to side effects such as drug tolerance, addiction, and neurological dysfunction. Based on this, some studies have proposed encapsulating analgesics into nanocarriers. Nanocarriers are nanoscale delivery systems with extremely wide applications, playing a key role in nanomedicine fields such as multimodal imaging of human diseases, drug delivery, and targeted therapy. However, traditional nanocarriers have limitations, including drug leakage and stability issues. To overcome these problems, methods such as coating NPs and using stimulus-responsive nanocarriers have been considered. Stimulus-responsive drug delivery systems are systems in which drugs are released or delivered through stimulation. In recent years, research on stimulus-responsive nanocarriers has made great progress, and many nanocarriers have been designed to respond to physicochemical changes in external stimuli (such as ultrasound, heat, light, and magnetic fields) and internal stimuli (including pH, redox potential, hypoxia, and enzymes). Stimulus-responsive nanocarriers can respond to physicochemical and pathological factors within the disease area, thereby improving the specificity of drug delivery, overcoming multidrug resistance, and achieving accurate diagnosis and precise treatment.

[0003] Polymer micelles possess excellent self-assembly capabilities, increasing drug solubility, enhancing drug loading capacity, reducing adverse reactions, and improving drug bioavailability. Their unique shell-core structure allows for the free selection of suitable micelle carriers based on drug properties. By linking specific antibodies, ligands, or certain stimuli-sensitive systems to the hydrophilic segments of the micelles, targeted drug delivery can be achieved. Currently, most anticancer drugs or analgesics suffer from short half-lives after injection, failing to achieve long-term circulation effects in vivo, and their drug delivery lacks targeting. Therefore, it is necessary to develop polymer micelles that can intelligently respond to the unique microenvironment of diseased tissues (such as tumors) to achieve precise drug release. Summary of the Invention

[0004] The present invention aims to provide a pH / hypoxia dual-responsive polymer, nanomicelles, their preparation method, and applications. This polymer nanomicelle exhibits hypoxia-responsive and acid-responsive properties, resulting in good drug delivery specificity.

[0005] To solve the above problems, the technical solution provided by the present invention is as follows:

[0006] In a first aspect, the present invention provides a pH / hypoxia dual-responsive polymer, wherein the pH / hypoxia dual-responsive polymer is a hydroxyethyl deacetylated chitosan modified with p-nitrobenzyl chloroformate and cinnamaldehyde.

[0007] In a second aspect, the present invention provides a method for preparing the above-mentioned pH / hypoxia dual-responsive polymer, wherein the preparation method comprises: adding p-nitrobenzyl chloroformate and cinnamaldehyde to a dimethyl sulfoxide solution of hydroxyethyl deacetylated chitosan, stirring continuously at room temperature until the reaction is complete, dialysis with pure water, and freeze-drying to obtain the pH / hypoxia dual-responsive polymer.

[0008] Furthermore, the synthetic route for preparing the above-mentioned pH / hypoxia dual-responsive polymer is as follows:

[0009]

[0010] Furthermore, in the above-mentioned method for preparing the pH / hypoxia dual-response polymer, the molar ratio of hydroxyethyl deacetylated chitosan, p-nitrobenzyl chloroformate, and cinnamaldehyde is 1:(0.5-3):(0.6-5).

[0011] Furthermore, in the above-mentioned method for preparing the pH / hypoxia dual-responsive polymer, the dimethyl sulfoxide solution of hydroxyethyl deacetylated chitosan also contains a catalyst.

[0012] Furthermore, in the above-mentioned method for preparing the pH / hypoxia dual-responsive polymer, the catalyst is N,N-diisopropylethylamine.

[0013] Furthermore, in the above-mentioned method for preparing the pH / hypoxia dual-responsive polymer, the reaction time is 12-24 h.

[0014] A third aspect of the present invention provides a pH / hypoxia dual-responsive polymer nanomicelle, which is prepared from the above-described pH / hypoxia dual-responsive polymer.

[0015] In a fourth aspect, the present invention provides a method for preparing the above-mentioned pH / hypoxia dual-responsive polymer nanomicelles, wherein the preparation method comprises: dissolving the above-mentioned pH / hypoxia dual-responsive polymer in a solvent, and obtaining the pH / hypoxia dual-responsive polymer nanomicelles by dialyzing; wherein the mass / volume ratio of the pH / hypoxia dual-responsive polymer to the solvent is (5-10):1.

