Polycamptothecin nanomedicine, preparation method and use thereof

Abstract

This invention relates to polycamptothecin nanomedicines, their preparation methods, and applications, belonging to the field of antitumor drug technology. The polycamptothecin nanomedicines are nanomedicines formed by the self-assembly of the amphiphilic block polymer polysarcosine-b-polycamptothecin glutamate. Polysarcosine-b-polycamptothecin glutamate can be synthesized through a two-step ring-opening polymerization method, and further, through a solvent removal method, the polymer can be driven to self-assemble into polycamptothecin nanomedicines. The size of these polycamptothecin nanomedicines is approximately 200 nm, with a drug loading as high as 34.4%. The polycamptothecin nanomedicines of this invention exhibit good biocompatibility, precisely releasing camptothecin with anticancer activity only under the reducing action of glutathione, achieving precise tumor treatment.

Description

Technical Field

[0001] This invention relates to a polycamptothecin nanomedicine, its preparation method and uses, which can be used for efficient loading and controlled release of camptothecin. Background Technology

[0002] Camptothecin, a natural quinoline alkaloid that inhibits DNA topoisomerase, was discovered and approved for use as an anticancer drug as early as 1966. However, camptothecin has extremely poor water solubility, dissolving only in trace amounts of organic solvents such as dimethyl sulfoxide, and it also has certain adverse drug reactions, greatly limiting its use. To address these issues, scientists have developed various camptothecin derivatives, such as topotecan and irinotecan, to enhance its efficacy and reduce adverse reactions.

[0003] It is worth mentioning that advanced nanotechnology can effectively improve drug solubility and targeting, enhance therapeutic efficacy, and reduce drug toxicity. In particular, polyamino acid materials possess excellent biocompatibility, are easy to synthesize and functionalize, and are widely used in the design and construction of efficient drug delivery systems. Functional polyamino acid materials can be conveniently and rapidly synthesized using the mild ring-opening polymerization reaction of N-carboxylic anhydrides (NCA). Through pre-polymerization or polymer functionalization, drug molecules can be effectively loaded onto polyamino acid polymer chains, thereby self-assembling to form nanomedicines.

[0004] Most of the currently reported nanomedicines loaded with camptothecin use polyethylene glycol for surface modification, which greatly limits their application. Summary of the Invention

[0005] The purpose of this invention is to provide a polycamptothecin nanomedicine, its preparation method, and its uses, for the efficient loading and delivery of camptothecin, improving the efficacy of camptothecin and reducing its toxic side effects. The polycamptothecin nanomedicine of this invention has a uniform morphology and a size of approximately 200 nm. The polycamptothecin nanomedicine of this invention has a drug loading capacity as high as 34.4%, while effectively preventing drug leakage. The polycamptothecin nanomedicine of this invention has a simple preparation method, and the drug loading capacity can be effectively controlled by adjusting the polymer structure. It also exhibits controlled release characteristics within the tumor microenvironment, resulting in significant in vivo and in vitro biological effects.

[0006] To solve the technical problem of this invention, the proposed technical solution is as follows: a polycamptothecin nanomedicine, which is a nanomedicine formed by the self-assembly of the amphiphilic block polymer polysarcosine-b-polyglutamic acid camptothecin ester (PSar-b-PCPTG), wherein the PSar-b-PCPTG has the following structure:

[0007]

[0008] Preferably, the polycamptothecin nanomedicine is in the form of a uniform sphere with a size of 200 nm and a camptothecin loading of 34.4%.

[0009] To solve the technical problem of this invention, another technical solution is proposed as follows: The preparation method of the polycamptothecin nanomedicine includes the following steps:

[0010] Step 1: Synthesis of disulfide-modified camptothecin (CPT-SS-OH)

[0011] Weigh 348 mg of camptothecin into a Schlenk flask, add 780 mg of 4-dimethylaminopyridine, purge with argon three times, and add 80 mL of freshly distilled dichloromethane; then add 20 mL of anhydrous dichloromethane solution containing 200 mg of triphosgene, stir at room temperature in the dark for 3 h, add 10 mL of tetrahydrofuran solution containing 771 mg of 2-hydroxyethyl disulfide, and stir overnight at room temperature in the dark; then dilute with an appropriate amount of anhydrous dichloromethane, wash three times with hydrochloric acid (pH 1.0), twice with saturated sodium chloride aqueous solution, and once with deionized water, and dry with anhydrous sodium sulfate; filter, rotary evaporate, and purify by column chromatography, with the eluent being dichloromethane:methanol = 50:1; remove the organic solvent by rotary evaporation to obtain a pale yellow solid with a yield of approximately 70%;

