Polymer nanoparticle with bone targeting, acid environment neutralization and oxidation resistance characteristics and preparation method thereof

Abstract

The invention relates to the field of high polymer materials and medical engineering, in particular to a high polymer nanoparticle with bone targeting, acid environment neutralization and oxidation resistance characteristics and a preparation method of the high polymer nanoparticle. The polymer nanoparticle is prepared from the following raw materials: a zoledronic acid modified polycaprolactone-polypeptide copolymer, the chemical structural formula of the copolymer is as follows: # imgabs0. The polymer nanoparticles prepared by taking the zoledronic acid modified polycaprolactone-polypeptide copolymer as a raw material have the advantages of bone targeting, excellent oxidation resistance and capability of neutralizing an acid environment. The polymer nanoparticles can exert significant efficacy (oxidation resistance and acid environment neutralization) for treating osteoporosis only by means of intrinsic activity of the materials of the polymer nanoparticles, so that a series of toxicity problems possibly caused by traditional drugs are substantially reduced fundamentally, and a brand new scheme is provided for treatment of osteoporosis.

Description

Technical Field

[0001] The present invention relates to the fields of polymer materials and medical engineering, and in particular to a polymer nanoparticle having the properties of bone targeting, neutralizing acidic environment and anti-oxidation, and a preparation method thereof. Background Art

[0002] Osteoporosis is a common systemic bone disease, which is mainly characterized by decreased bone mass and damage to the microstructure of bone tissue, which leads to increased bone brittleness and makes patients very susceptible to fractures. The disease is particularly common in postmenopausal women and elderly men. With the advent of an aging society, the incidence of osteoporosis has increased year by year and has become one of the global health problems. At present, traditional drugs (such as estrogen, statins, etc.) are usually used to treat osteoporosis patients, but due to the special properties of bone tissue such as hardness and complex structure, these drugs are difficult to accurately reach the target site, lack of bone targeting, and increase the difficulty of treatment.

[0003] In addition, in the process of osteoporosis, abnormal activation of osteoclasts is considered to be the core of the pathological mechanism. During their activation process, osteoclasts secrete a large amount of acidic substances, causing the pH value of the bone tissue microenvironment to drop to an acidic environment of about 4.0. Studies have shown that the acidic environment is the key initiating factor for osteoclasts to destroy bone tissue and is also a necessary prerequisite for the occurrence and development of osteoporosis. Therefore, regulating the acidic environment of bone tissue to restore its normal pH level (neutral) has become the key to treating osteoporosis.

[0004] In recent years, the application of nanotechnology in the medical field has provided new ideas for the treatment of osteoporosis. Nanomaterials have great potential in the treatment of bone-related diseases due to their excellent biocompatibility, stability and targeting. However, existing nanomaterials often have insufficient antioxidant properties. The occurrence and development of osteoporosis are closely related to oxidative stress, which limits the application of nanomaterials in the treatment of osteoporosis.

[0005] Therefore, how to develop nanomaterials with bone targeting, excellent antioxidant properties and the ability to neutralize acidic environments is a technical problem that needs to be urgently solved in this field. Summary of the invention

[0006] The present invention provides a polymer nanoparticle with bone targeting, acidic environment neutralization and antioxidant properties. The polymer nanoparticle is prepared from raw materials including zoledronic acid-modified polycaprolactone-polypeptide copolymers. The polymer nanoparticle has bone targeting, excellent antioxidant properties and the ability to neutralize acidic environments.

[0007] The present invention also provides a preparation method of polymer nanoparticles with bone targeting, acid environment neutralizing and antioxidant properties. Through this preparation method, polymer nanoparticles with bone targeting, excellent antioxidant properties and the ability to neutralize acid environment can be prepared. The preparation process is simple and the preparation period is short, which can be widely promoted and applied.

[0008] The present invention also provides a bone targeting polymer, which is the above-mentioned zoledronic acid modified polycaprolactone - poly-polypeptide copolymer. Using this bone targeting polymer, polymer nanoparticles with bone targeting, excellent antioxidant properties and the ability to neutralize acid environment can be prepared.

[0009] In the first aspect of the present invention, there is provided a polymer nanoparticle with bone targeting, acid environment neutralizing and antioxidant properties. The raw materials for preparing the polymer nanoparticle include zoledronic acid modified polycaprolactone - poly-polypeptide copolymer.

[0010] The chemical structural formula of the zoledronic acid modified polycaprolactone - poly-polypeptide copolymer is shown in formula (1):

[0011]

[0012] For the polymer nanoparticle with bone targeting, acid environment neutralizing and antioxidant properties as described above, the raw materials for preparation further include polycaprolactone - polyethylene oxide.

[0013] For the polymer nanoparticle with bone targeting, acid environment neutralizing and antioxidant properties as described above, in the polymer nanoparticle, the mass ratio of the zoledronic acid modified polycaprolactone - poly-polypeptide copolymer to polycaprolactone - polyethylene oxide is (1 - 3):(0 - 1).

[0014] In the second aspect of the present invention, there is provided a preparation method of the above-mentioned polymer nanoparticle with bone targeting, acid environment neutralizing and antioxidant properties, including the following steps:

[0015] Preparation of zoledronic acid modified polycaprolactone - poly-polypeptide copolymer:

[0016] Dissolve the first raw material system including polycaprolactone, tyrosine cyclic anhydride and Nε - carbobenzoxy - L - lysine cyclic anhydride in the first organic solvent, carry out the first reaction under vacuum, and precipitate the first product after the first reaction with the second organic solvent to obtain polycaprolactone - poly-polypeptide copolymer.

[0017] Dissolve the polycaprolactone - poly-polypeptide copolymer in the third organic solvent for the second reaction, and successively carry out neutralization treatment and the first dialysis treatment on the second product after the second reaction to obtain polycaprolactone - poly-polypeptide copolymer with carbobenzoxy removed.