[0016] In a fifth aspect, the present invention provides the use of the above-described pH / hypoxia dual-responsive polymer or pH / hypoxia dual-responsive polymer nanomicelles as a drug carrier in the preparation of a drug.

[0017] In a sixth aspect, the present invention provides an oncology drug obtained by loading ropivacaine onto the aforementioned pH / hypoxia dual-responsive polymer.

[0018] Furthermore, the tumor drug is a drug used for postoperative analgesia and treatment of tumors.

[0019] Furthermore, the tumor drug is used to target and deliver analgesics in vivo to suppress postoperative pain after tumor resection, particularly postoperative cancer-related neuropathic pain.

[0020] Furthermore, the pain corresponding to the analgesia is pain directly or indirectly caused after tumor resection, including pain caused by direct damage to the nervous system due to tumor recurrence or metastasis, or pain caused by postoperative treatment.

[0021] Furthermore, the tumor drug also includes pharmaceutically acceptable excipients.

[0022] The pH / hypoxia dual-responsive polymer, nanomicelles, their preparation method, and applications according to embodiments of the present invention have at least one of the following advantages:

[0023] (1) In this invention, p-nitrobenzyl chloroformate and cinnamaldehyde are used to modify hydroxyethyl deacetylated chitosan. The hypoxia-responsive group is linked to the amino group of chitosan. The imine bond formed by cinnamaldehyde and chitosan amino group has strong acid sensitivity. Then, the drug is encapsulated in a polymer nanomicelle carrier. The prepared polymer nanomicelle has hypoxia responsiveness and acid sensitivity. The hypoxia responsiveness and acid sensitivity design enables the micelles to intelligently respond to the unique microenvironment of diseased tissue (such as tumor), realize the precise release of drugs, thereby significantly improving the efficacy and reducing side effects.

[0024] (2) It can achieve targeted delivery of analgesic drugs in vivo to suppress postoperative pain after tumor resection, especially postoperative cancer-related neuropathic pain. At the same time, it prolongs the blood circulation time of the drug in the body, improves the specificity of drug delivery, improves the bioavailability of the drug, overcomes multidrug resistance, reduces adverse drug reactions and side effects, and achieves accurate diagnosis and precise treatment.

[0025] (3) The nanocarrier prepared by the present invention can prevent particle aggregation, reduce particle binding with plasma proteins in vivo, prolong the blood circulation time of the drug, and improve the bioavailability of the drug in the nanocarrier.

[0026] (4) The polymer nanomicelles prepared by this invention have good self-assembly ability, which can increase drug solubility, enhance drug loading capacity, reduce adverse reactions, and improve drug bioavailability. Their unique shell-core structure allows for the free selection of suitable micelle carriers according to the properties of the drug. By linking specific antibodies, ligands, or certain stimuli-sensitive systems to the hydrophilic segments of the micelles, drug localization and delivery can be achieved. In addition, their preparation is simple and convenient, their surface is easy to modify, and they can be rapidly mass-produced. Attached Figure Description

[0027] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof. In the accompanying drawings:

[0028] Figure 1 The hydrated particle size distribution of the polymer nanomicelles loaded with ropivacaine obtained in Example 2 is shown in the diagram.

[0029] Figure 2 The potential diagram of polymer nanomicelles loaded with ropivacaine obtained in Example 2;

[0030] Figure 3 This is a transmission electron microscope (TEM) image of polymer nanomicelles loaded with ropivacaine obtained in Example 2.

[0031] Figure 4 The in vitro drug release curve obtained in Experiment Example 1;

[0032] Figure 5 The images of cell fluorescence and the statistical results of fluorescence intensity are shown in the figure for Experiment Example 2, which were taken using a laser confocal microscope.

[0033] Figure 6 The image shows the fluorescence intensity changes of the bilateral dorsal root ganglia as captured by a laser confocal microscope in Experiment Example 3.

[0034] Figure 7 This is a graph showing the changes in body weight and tumor volume growth in female BALB / c mice in different treatment groups within 15 days after melanoma resection in Experiment Example 4.