[0012] Step 2: Synthesis of Boc-Glutamic Acid Camptothecin Ester (Boc-Glu-SS-CPT)

[0013] 792 mg of CPT-SS-OH was dispersed in 150 mL of anhydrous dichloromethane. 463.5 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 675 mg of Boc-L-glutamic acid-1-tert-butyl ester, and 184 mg of 4-dimethylaminopyridine were added sequentially. The mixture was initially stirred in an ice-water bath, then stirred overnight at room temperature in the dark. The organic phase was washed three times with saturated ammonium bicarbonate solution, saturated sodium chloride solution, and deionized water, dried without magnesium sulfate, and purified by column chromatography using dichloromethane to dichloromethane:methanol = 50:1 as the mobile phase. The organic solvent was removed by rotary evaporation to obtain a pale yellow solid with a yield of approximately 77%.

[0014] Step 3: Synthesis of Camptothecin Glutamate (Glu-SS-CPT)

[0015] 813 mg of Boc-Glu-SS-CPT was dissolved in 5 mL of anhydrous dichloromethane, and an equal volume of trifluoroacetic acid was added. The mixture was stirred for 1.5 h in an ice-water bath. The organic solvent was then rotary evaporated, and the solid was dissolved in a small amount of dichloromethane. The reaction was repeated twice, and the solid was finally precipitated in anhydrous diethyl ether and dried under vacuum to obtain a pale yellow solid with a yield of approximately 86%.

[0016] Step 4: Synthesis of Camptothecin-N-carboxylic anhydride (CPT-NCA)

[0017] 300 mg of Glu-SS-CPT was suspended in 45 mL of freshly distilled tetrahydrofuran, and then 162 mg of triphosgene was added. The mixture was heated to 56 °C and reacted until the solution was clear. The solution was concentrated under vacuum, and then 20 mL of tetrahydrofuran was added. The solution was precipitated in 40 mL of anhydrous n-hexane. The precipitate was washed three times with tetrahydrofuran:n-hexane = 1:2 (v / v) and dried in a vacuum drying oven. The yield was approximately 50%.

[0018] Step 5: Synthesis of polyglutamic acid camptothecin ester (PCPTG)

[0019] The 25 mL Schlenk flask was purged with argon three times, 412 mg of CPT-NCA was added, and the flask was purged with argon three more times. Then, 5 mL of freshly distilled dichloromethane and 3.0 mg of hexylamine were added. The mixture was reacted under argon protection for 12 h, and anhydrous diethyl ether precipitate was obtained. The precipitate was then dried under vacuum. Finally, the obtained polymer was stored in a refrigerator at 2-8 °C.

[0020] Step 6: Synthesis of polysarcosine-β-polycamptothecin glutamate (PSar-β-PCPTG)

[0021] 115 mg of sarcosine-N-carboxylic anhydride was placed in a Schlenk flask, purged with argon three times, and 2 mL of anhydrous dichloromethane was added. Then, 1 mL of anhydrous dichloromethane solution containing 128 mg of PCPTG was rapidly injected into the Schlenk flask. The reaction was then carried out under an argon atmosphere for 24 h. After the reaction was completed, the precipitate was collected in anhydrous diethyl ether and dried under vacuum.

[0022] Step 7: Preparation of Polycamptothecin Nanomedicine (PSar-b-PCPTG NPs)

[0023] 10 mg of PSar-b-PCPTG was dissolved in 1 mL of dimethyl sulfoxide, and then 9 mL of deionized water was slowly added dropwise at a rate of 8 mL / h. After the addition was complete, the solution was dialyzed to remove the organic solvent. The solution was then lyophilized to obtain PSar-b-PCPTG NPs.

[0024] The preferred reaction route is as follows:

[0025]

[0026] To solve the technical problem of this invention, another technical solution is proposed as follows: the application of the polycamptothecin nanomedicine, wherein the polycamptothecin nanomedicine can achieve efficient loading of camptothecin; the polycamptothecin nanomedicine can effectively avoid the leakage of camptothecin, and under the reducing conditions of glutathione, achieve precise and rapid release of camptothecin, effectively inhibiting the growth of tumor cells.