[0018] Dissolve the polycaprolactone - poly - polypeptide copolymer with the carbobenzoxy group removed in a fourth organic solvent, then add zoledronic acid activated by N,N'-carbonyldiimidazole for a third reaction. Perform a second dialysis treatment on the third product after the third reaction to obtain the zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer;

[0019] Preparation of polymer nanoparticles:

[0020] Dissolve a third raw material system including the zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer and polycaprolactone - polyethylene oxide in a fifth organic solvent to obtain a solution containing the zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer. Add first deionized water to the solution containing the zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer under vigorous stirring for a third dialysis treatment to obtain the polymer nanoparticles.

[0021] The preparation method of the polymer nanoparticles with bone targeting, acid - environment neutralizing and antioxidant properties as described above, wherein the molar ratio of the polycaprolactone, the tyrosine cyclic anhydride and the Nε - carbobenzoxy - L - lysine cyclic anhydride is 1:(0.1 - 30):(0.1 - 15).

[0022] The preparation method of the polymer nanoparticles with bone targeting, acid - environment neutralizing and antioxidant properties as described above, wherein the molar ratio of the polycaprolactone to the zoledronic acid activated by N,N'-carbonyldiimidazole is 1:(0.1 - 10).

[0023] The preparation method of the polymer nanoparticles with bone targeting, acid - environment neutralizing and antioxidant properties as described above. Perform a neutralization treatment and a first dialysis treatment on the second product after the second reaction in sequence, including: neutralize the second product after the second reaction with a sixth organic solvent, and then perform a first dialysis treatment on the neutralized second product with second deionized water for 4h - 100h. The sixth organic solvent is at least one of n - hexane, triethylamine, acetone, ether, ethyl acetate.

[0024] The preparation method of the polymer nanoparticles with bone targeting, acid - environment neutralizing and antioxidant properties as described above. Perform a second dialysis treatment on the third product after the third reaction, including: perform a second dialysis treatment on the third product after the third reaction with third deionized water for 4h - 100h.

[0025] The preparation method of the polymer nanoparticles with bone targeting, acid - environment neutralizing and antioxidant properties as described above, wherein the volume ratio of the fifth organic solvent to the first deionized water is 1:(1 - 5);

[0026] And / or, the time of the third dialysis treatment is 4h - 100h.

[0027] The third aspect of the present invention provides a bone-targeting polymer, which is the above-mentioned zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer.

[0028] The present invention provides a polymer nanoparticle with bone targeting, acid environment neutralization, and antioxidant properties. The raw materials for preparing the polymer nanoparticle include a zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer. The polymer nanoparticle prepared from the zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer as a raw material has bone targeting, excellent antioxidant performance, and the ability to neutralize the acid environment. First, the zoledronic acid in the polymer nanoparticle can bind to hydroxyapatite (the main component of bone) to achieve bone targeting; second, the polytyrosine segment in the polymer nanoparticle can effectively scavenge reactive oxygen species, so the polymer nanoparticle has excellent antioxidant performance; third, the polylysine segment (basic) in the polymer nanoparticle can neutralize the acid environment, so the polymer nanoparticle has the ability to neutralize the acid environment. In addition, the polymer nanoparticle can exert a significant therapeutic effect on osteoporosis (antioxidant, acid environment neutralization) only relying on the intrinsic activity of its own materials, thus fundamentally greatly reducing a series of toxicity problems that may be caused by traditional drugs, and providing a new solution for the treatment of osteoporosis. Brief Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 1H NMR spectrum of polycaprolactone-polyethylene oxide in Example 1 of the present invention;

[0031] Figure 2 1H NMR spectrum of the polycaprolactone-poly-polypeptide copolymer with the carbobenzoxy group removed in Example 1 of the present invention;

[0032] Figure 3 1H NMR spectrum of the zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer in Example 1 of the present invention;

[0033] Figure 4 31P NMR spectrum of the zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer in Example 1 of the present invention;

[0034] Figure 5It is a graph showing the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention;

[0035] Figure 6 It is a graph showing the test results of transmission electron microscopy (TEM) of the polymer nanoparticles in Example 1, Example 2 and Comparative Example 2 of the present invention;

[0036] Figure 7 It is a graph showing the test results of the ability of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention to neutralize acidic environments respectively;

[0037] Figure 8 It is a graph showing the test results of the binding efficiency of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention to hydroxyapatite respectively;

[0038] Figure 9 It is a graph showing the test results of the antioxidant effects of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention respectively; among them, Figure 9 A is a graph showing the test results of the ABTS scavenging efficiency, Figure 9 B is a graph showing the test results of the superoxide anion scavenging efficiency, Figure 9 C is a graph showing the test results of the hydroxyl radical scavenging efficiency;

[0039] Figure 10 It is a graph showing the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention after being diluted 20 times with deionized water;

[0040] Figure 11 It is a graph showing the relationship between the particle size and particle size distribution (PDI) and the polydispersity coefficient of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention under the pH = 4 environment, where, Figure 11 A is a graph showing the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention under the pH = 4 environment, Figure 11 B is the polydispersity coefficient of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention under the pH = 4 environment;

[0041] Figure 12 It is a graph showing the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention under the environment of 10% fetal bovine serum by mass fraction, where, Figure 12 A is a graph showing the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention under the environment of 10% fetal bovine serum by mass fraction, Figure 12B in Examples 1-4 and Comparative Examples 1-2 of the present invention is the polydispersity index of the polymer nanoparticles in an environment of 10% fetal bovine serum by mass fraction. Detailed implementation manners

[0042] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0043] In the embodiments of the present invention, if no specific technology or conditions are indicated, the technology or conditions described in the literature in the field or the product specification shall be followed. The raw materials, reagents or instruments used without indicating the manufacturer can all be conventional products obtained through commercial purchase.