[0035] Figure 8 This is a statistical graph showing the changes in mechanical pain threshold in mice 2, 6, 12, and 24 hours after drug administration in Experiment Example 5.

[0036] Figure 9 This is a statistical graph showing the changes in the thermal pain threshold of mice in Experiment 5 at 2 hours, 6 hours, 12 hours, and 24 hours after drug administration. Detailed Implementation

[0037] To further understand the present invention, preferred embodiments of the present invention will be described in detail below with reference to examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the claims of the present invention.

[0038] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0039] In one typical embodiment of this application, a pH / hypoxia dual-responsive polymer is provided, which is a hydroxyethyl deacetylated chitosan modified with p-nitrobenzyl chloroformate and cinnamaldehyde.

[0040] In a second typical embodiment of this application, a method for preparing a pH / hypoxia dual-responsive polymer is provided, specifically: p-nitrobenzyl chloroformate and cinnamaldehyde are added to a dimethyl sulfoxide solution of hydroxyethyl deacetylated chitosan, and the mixture is stirred at room temperature until the reaction is complete. After dialyzing with pure water, the mixture is freeze-dried to obtain the pH / hypoxia dual-responsive polymer.

[0041] In the preparation method of the above-mentioned pH / hypoxia dual-responsive polymer, hydroxyethyl deacetylated chitosan is modified with p-nitrobenzyl chloroformate and cinnamaldehyde. Hypoxia-responsive groups are linked to the amino groups of chitosan. The imine bond formed by cinnamaldehyde and the amino groups of chitosan exhibits strong acid sensitivity, resulting in a pH / hypoxia dual-responsive polymer with strong hypoxia responsiveness and acid sensitivity, exhibiting specificity for hypoxic and acidic microenvironments. The dual targeting of hypoxia response and acid sensitivity has certain synergistic advantages. Micelles initially release the drug in the tumor microenvironment (low pH) through acid sensitivity. Upon further penetration into the hypoxic core region, the hypoxia response mechanism triggers a secondary release. Precise delivery can reduce drug waste at non-target sites and prevent tumor cells from developing drug resistance due to insufficient drug concentration.

[0042] In order to have sufficient hypoxia-responsive groups, in some preferred embodiments of the present invention, the molar ratio of hydroxyethyl deacetylated chitosan, p-nitrobenzyl chloroformate and cinnamaldehyde is 1:(0.5-3):(0.6-5).

[0043] In some preferred embodiments of the present invention, the dimethyl sulfoxide solution of hydroxyethyl deacetylated chitosan also contains a catalyst, such as N,N-diisopropylethylamine.

[0044] In some preferred embodiments of the present invention, the preparation method of the pH / hypoxia dual-responsive polymer is as follows: hydroxyethyl deacetylated chitosan and N,N-diisopropylethylamine are dissolved in dimethyl sulfoxide (DMSO), and the mixture is magnetically stirred at 0°C-4°C until homogeneous. Then, p-nitrobenzyl chloroformate and cinnamaldehyde are added, and the mixture is transferred to room temperature and stirred until the reaction is complete. After dialyzing with pure water, the mixture is freeze-dried to obtain the pH / hypoxia dual-responsive polymer. Preferably, the magnetic stirring time is 0.5-1 h; the reaction time is 12-24 h. Preferably, dialysis is performed with pure water using a dialysis bag with a molecular weight cutoff of 3500-14000, and the dialysis time is 2-3 days. Our research group has found that dimethyl sulfoxide (DMSO) can dissolve hydroxyethyl deacetylated chitosan very well compared to other organic solvents. Therefore, dimethyl sulfoxide (DMSO) is used as the solvent in the preparation of the pH / hypoxia dual-responsive polymer.

[0045] In a third typical embodiment of the present invention, a pH / hypoxia dual-responsive polymer nanomicelle is provided, which is prepared from the above-mentioned pH / hypoxia dual-responsive polymer.

[0046] In a fourth typical embodiment of the present invention, a method for preparing pH / hypoxia dual-responsive polymer nanomicelles is provided. The method comprises: dissolving the pH / hypoxia dual-responsive polymer of claim 1 in a solvent, and then dialyzing to obtain the pH / hypoxia dual-responsive polymer nanomicelles; the mass / volume ratio of the pH / hypoxia dual-responsive polymer to the solvent is (5-10):1. Preferably, the molecular weight cutoff of the dialysis bag used for dialysis can be 3500-14000; specifically, dialysis with pure water can be performed for 6-8 hours under magnetic stirring.