[0027] Beneficial effects:

[0028] The polycamptothecin nanomedicine of the present invention has a uniform morphology and a size of about 200 nm.

[0029] The polycamptothecin nanomedicine of the present invention has good biocompatibility and a drug loading capacity of up to 34.4%, while effectively preventing drug leakage.

[0030] The polycamptothecin nanomedicine of the present invention has a simple and easy preparation method. By regulating the structure of the polymer, the drug loading can be effectively controlled. At the same time, it has the characteristics of controlled release in the tumor microenvironment and has significant in vivo and in vitro biological effects.

[0031] Polysarcosine is a polyamino acid material with excellent water solubility and biocompatibility. It can effectively stabilize nanomedicines in vitro and in vivo, resist non-specific protein adsorption, and achieve high drug concentration at lesions. Compared with common water-soluble polyethylene glycol, polysarcosine is much easier to synthesize, and can be synthesized in large quantities at room temperature. Furthermore, it does not accelerate blood clearance. This invention constructs a polysarcosine-modified camptothecin nanomedicine, which can enhance the biological effects of the drug.

[0032] The Psar-b-PCPTG NPs prepared in Example 7 were placed in a dialysis bag (MWCO = 3.5 kDa), and samples were taken at 1 h, 2 h, 4 h, 8 h, 12 h, and 24 h in and without glutathione. The absorbance of the solution was measured, and the corresponding CPT solubility was calculated, thus plotting the drug release characteristic curves of Psar-b-PCPTG NPs under different conditions. Figure 3 It can be seen that CPT remains largely unreleased and does not leak in the absence of glutathione, while it is rapidly released under 10mM glutathione conditions, indicating that Psar-b-PCPTG NPs can effectively control drug release.

[0033] Example 10 shows that after co-culturing PEG-b-PCPTG NPs (Example 8) and PSA-b-PCPTG NPs (Example 7) with 4T1 cells for a period of time, confocal laser scanning microscopy was performed. Figure 4 It can be seen that as the culture time increases, more and more PSar-b-PCPTG NPs will enter 4T1 cells. At the same time, compared with PEG-b-PCPTG NPs, polysarcosine-modified PSar-b-PCPTG NPs can be taken up by 4T1 cells better, and the fluorescence intensity of intracellular CPT is greater.

[0034] As shown in Example 11, approximately 10 spores were seeded in each well of the 96-well plate. 3 Four T1 cells were cultured at 37°C and 5% CO2 for 24 h. Then, the culture medium was removed, and a new culture medium solution containing different concentrations of CPT, polyethylene glycol-modified nanomedicine (PEG-b-PCPTG NPs) (Example 8), and Psar-b-PCPTG NPs (Example 7) was added, and co-cultured for 24 h. After co-culture, the absorbance of the solution at 490 nm was measured using the MTT assay with a microplate reader. The survival rate of cells at different concentrations was calculated, and survival curves of different groups of 4T1 cells were plotted to evaluate the in vitro antitumor activity of Psar-b-PCPTG NPs. Figure 5 It can be seen that PSar-b-PCPTG NPs can kill 4T1 cells more effectively than PEG-b-PCPTG NPs.

[0035] Example 12 shows that a 4T1 subcutaneous mouse tumor model was established when the mouse tumor volume was approximately 65 mm. 3 Near-infrared fluorescent Cy5.5-labeled PEG-b-PCPTG NPs (Example 8) and PSA-b-PCPTG NPs (Example 7) were injected into mice via the tail vein, and near-infrared in vivo imaging was performed on the mice at specified time points. Figure 6 It can be seen that, compared with PEG-b-PCPTG NPs, PSar-b-PCPTG NPs can accumulate and remain in 4T1 mouse tumors better. In particular, the fluorescence intensity in the tumors of mice in the PSar-b-PCPTG NPs group was higher 24 hours after intravenous injection. Attached Figure Description

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] Figure 1 It is polysarcosine-β-polycamptothecin glutamate (PSar-β-PCPTG) in 1 H NMR spectrum.

[0038] Figure 2 This is a representative TEM image of polycamptothecin nanomedicine (PSar-b-PCPTG NPs).

[0039] Figure 3 This is a drug release curve of polycamptothecin nanomedicine (PSar-b-PCPTG NPs).

[0040] Figure 4 This is a 4T1 cell uptake diagram of polycamptothecin nanomedicine (PSar-b-PCPTG NPs).