[0044] It should be noted that the descriptions involving "first", "second", "third", "fourth", "fifth", "sixth", etc. in the present invention are used to distinguish similar objects, rather than to describe a specific order or sequence, and therefore should not be construed as a limitation of the present invention.

[0045] The first aspect of the present invention provides a polymer nanoparticle with bone targeting, neutralizing acidic environment and antioxidant properties. The raw materials for preparing the polymer nanoparticle include a zoledronic acid-modified polycaprolactone-poly polypeptide copolymer;

[0046] The chemical structural formula of the zoledronic acid-modified polycaprolactone-poly polypeptide copolymer is shown in Formula (1):

[0047]

[0048] The zoledronic acid-modified polycaprolactone-poly polypeptide copolymer of the present invention is prepared through the following process: reacting a raw material system including polycaprolactone, tyrosine cyclic anhydride and Nε-benzyloxycarbonyl-L-lysine cyclic anhydride, and then using N,N'-carbonyldiimidazole-activated zoledronic acid to modify the reaction product to form a zoledronic acid-modified polycaprolactone-poly polypeptide copolymer.

[0049] The polymeric nanoparticles provided by the present invention are prepared from raw materials including the above-mentioned polycaprolactone - poly-polypeptide copolymer modified with zoledronic acid. The polymeric nanoparticles have bone targeting and excellent antioxidant properties; and the polymeric nanoparticles also have the ability to neutralize acidic environments, and they can neutralize acidic environments to neutrality, maintaining the pH at a normal level. The inventors analyzed this and believed that the reason might be as follows: The zoledronic acid in the polymeric nanoparticles can bind to hydroxyapatite (the main component of bone) to achieve bone targeting. At the same time, the polylysine segment (alkaline) in the polymeric nanoparticles can neutralize acidic environments, and the polytyrosine segment in the polymeric nanoparticles can effectively scavenge reactive oxygen species. Therefore, the polymeric nanoparticles have bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments.

[0050] In another specific embodiment, the raw materials for preparing the above-mentioned polymeric nanoparticles include a polycaprolactone - poly-polypeptide copolymer modified with zoledronic acid and polycaprolactone - polyethylene oxide.

[0051] The polymeric nanoparticles provided by the present invention can also be prepared from raw materials including the above-mentioned polycaprolactone - poly-polypeptide copolymer modified with zoledronic acid and polycaprolactone - polyethylene oxide. The polymeric nanoparticles also have bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments.

[0052] In some embodiments, the preparation method of the above-mentioned polycaprolactone - polyethylene oxide includes the following steps:

[0053] Dissolve methoxypolyethylene glycol and ε-caprolactone in toluene to obtain a mixture solution;

[0054] Heat the mixture solution to 130°C - 140°C to obtain a reaction solution; lower the temperature of the reaction solution from 140°C to room temperature, then add stannous zincate, and immediately heat to 105°C - 120°C for reaction for 24h - 50h. After cooling to room temperature, obtain a reaction product; precipitate, filter by suction, and dry the reaction product in sequence to obtain polycaprolactone - polyethylene oxide.

[0055] In a specific embodiment, in the above-mentioned polymeric nanoparticles, the mass ratio of the polycaprolactone - poly-polypeptide copolymer modified with zoledronic acid to polycaprolactone - polyethylene oxide is (1 - 3):(0 - 1).

[0056] When the mass ratio of the polycaprolactone - poly-polypeptide copolymer modified with zoledronic acid to polycaprolactone - polyethylene oxide in the polymeric nanoparticles is within the above range, polymeric nanoparticles with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments can be prepared.

[0057] Exemplarily, in the polymeric nanoparticles, the mass ratio of the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer to polycaprolactone-poly(ethylene oxide) can be any one of 1:0, 1:1, 2:0, 2:1, 3:0, 3:1 or the range composed of any two of them.

[0058] The second aspect of the present invention provides a method for preparing the above polymeric nanoparticles with bone targeting, acid environment neutralizing and antioxidant properties, comprising the following steps:

[0059] Preparation of the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer:

[0060] Dissolve a first raw material system including polycaprolactone, tyrosine N-carboxyanhydride and Nε-benzyloxycarbonyl-L-lysine N-carboxyanhydride in a first organic solvent, conduct a first reaction under vacuum, and precipitate the first product after the first reaction with a second organic solvent to obtain a polycaprolactone-poly(peptide) copolymer;

[0061] Dissolve the polycaprolactone-poly(peptide) copolymer in a third organic solvent for a second reaction, and successively conduct a neutralization treatment and a first dialysis treatment on the second product after the second reaction to obtain a polycaprolactone-poly(peptide) copolymer with the benzyloxycarbonyl group removed;

[0062] Dissolve the polycaprolactone-poly(peptide) copolymer with the benzyloxycarbonyl group removed in a fourth organic solvent, then add N,N'-carbonyldiimidazole-activated zoledronic acid for a third reaction, and conduct a second dialysis treatment on the third product after the third reaction to obtain the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer;

[0063] Preparation of the polymeric nanoparticles:

[0064] Dissolve a third raw material system including the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer and polycaprolactone-poly(ethylene oxide) in a fifth organic solvent to obtain a solution containing the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer. Under vigorous stirring, add first deionized water to the solution containing the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer for a third dialysis treatment to obtain the polymeric nanoparticles.