[0047] In a fourth exemplary embodiment of the present invention, the use of the above-described pH / hypoxia dual-responsive polymer or pH / hypoxia dual-responsive polymer nanomicelles as described above in the preparation of drugs as drug carriers is provided.

[0048] In a fifth typical embodiment of the present invention, an oncology drug is provided, which is obtained by loading ropivacaine onto the aforementioned pH / hypoxia dual-responsive polymer. Compared with opioids or other analgesics, ropivacaine has lower toxicity and fewer side effects. This oncology drug is a drug delivery system loaded with ropivacaine. Due to the hypoxia response and acid sensitivity of the pH / hypoxia dual-responsive polymer, it can be used after tumor surgery to specifically target the tumor microenvironment, achieve precise drug delivery, and solve the problems of drug leakage and stability.

[0049] In some preferred embodiments of the present invention, the tumor drug is prepared by: slowly adding water dropwise to an organic mixed solution containing a pH / hypoxia dual-response polymer and ropivacaine; stirring at room temperature for 3-6 hours after the addition is complete; transferring the resulting solution to a dialysis bag; and dialyzing with pure water for 6-8 hours under magnetic stirring to remove free drug, thereby obtaining the tumor drug.

[0050] In a preferred embodiment of the present invention, the mass ratio of the pH / hypoxia dual-responsive polymer to ropivacaine in the organic mixed solution of the pH / hypoxia dual-responsive polymer and ropivacaine is (3-5):1.

[0051] In some preferred embodiments of the present invention, the hydrated particle size of the above-mentioned tumor drug is 200-300 nm.

[0052] The present invention will be described in detail below through embodiments. Unless otherwise specified, all raw materials used in the following embodiments are commercially available products.

[0053] Example 1: Preparation of pH / hypoxia dual-responsive polymers

[0054] Hydroxyethyl deacetylated chitosan (GC) and N,N-diisopropylethylamine (DIPEA) (GC / DIPEA: 1 / 1.5, mol / mol) were dissolved separately in 2 mL of dimethyl sulfoxide (DMSO). The mixture was then placed in a 50 mL round-bottom flask and magnetically stirred at 0 °C for 0.5–1 hour. Next, p-nitrobenzyl chloroformate (NBCF) and cinnamaldehyde (CA) dissolved in 1 mL of DMSO (GC / NBCF / CA: 1 / 1.5 / 2, mol / mol / mol) were added. The mixture was then transferred to room temperature and stirred for 12–24 hours until the reaction was complete. The mixture was dialyzed against pure water for 48 hours using a dialysis bag with a molecular weight cutoff of 3500 (MW). The dialyzed product, GC-NBCF-CA, was then freeze-dried to prepare a powder.

[0055] Example 2: Preparation of polymeric nanomicelles (PMs / Rop) loaded with ropivacaine

[0056] The pH / hypoxia dual-responsive polymer (GC-NBCF-CA):ropivacaine was controlled at a mass ratio of 4:1 during preparation. The pH / hypoxia dual-responsive polymer and the drug were dissolved in dimethyl sulfoxide. Subsequently, the organic solution and pure water were slowly added dropwise at a volume ratio of 1:4 and mixed. The mixture was magnetically stirred at room temperature for 3-4 hours. The resulting solution was transferred to a dialysis bag (MW=3500) and dialyzed with pure water for 6 hours under magnetic stirring to remove free ropivacaine. Finally, polymer nanomicelles (PMs / Rop) loaded with ropivacaine were obtained.

[0057] Example 3: Preparation of polymer nanomicelles loaded with Rhodamine B

[0058] In Example 2, ropivacaine was replaced with rhodamine B, while the other process parameters remained the same.

[0059] Test Example 1

[0060] The particle size and potential of the ropivacaine-loaded polymer nanomicelles (PMs / Rop) obtained in Example 2 were measured using a Malvern particle size analyzer. The results are as follows: Figure 1 , Figure 2 As shown. According to Figure 1 It can be seen that the particle size of PMs / Rop is between 200-300 nm. According to... Figure 2 It can be seen that the potential of PMs / Rop is positive.