[0041] Figure 5 This is a 4T1 cytotoxicity graph of psar-b-PCPTG nanomedicine (PSar-b-PCPTG NPs).

[0042] Figure 6 This is a near-infrared image of camptothecin nanomedicine (PSar-b-PCPTG NPs). Detailed Implementation

[0043] The present invention will be further illustrated below with reference to the embodiments, but these embodiments do not limit the scope of protection of the present invention.

[0044] Example 1: Synthesis of disulfide-modified camptothecin (CPT-SS-OH)

[0045] Weigh 348 mg of camptothecin into a Schlenk flask, add 780 mg of 4-dimethylaminopyridine, purge with argon three times, and add 80 mL of freshly distilled dichloromethane. Then, add 20 mL of anhydrous dichloromethane solution containing 200 mg of triphosgene, stir at room temperature in the dark for 3 h, and then add 10 mL of tetrahydrofuran solution containing 771 mg of 2-hydroxyethyl disulfide, stir overnight at room temperature in the dark. Then, dilute with an appropriate amount of anhydrous dichloromethane, wash three times with hydrochloric acid (pH 1.0), twice with saturated sodium chloride aqueous solution, and once with deionized water, and dry with anhydrous sodium sulfate. Filter, rotary evaporate, and purify by column chromatography, with the eluent being dichloromethane:methanol = 50:1. Remove the organic solvent by rotary evaporation to obtain a pale yellow solid with a yield of approximately 70%.

[0046] 1 H NMR (DMSO-d6, 400MHz) δ (ppm): 8.66 (d, 1H), 8.11 (ddd, 2H), 7.83

[0047] (ddd,1H),7.68(ddd,1H),7.05(s,1H),5.49(d,2H),5.26(t,2H),4.81(t,1H),

[0048] 4.29(t,2H),3.59-3.47(m,2H),3.03-2.91(m,2H),2.72(t,2H),2.13(dq,2H),

[0049] 0.88(t,3H).

[0050] Its structure is as follows:

[0051]

[0052] Example 2: Synthesis of Boc-Glutamic Acid Camptothecin Ester (Boc-Glu-SS-CPT)

[0053] 792 mg of CPT-SS-OH was dispersed in 150 mL of anhydrous dichloromethane. Then, 463.5 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 675 mg of Boc-L-glutamic acid-1-tert-butyl ester, and 184 mg of 4-dimethylaminopyridine were added sequentially. The mixture was initially stirred in an ice-water bath, then stirred overnight at room temperature in the dark. The organic phase was washed three times with saturated ammonium bicarbonate solution, saturated sodium chloride solution, and deionized water, dried over a magnesium sulfate-free environment, and purified by column chromatography using a mobile phase of dichloromethane to dichloromethane:methanol = 50:1. The organic solvent was removed by rotary evaporation to give a pale yellow solid in approximately 77% yield.

[0054] 1 H NMR(DMSO-d6,400MHz)δ(ppm): 8.66(d,1H),8.11(ddd,2H),7.83(ddd,1H),7.68(ddd,1H),7.15-7.02(m,1H),5.49(d,2H),5.27(s,2H),4 .29(td,2H),4.15(td,2H),3.82-3.66(m,1H),3.01-2.81(m,4H),2.35-2.07(m,4H),1.91-1.63(m,2H),1.39-1.28(m,18H),0.88(t,3H).

[0055] Its structure is as follows:

[0056]

[0057] Example 3: Synthesis of Camptothecin Glutamate (Glu-SS-CPT)

[0058] 813 mg of Boc-Glu-SS-CPT was dissolved in 5 mL of anhydrous dichloromethane, and an equal volume of trifluoroacetic acid was added. The mixture was stirred for 1.5 h in an ice-water bath. The organic solvent was then rotary evaporated, and the solid was dissolved in a small amount of dichloromethane. This process was repeated twice, and the solid was finally precipitated in anhydrous diethyl ether and dried under vacuum. A pale yellow solid was obtained, with a yield of approximately 86%.

[0059] 1H NMR (DMSO-d6, 400MHz) δ (ppm): 8.66 (s, 1H), 8.20-8.02 (m, 2H), 7.83 (ddd, 1H), 7.68 (ddd, 1H), 7.05 (s, 1H), 5.49 (d, 2H), 5.2 7(s,2H),4.33-4.12(m,4H),3.61(t,1H),3.00-2.87(m,4H),2.44-2.34(m,2H),2.13(dq,2H),1.91(dddd,2H),0.88(t,3H).