[0065] Specifically, in the present invention, a first raw material system including polycaprolactone, tyrosine cyclic anhydride, and Nε-carbobenzoxy-L-lysine cyclic anhydride is first dissolved in a first organic solvent, and a first reaction is carried out under vacuum to obtain a first product. Then, the first product is subjected to precipitation treatment with a second organic solvent to obtain a polycaprolactone-poly-polypeptide copolymer. The precipitation treatment is to effectively separate the polycaprolactone-poly-polypeptide copolymer from the organic solvent. Then, the polycaprolactone-poly-polypeptide copolymer is dissolved in a third organic solvent for a second reaction to obtain a second product, and then the second product is subjected to neutralization treatment to obtain the second product after neutralization treatment. The second reaction is to remove the carbobenzoxy group to facilitate the subsequent modification with zoledronic acid. Subsequently, the second product after neutralization treatment is subjected to a first dialysis treatment to obtain a polycaprolactone-poly-polypeptide copolymer with the carbobenzoxy group removed. The first dialysis treatment is to remove the organic solvent in the second product after neutralization treatment. The polycaprolactone-poly-polypeptide copolymer with the carbobenzoxy group removed is dissolved in a fourth organic solvent, and then N,N'-carbonyldiimidazole-activated zoledronic acid is added for a third reaction to obtain a third product. The third product is subjected to a second dialysis treatment to obtain a zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer. The second dialysis treatment is to remove the organic solvent in the third product. Then, a third raw material system including the zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer and polycaprolactone-poly-ethylene oxide is dissolved in a fifth organic solvent to obtain a mixed solution containing the zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer and polycaprolactone-poly-ethylene oxide. Under vigorous stirring, first deionized water is added to the mixed solution containing the zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer and polycaprolactone-poly-ethylene oxide for a third dialysis treatment to prepare a polymeric nanoparticle with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments. The third dialysis treatment is to remove the organic solvent in the nanoparticle dispersion formed by the mixed solution of the zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer and polycaprolactone-poly-ethylene oxide to obtain a polymeric nanoparticle with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments.

[0066] In the present invention, N,N'-carbonyldiimidazole-activated zoledronic acid is prepared through the following process:

[0067] Zoledronic acid is dissolved in anhydrous dimethyl sulfoxide, and then triethylamine is added to obtain a mixture. The mixture is degassed with nitrogen, and then N,N'-carbonyldiimidazole is added for reaction under nitrogen protection. Then, the product obtained after the reaction is precipitated in acetone, the supernatant is removed by centrifugation, and it is dried under vacuum to obtain N,N'-carbonyldiimidazole-activated zoledronic acid.

[0068] The present invention does not make specific limitations on the specific sources of the above raw materials, and they can be obtained through commercial channels.

[0069] The present invention does not particularly limit the specific amounts of the above organic solvents, which can be selected according to specific needs.

[0070] Through the above preparation method, the present invention can prepare polymer nanoparticles with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments. This preparation method has a simple process and a short preparation cycle, and can be widely promoted and applied.

[0071] In a specific embodiment, the molar ratio of the above polycaprolactone, tyrosine cyclic anhydride, and Nε-carbobenzoxy-L-lysine cyclic anhydride is 1:(0.1 - 30):(0.1 - 15).

[0072] When the molar ratio of polycaprolactone, tyrosine cyclic anhydride, and Nε-carbobenzoxy-L-lysine cyclic anhydride is within the above range, the first reaction can proceed sufficiently, which is beneficial to the preparation of polycaprolactone-poly polypeptide copolymer.

[0073] In a specific embodiment, the molar ratio of the above polycaprolactone to zoledronic acid activated by N,N'-carbonyldiimidazole is 1:(0.1 - 10).

[0074] When the molar ratio of polycaprolactone to zoledronic acid activated by N,N'-carbonyldiimidazole is within the above range, the third reaction can proceed sufficiently, which is beneficial to the preparation of zoledronic acid-modified polycaprolactone-poly polypeptide copolymer.

[0075] In a specific embodiment, the second product after the second reaction is successively subjected to neutralization treatment and first dialysis treatment, including: neutralizing the second product after the second reaction with a sixth organic solvent, and then performing first dialysis treatment on the neutralized second product with second deionized water for 4h - 100h. The sixth organic solvent is at least one of n-hexane, triethylamine, acetone, diethyl ether, and ethyl acetate.

[0076] The present invention does not particularly limit the specific amounts of the sixth organic solvent and the second deionized water, which can be selected according to needs.

[0077] By using the above sixth organic solvent to neutralize the second product after the second reaction, the present invention can more effectively remove the carbobenzoxy group to facilitate subsequent modification with zoledronic acid; then, by performing first dialysis treatment on the neutralized second product with second deionized water, the organic solvents in the neutralized second product can be removed, thereby preparing a polycaprolactone-poly polypeptide copolymer with the carbobenzoxy group removed, which is beneficial to the subsequent preparation of polymer nanoparticles with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments.

[0078] In a specific embodiment, the second dialysis treatment of the third product after the third reaction includes: performing the second dialysis treatment on the third product after the third reaction with third deionized water for 4 h to 100 h.

[0079] The present invention does not particularly limit the specific amount of the third deionized water, and it can be selected according to needs.

[0080] By performing the second dialysis treatment on the third product after the third reaction with third deionized water, the present invention can remove the organic solvent in the third product, thereby preparing a zoledronic acid-modified polycaprolactone-poly polypeptide copolymer, which is beneficial to the subsequent preparation of polymer nanoparticles with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments.

[0081] In a specific embodiment, the volume ratio of the above-mentioned fifth organic solvent to the first deionized water is 1:(1 - 5), and preferably 1:2.

[0082] When the volume ratio of the fifth organic solvent to the first deionized water is 1:2, nanoparticles with the optimal particle size can be assembled.

[0083] In a specific embodiment, the time of the above-mentioned third dialysis treatment is 4 h to 100 h.