[0061] Transmission electron microscopy was used to image the polymer nanomicelles (PMs / Rop) loaded with ropivacaine obtained in Example 2. The results are as follows: Figure 3 It can be seen that the prepared polymer nanomicelles are uniformly spherical.

[0062] Example 1: Using chitosan derivatives modified with benzyl chloroformate (BCF), p-nitrobenzyl chloroformate (NBCF), p-nitrobenzyl chloroformate (NBCF), and cinnamaldehyde (CA), ropivacaine-loaded polymeric micelles (i.e., GC-BCF-PMs / Rop, GC-NBCF-PMs / Rop, GC-NBCF-CA-PMs / Rop) were prepared. 1 mL of each polymeric micelle solution was placed in a dialysis bag and then immersed in 20 mL of phosphate-buffered saline (PBS) under different conditions (i.e., weakly alkaline pH = 7.4, normoxia; weakly acidic pH = 6.0, normoxia; weakly acidic, hypoxia). Samples were taken at different time points, and the ropivacaine drug content in the dialysis fluid was detected by high-performance liquid chromatography (HPLC). In vitro drug release curves were plotted.

[0063] In vitro drug release results as follows Figure 4As shown in Figure A, the drug release curves of GC-BCF-PMs / Rop showed no difference under weakly alkaline (pH 7.4, normoxia), weakly acidic (pH 6.0, normoxia), and hypoxic (Hypoxia) conditions, and the cumulative drug release rate was low, indicating that GC-BCF does not exhibit hypoxia-responsiveness or pH-responsiveness. Figure B shows that GC-NBCF-PMs / Rop released more rapidly and had the highest cumulative drug release under hypoxic (Hypoxia) conditions, while the release showed no difference and the cumulative drug release rate was low under weakly alkaline (pH 7.4, normoxia), weakly acidic (pH 6.0, normoxia) conditions, indicating that GC-NBCF exhibits hypoxia-responsiveness. Under hypoxia conditions, the hydrophobic nitro groups transform into hydrophilic amino groups, promoting rapid drug release. As shown in Figure C, the drug release rate and cumulative release rate of GC-NBCF-CA-PMs / Rop were higher under weakly acidic conditions (pH=6.0, normoxic Normoxia) and hypoxic conditions than under weakly alkaline conditions (pH=7.4, normoxic Normoxia). This indicates that GC-NBCF-CA has a dual pH / hypoxia response. Under weakly acidic conditions, the acid-sensitive imine bond breaks, and the polymer micelles decompose, promoting rapid drug release.

[0064] Experimental Example 2: B16 cells were seeded in 24-well plates. When the cell density reached 60%, 5 μg / mL of rhodamine B-loaded polymer nanomicelles modified with BCF, NBCF, NBCF, and CA were added to the B16 cells. After culturing under normoxic conditions for 1 hour, the cells were then placed under normoxic (21% O2) and hypoxic (1% O2) conditions for 4 hours, respectively. The cells were fixed with 4% paraformaldehyde, and the nuclei were stained with DAPI for 10 minutes. Images were taken using a laser confocal microscope. Figure 5 The left figure shows the fluorescence intensity of Rhodamine B in cells observed by CLSM (from top to bottom, the left figures are GC-BCF-PMs / RhB, GC-NBCF-PMs / RhB, and GC-NBCF-CA-PMs / RhB), and the right figure shows the statistical graph of Rhodamine B fluorescence intensity in cells (n=5, ***P<0.001, mean±SD).

[0065] according to Figure 5 It can be seen that the NBCF-modified polymer nanomicelles loaded with the fluorescent dye Rhodamine B showed a significant increase in cell fluorescence intensity under hypoxic conditions, which was statistically significant.

[0066] Experimental Example 3: Polymer nanomicelles loaded with rhodamine B and modified with BCF, NBCF, NBCF, and CA were injected intrathecally into a melanoma resection model mouse. Six hours later, bilateral dorsal root ganglia were harvested, stained with fluorescence, and photographed using a laser confocal microscope. The results are as follows: Figure 6 As shown, the top figure shows the fluorescence intensity of rhodamine B in the bilateral DRGs of model mice after tumor resection detected by CLSM (from left to right in the top figure are GC-BCF-PMs / RhB, GC-NBCF-PMs / RhB, and GC-NBCF-CA-PMs / RhB). The bottom figure is a statistical graph of the fluorescence intensity of rhodamine B in the bilateral DRGs of model mice after melanoma resection (n=3, **P<0.01, mean±SD). The fluorescence intensity of the dorsal root ganglion on the modeling side was significantly increased, and the results were statistically significant.