[0060] Its structure is as follows:

[0061]

[0062] Example 4: Synthesis of Camptothecin-N-carboxylic anhydride (CPT-NCA)

[0063] 300 mg of Glu-SS-CPT was suspended in 45 mL of freshly distilled tetrahydrofuran, and then 162 mg of triphosgene was added. The mixture was heated to 56 °C until the solution became clear. The solution was concentrated under vacuum, and then 20 mL of tetrahydrofuran was added. Precipitation was then carried out in 40 mL of anhydrous n-hexane. The precipitate was prepared using a tetrahydrofuran:n-hexane ratio of 1:1.

[0064] Wash three times (v / v), dry in a vacuum drying oven, yield approximately 50%.

[0065] 1 H NMR (DMSO-d6, 400MHz) δ (ppm): 9.06 (s, 1H), 8.66 (s, 1H), 8.10 (dd,

[0066] 2H),7.83(ddd,1H),7.68(t,1H),7.05(s,1H),5.55-5.44(m,2H),5.26(s,2H),

[0067] 4.39(dd,1H),4.34-4.23(m,2H),4.15(hept,2H),3.00-2.85(m,4H),2.36(t,2H),

[0068] 2.14(qt,2H),2.05-1.74(m,2H),0.88(t,3H).

[0069] Its structure is as follows:

[0070]

[0071] Example 5: Synthesis of polyglutamic acid camptothecin ester (PCPTG)

[0072] The 25 mL Schlenk flask was purged with argon three times, then 412 mg of CPT-NCA was added. The mixture was then purged with argon three more times, followed by the addition of 5 mL of freshly distilled dichloromethane and 3.0 mg of hexylamine. The reaction was carried out under argon protection for 12 hours, resulting in anhydrous diethyl ether precipitation, which was then dried under vacuum. Finally, the obtained polymer was stored in a refrigerator at 2–8 °C.

[0073] 1 H NMR(DMSO-d6,400MHz)δ(ppm): 9.12-9.01(m,19H),8.66(s,21H),8.15-8.03(m,43H),7.83(ddd,21H),7.68(ddd,24H),7.05(s,22H),5.56-5.40(m ,44H),5.27(s,44H),4.48-4.08(m,109H),3.04-2.82(m,88H),2.36(t,3 0H),2.14(qt,39H),2.00-1.74(m,36H),1.21(d,8H),0.93-0.80(m,64H).

[0074] Its structure is as follows:

[0075]

[0076] Example 6: Synthesis of polysarcosine-b-polycamptothecin glutamate (PSar-b-PCPTG)

[0077] 115 mg of sarcosine-N-carboxylic anhydride was placed in a Schlenk flask, purged with argon three times, and 2 mL of anhydrous dichloromethane was added. Then, 1 mL of a 128 mg solution of PCPTG in anhydrous dichloromethane was rapidly injected into the Schlenk flask. The reaction was then carried out under an argon atmosphere for 24 h. After the reaction was complete, the precipitate was collected in anhydrous diethyl ether and dried under vacuum. Figure 1 It can be seen that the characteristic absorption peaks in the NMR spectrum correspond one-to-one with the structure of PSAr-b-PCPTG.

[0078] 1 H NMR (CDCl3, 400MHz) δ (ppm): 8.39 (d, 20H), 8.18 (t, 21H), 7.98-7.74 (m, 42H), 7.71-7.59 (m, 21H),7.30(d,18H),5.77-5.15(m,81H),4.25(d,301H),3.24-1.90(m,512H),0.96(dt,64H).

[0079] Its structure is as follows:

[0080]

[0081] The above reaction formula is as follows:

[0082]

[0083] Example 7: Preparation of Polycamptothecin Nanomedicine (PSar-b-PCPTG NPs)

[0084] 10 mg of PSar-b-PCPTG was dissolved in 1 mL of dimethyl sulfoxide, and then 9 mL of deionized water was slowly added dropwise at a rate of 8 mL / h. After the addition was complete, the solution was dialyzed to remove the organic solvent. The solution was then lyophilized to obtain PSar-b-PCPTG NPs. Figure 2 It can be seen that the prepared PSar-b-PCPTG NPs are uniform spherical with a size of about 200 nm.