[0084] When the time of the third dialysis treatment is within the above range, the organic solvent in the solution containing the zoledronic acid-modified polycaprolactone-poly polypeptide copolymer can be effectively removed, thereby preparing polymer nanoparticles with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments.

[0085] In some embodiments, the time of the above-mentioned first reaction is 4 h to 100 h.

[0086] When the parameter of the time of the first reaction is within the above range, the first reaction can proceed sufficiently, thereby preparing a polycaprolactone-poly polypeptide copolymer.

[0087] In some embodiments, the temperature of the above-mentioned second reaction is 20°C to 30°C, and the time is 1 h to 5 h.

[0088] When the parameters of the temperature and time of the second reaction are within the above range, the second reaction can proceed sufficiently, thereby preparing a polycaprolactone-poly polypeptide copolymer with the carbobenzoxy group removed.

[0089] In some embodiments, the time of the above-mentioned third reaction is 1 h to 15 h.

[0090] When the parameter of the time of the third reaction is within the above range, the third reaction can proceed sufficiently, thereby preparing a zoledronic acid-modified polycaprolactone-poly polypeptide copolymer.

[0091] In some embodiments, the first organic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, hydrobromic acid, trifluoroacetic acid, tetrahydrofuran, and dichloromethane; the second organic solvent is at least one of n-hexane, triethylamine, acetone, diethyl ether, and ethyl acetate; the third organic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, hydrobromic acid, trifluoroacetic acid, tetrahydrofuran, and dichloromethane; the fourth organic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, hydrobromic acid, trifluoroacetic acid, tetrahydrofuran, and dichloromethane; the fifth organic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, hydrobromic acid, trifluoroacetic acid, tetrahydrofuran, and dichloromethane.

[0092] The present invention does not particularly limit the specific sources of the above organic solvents, and they can be obtained commercially.

[0093] The third aspect of the present invention provides a bone-targeting polymer, which is the above-mentioned zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer. The present invention can prepare polymer nanoparticles with bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments by using this bone-targeting polymer.

[0094] Hereinafter, the present invention will be further introduced through specific examples.

[0095] The N-carboxyanhydride of tyrosine used in the following examples was synthesized according to the method in the reference (Antioxidant and Immunomodulatory Polymer Vesicles for Effective Diabetic Wound Treatment through Ros Scavenging and Immune Modulating. Nano Letters 2024, 24, 9494-9504).

[0096] Example 1

[0097] In this example, polymer nanoparticles were obtained through the following preparation method:

[0098] Preparation of zoledronic acid-modified polycaprolactone-poly-polypeptide copolymer:

[0099] (1) Dissolve 1.164 g of polycaprolactone and 2 g of N-carboxyanhydride of tyrosine in 6 mL of ultra-dry N,N-dimethylformamide and react under vacuum for 24 h. Then add 1.267 g of Nε-benzyloxycarbonyl-L-lysine N-carboxyanhydride and continue to react for 24 h to obtain a first product. Precipitate the first product with diethyl ether to obtain a polycaprolactone-poly-polypeptide copolymer;

[0100] (2) Dissolve 1 g of polycaprolactone - polypeptid copolymer in 30 mL of trifluoroacetic acid, then add 10 mL of hydrobromic acid acetic acid solution to obtain a mixture. React the mixture at 25 °C for 4 h to obtain a second product. Neutralize the second product with 40 mL of triethylamine to obtain the neutralized second product, and then dialyze the neutralized second product with deionized water for 48 h to obtain the polycaprolactone - polypeptid copolymer with benzyloxycarbonyl removed; the chemical structural formula of the polycaprolactone - polypeptid copolymer with benzyloxycarbonyl removed is as follows:

[0101]

[0102] (3) Dissolve 100 mg of zoledronic acid in 50 mL of anhydrous dimethyl sulfoxide, then add 2 mL of triethylamine to obtain a mixture; degas the mixture with nitrogen for 30 minutes, then add N,N'-carbonyldiimidazole under nitrogen protection and react at 60 °C for 24 h. Then precipitate the product obtained after the reaction three times in acetone, centrifuge to remove the supernatant, and dry under vacuum for 24 h to obtain N,N'-carbonyldiimidazole-activated zoledronic acid;

[0103] (4) Dissolve 0.23 g of the polycaprolactone - polypeptid copolymer with benzyloxycarbonyl removed in 2 mL of ultradry dimethyl sulfoxide, then add 0.23 mL of triethylamine to obtain a mixture solution. After purging nitrogen into the mixture solution for 30 min, add 0.07 g of N,N'-carbonyldiimidazole-activated zoledronic acid to the mixture solution, place it in a closed reactor and react for 12 h to obtain a third product. Dialyze the third product with deionized water for 48 h to obtain the zoledronic acid-modified polycaprolactone - polypeptid copolymer; the chemical structural formula of the zoledronic acid-modified polycaprolactone - polypeptid copolymer is as follows:

[0104]

[0105] Preparation of polymer nanoparticles:

[0106] (1) Dissolve 5 mg of the zoledronic acid-modified polycaprolactone - polypeptid copolymer in 4 mL of dimethyl sulfoxide to obtain a solution containing the zoledronic acid-modified polycaprolactone - polypeptid copolymer. Under vigorous stirring, add 8 mL of deionized water dropwise to the solution containing the zoledronic acid-modified polycaprolactone - polypeptid copolymer at a rate of 20 drops / min (drops per minute) and perform dialysis for 48 h to remove dimethyl sulfoxide to obtain polymer nanoparticles.