[0067] Experiment Example 4: A melanoma model was established by intramuscularly injecting 100 μL of mouse melanoma (B16) cells into the vicinity of the sciatic nerve in the left hind limb using a syringe. The tumor volume reached 100 mm². 3 Surgical resection was performed. Starting on postoperative day 3, mice were injected with PBS, GC-PMs / Rop, GC-NBCF-PMs / Rop, and GC-NBCF-CA-PMs / Rop at a dose of 5 mg / kg, once every other day. Changes in mouse body weight and tumor growth were recorded. Results are as follows... Figure 7 As shown, there was no significant difference in body weight among the mice in each group. The PBS group was the first to experience tumor recurrence after resection and had the highest recurrence rate. The size of the recurrent tumors showed that, compared with the other treatment groups, the recurrent tumors treated with GC-NBCF-CA-PMs / Rop were smaller and lighter.

[0068] Experimental Example 5: Polymer nanomicelles loaded with ropivacaine and modified with NBCF and CA were injected intrathecally into mice with melanoma resection. The analgesic effect was tested by hyperalgesia behavior experiments such as mechanical pain and thermal pain.

[0069] Three days after melanoma resection, the mechanical and thermal pain thresholds of mice were measured. Ropivacaine-loaded polymer nanomicelles modified with NBCF and CA were injected intrathecally into the mice, which were then a model of melanoma resection. The mechanical and thermal pain thresholds of the mice were subsequently measured at 2, 6, 12, and 24 hours after administration. Figure 8 , 9 The results showed that intrathecal injection of ropivacaine-loaded polymer nanomicelles modified with NBCF and CA significantly increased the pain threshold in mice after melanoma resection at 2, 6, 12, and 24 hours, and the results were statistically significant, indicating that the ropivacaine-loaded polymer nanomicelles modified with NBCF and CA had a good analgesic effect.

[0070] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the scope of the invention. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a pH / hypoxia dual-responsive polymer, characterized in that, The preparation method is as follows: p-nitrobenzyl chloroformate and cinnamaldehyde are added to a dimethyl sulfoxide solution of hydroxyethyl deacetylated chitosan. The mixture is stirred at room temperature until the reaction is complete. After dialyzing with pure water, the mixture is freeze-dried to obtain the pH / hypoxia dual-response polymer. The molar ratio of hydroxyethyl deacetylated chitosan, p-nitrobenzyl chloroformate, and cinnamaldehyde was 1:(0.5-3):(0.6-5). The dimethyl sulfoxide solution of the hydroxyethyl deacetylated chitosan also contains a catalyst; The catalyst is N,N-diisopropylethylamine.

2. The preparation method according to claim 1, characterized in that, The reaction time is 12-24 hours.

3. A pH / hypoxia dual-responsive polymer prepared by the preparation method as described in claim 1 or 2.

4. A pH / hypoxia dual-responsive polymer nanomicelle, characterized in that, The pH / hypoxia dual-responsive polymer nanomicelles are prepared from the pH / hypoxia dual-responsive polymer of claim 3.

5. A method for preparing pH / hypoxia dual-responsive polymer nanomicelles as described in claim 4, characterized in that, The preparation method is as follows: The pH / hypoxia dual-responsive polymer of claim 3 was dissolved in a solvent and dialyzed to obtain the pH / hypoxia dual-responsive polymer nanomicelles. The mass / volume ratio of the pH / low oxygen dual-responsive polymer to the solvent is (5-10):

1.

6. The use of the pH / hypoxia dual-responsive polymer as described in claim 3 or the pH / hypoxia dual-responsive polymer nanomicelles as described in claim 4 in the preparation of drugs as drug carriers.

7. A tumor drug, characterized in that, The tumor drug is obtained by loading ropivacaine onto the pH / hypoxia dual-responsive polymer of claim 3.

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