[0085] Example 8: Preparation of polyethylene glycol-modified camptothecin nanomedicine (PEG-b-PCPTG NPs)

[0086] Place 136 mg of CPT-NCA in a Schlenk flask, purge three times with argon gas, and add 2 mL of anhydrous dichloromethane. Then add 50 mg of PEG. 113 A 1 mL solution of anhydrous dichloromethane containing -NH₂ was rapidly injected into the Schlenk flask described above. The reaction was then carried out under an argon atmosphere for 24 h. After the reaction was complete, PEG-b-PCPTG was precipitated in anhydrous diethyl ether. Next, the polymer was similarly dissolved in an appropriate amount of dimethyl sulfoxide, and PEG-b-PCPTG NPs were prepared by solvent removal and dialysis.

[0087] Example 9: Drug release from polycamptothecin nanomedicine (PSar-b-PCPTG NPs)

[0088] The Psar-b-PCPTG NPs prepared in Example 7 were placed in a dialysis bag (MWCO = 3.5 kDa), and samples were taken at 1 h, 2 h, 4 h, 8 h, 12 h, and 24 h in and without glutathione. The absorbance of the solution was measured, and the corresponding CPT solubility was calculated, thus plotting the drug release characteristic curves of Psar-b-PCPTG NPs under different conditions. Figure 3 It can be seen that CPT remains largely unreleased and does not leak in the absence of glutathione, while it is rapidly released under 10mM glutathione conditions, indicating that Psar-b-PCPTG NPs can effectively control drug release.

[0089] Example 10: Cellular uptake experiment of polycamptothecin nanomedicine (PSar-b-PCPTG NPs)

[0090] After co-culturing PEG-b-PCPTG NPs (Example 8) and PSA-b-PCPTG NPs (Example 7) with 4T1 cells for a period of time, confocal laser scanning microscopy was performed. Figure 4 It can be seen that as the culture time increases, more and more PSar-b-PCPTG NPs will enter 4T1 cells. At the same time, compared with PEG-b-PCPTG NPs, polysarcosine-modified PSar-b-PCPTG NPs can be taken up by 4T1 cells better, and the fluorescence intensity of intracellular CPT is greater.

[0091] Example 11: Cytotoxicity assay of polycamptothecin nanomedicine (PSar-b-PCPTG NPs)

[0092] First, seed approximately 10 μL of the solution into each well of the 96-well plate. 3 Four T1 cells were cultured at 37°C and 5% CO2 for 24 h. Then, the culture medium was removed, and a culture medium solution containing different concentrations of CPT, polyethylene glycol-modified nanomedicine (PEG-b-PCPTGNPs) (Example 8), and Psar-b-PCPTGNPs (Example 7) was added, and co-cultured for 24 h. After co-culture, the absorbance of the solution at 490 nm was measured using the MTT assay with a microplate reader. The survival rate of cells at different concentrations was calculated, and survival curves of different groups of 4T1 cells were plotted to evaluate the in vitro antitumor activity of Psar-b-PCPTGNPs. Figure 5 It can be seen that PSar-b-PCPTG NPs can kill 4T1 cells more effectively than PEG-b-PCPTG NPs.

[0093] Example 12: Animal experiments with polycamptothecin nanomedicine (PSar-b-PCPTG NPs)

[0094] First, a 4T1 subcutaneous mouse tumor model was established until the mouse tumor volume reached approximately 65 mm. 3 Near-infrared fluorescent Cy5.5-labeled PEG-b-PCPTG NPs (Example 8) and PSA-b-PCPTG NPs (Example 7) were injected into mice via the tail vein, and near-infrared in vivo imaging was performed on the mice at specified time points. Figure 6It can be seen that, compared with PEG-b-PCPTG NPs, PSar-b-PCPTG NPs can accumulate and remain in 4T1 mouse tumors better. In particular, the fluorescence intensity in the tumors of mice in the PSar-b-PCPTG NPs group was higher 24 hours after intravenous injection.

[0095] The present invention is not limited to the specific technical solutions described in the above embodiments. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by the present invention.

Claims

1. A polycamptothecin nanomedicine, characterized in that: The aforementioned camptothecin nanomedicine is composed of the amphiphilic block polymer polysarcosine- b - Polyglutamic acid camptothecin ester (PSar- b -PCPTG) self-assembled nanomedicines, the PSar- b -PCPTG has the following structure: ； The described polycamptothecin nanomedicine can achieve efficient loading of camptothecin; the polycamptothecin nanomedicine has good stability and can effectively avoid camptothecin leakage, while under the reducing conditions of glutathione, it can achieve precise and rapid release of camptothecin, which can be used to effectively inhibit the growth of tumor cells.