[0107] Example 2

[0108] The preparation method of the polymer nanoparticles provided in this example is basically the same as that in Example 1, except that:

[0109] Preparation of polymer nanoparticles:

[0110] (1) Preparation of polycaprolactone - polyethylene oxide:

[0111] Dissolve 1.00 g of methoxypolyethylene glycol (CAS: 9004 - 74 - 4) and 4.56 g of ε - caprolactone in 75 mL of toluene to obtain a mixture solution. Heat the mixture solution to 140 °C to remove water by azeotropic distillation until the toluene in the mixture solution is 12 mL to obtain a reaction solution. Cool the temperature of the reaction solution from 140 °C to room temperature, purge the reaction solution with argon for 30 min to remove oxygen, then add 0.0094 g of stannous zincate with a pipette under argon protection, and further purge with argon for 15 min. Immediately heat to 110 °C and react for 48 h. After cooling to room temperature, obtain a reaction product. Precipitate the reaction product three times repeatedly in n - hexane, filter by suction to obtain a white powder, place the white powder in a vacuum oven at 30 °C and dry for 48 hours to finally obtain white powder - like polycaprolactone - polyethylene oxide (1H NMR spectrum as shown in Figure 1 shown), and the chemical structure of polycaprolactone - polyethylene oxide is as follows:

[0112]

[0113] (2) Dissolve 1 mg of zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer and 1 mg of polycaprolactone - polyethylene oxide in 4 mL of dimethyl sulfoxide to obtain a solution containing zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer. Under vigorous stirring, add 8 mL of deionized water drop - wise to the solution containing zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer at a rate of 20 drops / min (drops per minute) and carry out dialysis treatment for 48 h to remove dimethyl sulfoxide to obtain polymer nanoparticles.

[0114] Example 3

[0115] The method for preparing the polymer nanoparticles provided in this example is basically the same as that in Example 2, except that:

[0116] Preparation of polymer nanoparticles:

[0117] (2) Dissolve 1 mg of zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer and 0.5 mg of polycaprolactone - polyethylene oxide in 4 mL of dimethyl sulfoxide to obtain a solution containing zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer. Under vigorous stirring, add 8 mL of deionized water drop - wise to the solution containing zoledronic acid - modified polycaprolactone - poly - polypeptide copolymer at a rate of 20 drops / min (drops per minute) and carry out dialysis treatment for 48 h to remove dimethyl sulfoxide to obtain polymer nanoparticles.

[0118] Example 4

[0119] The preparation method of the polymer nanoparticles provided in this example is basically the same as that in Example 2, except that:

[0120] Preparation of polymer nanoparticles:

[0121] (2) Dissolve 1.2 mg of zoledronic acid-modified polycaprolactone-poly(peptide) copolymer and 0.4 mg of polycaprolactone-poly(ethylene oxide) in 4 mL of dimethyl sulfoxide to obtain a solution containing the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer. Under vigorous stirring, add 8 mL of deionized water dropwise to the solution containing the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer at a rate of 20 drops / min (drops per minute) for dialysis treatment for 48 h to remove dimethyl sulfoxide, thereby obtaining polymer nanoparticles.

[0122] Comparative Example 1

[0123] The preparation method of the polymer nanoparticles provided in this comparative example is basically the same as that in Example 2, except that:

[0124] Preparation of polymer nanoparticles:

[0125] (2) Dissolve 0.5 mg of zoledronic acid-modified polycaprolactone-poly(peptide) copolymer and 1 mg of polycaprolactone-poly(ethylene oxide) in 4 mL of dimethyl sulfoxide to obtain a solution containing the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer. Under vigorous stirring, add 8 mL of deionized water dropwise to the solution containing the zoledronic acid-modified polycaprolactone-poly(peptide) copolymer at a rate of 20 drops / min (drops per minute) for dialysis treatment for 48 h to remove dimethyl sulfoxide, thereby obtaining polymer nanoparticles.

[0126] Comparative Example 2

[0127] The polymer nanoparticles in this comparative example were obtained through the following preparation method:

[0128] Dissolve 1 mg of polycaprolactone-poly(ethylene oxide) (prepared according to the method in Example 2 for polycaprolactone-poly(ethylene oxide)) in 4 mL of dimethyl sulfoxide to obtain a solution containing polycaprolactone-poly(ethylene oxide). Under vigorous stirring, add 8 mL of deionized water dropwise to the solution containing polycaprolactone-poly(ethylene oxide) at a rate of 20 drops / min (drops per minute) for dialysis treatment for 48 h to remove dimethyl sulfoxide, thereby obtaining polymer nanoparticles.

[0129] Performance testing

[0130] 1. Proton nuclear magnetic resonance spectroscopy test

[0131] The 1H NMR test was carried out on the polycaprolactone - polypeptid copolymer with the benzyloxycarbonyl group removed in Example 1 of the present invention. The 1H NMR test and 31P NMR test were respectively carried out on the polycaprolactone - polypeptid copolymer modified with zoledronic acid in Example 1 of the present invention. Figure 2 It is the 1H NMR spectrum of the polycaprolactone - polypeptid copolymer with the benzyloxycarbonyl group removed in Example 1 of the present invention; Figure 3 It is the 1H NMR spectrum of the polycaprolactone - polypeptid copolymer modified with zoledronic acid in Example 1 of the present invention; Figure 4 It is the 31P NMR spectrum of the polycaprolactone - polypeptid copolymer modified with zoledronic acid in Example 1 of the present invention.

[0132] From Figures 2 - 4 it can be seen that compared with the 1H NMR spectrum of the polycaprolactone - polypeptid copolymer with the benzyloxycarbonyl group removed, characteristic peaks of zoledronic acid appear at the position of 4.5 - 5.0 ppm in the 1H NMR spectrum of the polycaprolactone - polypeptid copolymer modified with zoledronic acid, and characteristic peaks of zoledronic acid also appear in the 31P NMR spectrum of the polycaprolactone - polypeptid copolymer modified with zoledronic acid, confirming that zoledronic acid (ZOL) has been successfully modified onto the polycaprolactone - polypeptid copolymer with the benzyloxycarbonyl group removed.

[0133] 2. Particle size and particle size distribution (PDI) test

[0134] Figure 5 It is the relationship diagram of the particle size and particle size distribution (PDI) of the polymeric nanoparticles in Examples 1 - 4 and Comparative Examples 1 - 2 of the present invention.

[0135] From Figure 5 it can be seen that the particle size of the polymeric nanoparticles in Example 1 of the present invention is 185 nm, and the particle size distribution is narrow; the particle size of the polymeric nanoparticles in Example 2 is 180 nm, and the particle size distribution is narrow; the particle size of the polymeric nanoparticles in Example 3 is 168 nm, and the particle size distribution is narrow; the particle size of the polymeric nanoparticles in Example 4 is 157 nm, and the particle size distribution is narrow; the particle size of the polymeric nanoparticles in Comparative Example 1 is 200 nm, and the particle size distribution is narrow; the particle size of the polymeric nanoparticles in Comparative Example 2 is 266 nm, and the particle size distribution is narrow.

[0136] 3. Transmission electron microscope (TEM) test

[0137] Figure 6 It is the transmission electron microscope (TEM) test result diagram of the polymeric nanoparticles in Example 1, Example 2 and Comparative Example 2 of the present invention.

[0138] From Figure 6 it can be seen that the structure of the polymeric nanoparticles in Example 2 of the present invention is clear and uniformly dispersed. The vesicle structure helps to improve the stability of the nanomaterials, helps in vivo circulation and improves the bioavailability.

[0139] 4. Test the ability of the polymer nanoparticles to neutralize the acidic environment

[0140] Test the ability of the polymer nanoparticles in Examples 1 - 4 and Comparative Examples 1 - 2 to neutralize the acidic environment respectively. The test results are as Figure 7 shown.

[0141] It can be seen from Figure 7 that the polymer nanoparticles in Examples 1 - 4 of the present invention can effectively neutralize hydrochloric acid aqueous solution in vitro and maintain the pH value at the level of 7.0 - 7.4.

[0142] 5. Test the binding efficiency of the polymer nanoparticles and hydroxyapatite

[0143] Test the binding rate of the polymer nanoparticles in Examples 1 - 4 and Comparative Examples 1 - 2 respectively. The test results are as Figure 8 and Table 1 show;

[0144] Binding rate: Dissolve 5 mg of fluorescein isothiocyanate (FITC) powder in 5 mL of deionized water to obtain a FITC solution. Then assemble the FITC solution with the polymer nanoparticles to obtain polymer vesicles loaded with FITC. Measure the initial fluorescence intensity as I t0 using a fluorescence spectrometer (excitation wavelength = 480 nm, emission wavelength = 560 nm, working voltage = 700 V); then add hydroxyapatite powder (25.0 mg) to 4.00 mL of FITC-labeled polymer vesicles, continuously stir at 37 °C for 3 h, then centrifuge and take the supernatant, and measure the fluorescence intensity of the supernatant as I t ; The formula for calculating the binding rate (HAbinding rate) of the vesicles and hydroxyapatite is as follows:

[0145] Binding rate = (I t0 - I t ) / I t0 × 100%.

[0146] Table 1 Test results

[0147] Item Combination Efficiency (%) Example 1 77.63 Example 2 75.34 Example 3 58.57 Example 4 71.55 Comparative Example 1 52.54 Comparative Example 2 47.23

[0148] It can be seen from Figure 8As can be seen from Table 1, the vesicles of the polymeric nanoparticles in Example 1 of the present invention exhibited the best binding performance, with a binding rate of 77.63%. The vesicles of the polymeric nanoparticles in Example 2 showed a relatively high binding rate, reaching 75.34%, indicating that a mass ratio of 1:1 of zoledronic acid-modified polycaprolactone-poly(peptide) copolymer to polycaprolactone-poly(ethylene oxide) was sufficient to achieve bone targeting, and the addition of polycaprolactone-poly(ethylene oxide) did not significantly affect the bone targeting ability of the mixed corona vesicles. In contrast, the binding rate of the vesicles of the polymeric nanoparticles in Comparative Example 2 to hydroxyapatite was 47.2%, which was attributed to the non-specific adsorption of hydroxyapatite to the vesicles, and this inefficient binding did not represent true bone targeting. The binding of zoledronic acid (ZOL) to hydroxyapatite (HA) was mainly attributed to the strong affinity of ZOL for calcium ions in the HA crystal, and this interaction was further enhanced due to the structural similarity of ZOL to the phosphate groups in hydroxyapatite, resulting in its preferential adsorption on the surface of HA.

[0149] 6. Test the antioxidant performance of the polymeric nanoparticles

[0150] The ABTS scavenging efficiency (%), superoxide anion scavenging efficiency (%), and hydroxyl radical scavenging efficiency (%) of the polymeric nanoparticles in Examples 1 - 4 and Comparative Examples 1 - 2 were tested respectively, and the test results are as Figure 9 shown in Table 2;

[0151] Table 2 Test results

[0152]

[0153]

[0154] As Figure 9 can be seen from Table 2, the ABTS scavenging efficiency, superoxide anion scavenging efficiency, and hydroxyl radical scavenging efficiency of the polymeric nanoparticles in Examples 1 - 4 of the present invention were higher than those of the polymeric nanoparticles in Comparative Examples 1 and 2, indicating that the polymeric nanoparticles provided in the examples of the present invention have excellent antioxidant performance.

[0155] 7. Test the stability of the polymeric nanoparticles

[0156] Figure 10 is the relationship diagram of the particle size and particle size distribution (PDI) of the polymeric nanoparticles in Examples 1 - 4 and Comparative Examples 1 - 2 of the present invention diluted 20 times with deionized water; Figure 11 is the relationship diagram of the particle size and particle size distribution (PDI) and polydispersity coefficient of the polymeric nanoparticles in Examples 1 - 4 and Comparative Examples 1 - 2 of the present invention in an environment with pH = 4, where Figure 11Figure A shows the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention under the condition of pH = 4. Figure 11 Figure B shows the polydispersity index of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention under the condition of pH = 4. Figure 12 Figure A shows the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention in an environment of 10% fetal bovine serum by mass fraction. Among them, Figure 12 Figure A shows the relationship between the particle size and particle size distribution (PDI) of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention in an environment of 10% fetal bovine serum by mass fraction. Figure 12 Figure B shows the polydispersity index of the polymer nanoparticles in Examples 1-4 and Comparative Examples 1-2 of the present invention in an environment of 10% fetal bovine serum by mass fraction.

[0157] It can be seen from Figures 10 - 12 that the polymer nanoparticles provided by the present invention have good water solubility and dispersibility, and have good stability both in pH = 4 and serum storage, with a long storage time, uniform dispersion, and are not easy to agglomerate, ensuring the safety of in vivo application.

[0158] In summary, the polymer nanoparticles prepared in the examples of the present invention have bone targeting, excellent antioxidant properties, and the ability to neutralize acidic environments.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polymer nanoparticle having bone targeting, neutralizing acidic environment and anti-oxidation properties, characterized in that: The raw materials for preparing the polymer nanoparticles include zoledronic acid-modified polycaprolactone-polypeptide copolymer; The chemical structure of the zoledronic acid modified polycaprolactone-polypolypeptide copolymer is shown in formula (1):

2. The polymer nanoparticles having bone targeting, acid neutralization and antioxidant properties according to claim 1, characterized in that: The preparation raw materials also include polycaprolactone-polyethylene oxide.

3. The polymer nanoparticles having bone targeting, acid neutralization and antioxidant properties according to claim 2, characterized in that: In the polymer nanoparticles, the mass ratio of the zoledronic acid-modified polycaprolactone-polypolypeptide copolymer to polycaprolactone-polyethylene oxide is (1-3): (0-1).

4. A method for preparing polymer nanoparticles having bone targeting, acid neutralization and antioxidant properties as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: Preparation of zoledronic acid modified polycaprolactone-polypeptide copolymer: Dissolving a first raw material system including polycaprolactone, tyrosine cyclic anhydride and Nε-benzyloxycarbonyl-L-lysine cyclic anhydride in a first organic solvent, performing a first reaction under vacuum, and precipitating a first product after the first reaction using a second organic solvent to obtain a polycaprolactone-polypeptide copolymer; dissolving the polycaprolactone-polypolypeptide copolymer in a third organic solvent for a second reaction, and sequentially performing a neutralization treatment and a first dialysis treatment on a second product after the second reaction to obtain a polycaprolactone-polypolypeptide copolymer from which the benzyloxycarbonyl group has been removed; The polycaprolactone-polypeptide copolymer from which the benzyloxycarbonyl group has been removed is dissolved in a fourth organic solvent, and then zoledronic acid activated by N,N'-carbonyldiimidazole is added to perform a third reaction, and the third product after the third reaction is subjected to a second dialysis treatment to obtain the polycaprolactone-polypeptide copolymer modified with zoledronic acid; Preparation of polymer nanoparticles: The third raw material system including the zoledronic acid modified polycaprolactone-polypolypeptide copolymer and polycaprolactone-polyethylene oxide is dissolved in a fifth organic solvent to obtain a solution containing the zoledronic acid modified polycaprolactone-polypolypeptide copolymer, and the first deionized water is added to the solution containing the zoledronic acid modified polycaprolactone-polypolypeptide copolymer under vigorous stirring to perform a third dialysis treatment to obtain the polymer nanoparticles.

5. The method for preparing polymer nanoparticles having bone targeting, neutralizing acidic environment and anti-oxidation properties according to claim 4, characterized in that: The molar ratio of the polycaprolactone, the tyrosine cyclic anhydride and the Nε-benzyloxycarbonyl-L-lysine cyclic anhydride is 1:(0.1-30):(0.1-15).

6. The method for preparing polymer nanoparticles having bone targeting, acid neutralization and antioxidant properties according to claim 4, characterized in that: The molar ratio of the polycaprolactone to the N,N'-carbonyldiimidazole activated zoledronic acid is 1:(0.1-10).

7. The method for preparing polymer nanoparticles having bone targeting, acid neutralization and antioxidant properties according to claim 4, characterized in that: The second product after the second reaction is subjected to a neutralization treatment and a first dialysis treatment in sequence, including: neutralizing the second product after the second reaction with a sixth organic solvent, and then performing a first dialysis treatment on the neutralized second product with a second deionized water for 4 hours to 100 hours, wherein the sixth organic solvent is at least one of n-hexane, triethylamine, acetone, ether, and ethyl acetate.

8. The method for preparing polymer nanoparticles having bone targeting, acid neutralization and antioxidant properties according to claim 4, characterized in that: The third product after the third reaction is subjected to a second dialysis treatment, comprising: using a third deionized water to perform a second dialysis treatment on the third product after the third reaction for 4 hours to 100 hours.

9. The method for preparing polymer nanoparticles having bone targeting, acid neutralization and antioxidant properties according to claim 4, characterized in that: The volume ratio of the fifth organic solvent to the first deionized water is 1:(1-5); And / or, the third dialysis treatment duration is 4 h to 100 h.

10. A bone-targeting polymer, characterized in that: The bone-targeting polymer is the zoledronic acid-modified polycaprolactone-polypolypeptide copolymer as described in claim 1.

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