2. The polycamptothecin nanomedicine according to claim 1, characterized in that: The aforementioned camptothecin nanomedicine is a uniform spherical shape with a size of 200 nm and a camptothecin loading of 34.4%.

3. The method for preparing polycamptothecin nanomedicine according to claim 1, characterized in that: Includes the following steps: Step 1: Synthesis of disulfide-modified camptothecin (CPT-SS-OH) Weigh 348 mg of camptothecin into a Schlenk flask, add 780 mg of 4-dimethylaminopyridine, purge with argon three times, and add 80 mL of freshly distilled dichloromethane. Then, add 20 mL of anhydrous dichloromethane solution containing 200 mg of triphosgene, stir at room temperature in the dark for 3 h, add 10 mL of tetrahydrofuran solution containing 771 mg of 2-hydroxyethyl disulfide, and stir overnight at room temperature in the dark. Then, dilute with an appropriate amount of anhydrous dichloromethane, wash three times with hydrochloric acid at pH 1.0, wash twice with saturated sodium chloride aqueous solution, wash once with deionized water, and dry with anhydrous sodium sulfate. Filter, rotary evaporate, and purify by column chromatography with dichloromethane:methanol = 50:1 as the eluent. Remove the organic solvent by rotary evaporation to obtain a pale yellow solid with a yield of 70%. Step 2: Synthesis of Boc-Glutamic Acid Camptothecin Ester (Boc-Glu-SS-CPT) 792 mg of CPT-SS-OH was dispersed in 150 mL of anhydrous dichloromethane. 463.5 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 675 mg of Boc-L-glutamic acid-1-tert-butyl ester, and 184 mg of 4-dimethylaminopyridine were added sequentially. The mixture was initially stirred in an ice-water bath, then stirred overnight at room temperature in the dark. The organic phase was washed three times with saturated ammonium bicarbonate solution, saturated sodium chloride solution, and deionized water, dried without magnesium sulfate, and purified by column chromatography using dichloromethane to dichloromethane:methanol = 50:1 as the mobile phase. The organic solvent was removed by rotary evaporation to obtain a pale yellow solid in 77% yield. Step 3: Synthesis of Camptothecin Glutamate (Glu-SS-CPT) 813 mg of Boc-Glu-SS-CPT was dissolved in 5 mL of anhydrous dichloromethane, and an equal volume of trifluoroacetic acid was added. The mixture was stirred for 1.5 h in an ice-water bath. The organic solvent was then rotary evaporated, and the solid was dissolved in a small amount of dichloromethane. The reaction was repeated twice by rotary evaporation. Finally, the solid was precipitated in anhydrous diethyl ether and dried under vacuum to obtain a pale yellow solid with a yield of 86%. Step 4, Camptothecin glutamate - N Synthesis of α-carboxylic anhydride (CPT-NCA) 300 mg of Glu-SS-CPT was suspended in 45 mL of freshly distilled tetrahydrofuran, and then 162 mg of triphosgene was added. The mixture was heated to 56 °C until the solution became clear. The solution was concentrated under vacuum, and then 20 mL of tetrahydrofuran was added. The solution was precipitated in 40 mL of anhydrous n-hexane. The precipitate was washed three times with tetrahydrofuran:n-hexane = 1:2 (v / v) and dried in a vacuum drying oven. The yield was 50%. Step 5: Synthesis of polyglutamic acid camptothecin ester (PCPTG) The 25 mL Schlenk flask was purged with argon three times, 412 mg of CPT-NCA was added, and the flask was purged with argon three more times. Then, 5 mL of freshly distilled dichloromethane and 3.0 mg of hexylamine were added. The mixture was reacted under argon protection for 12 h, and anhydrous diethyl ether precipitate was obtained. The precipitate was then dried under vacuum. Finally, the obtained polymer was stored in a refrigerator at 2-8°C. Step 6, Polysarcosine- b -Polycamptothecin glutamate (PSar- b Synthesis of -PCPTG 115 mg of creatine- N The carboxylic anhydride was placed in a Schlenk flask, purged with argon three times, and 2 mL of anhydrous dichloromethane was added. Then, 1 mL of anhydrous dichloromethane solution containing 128 mg of PCPTG was rapidly injected into the Schlenk flask. The reaction was then carried out under an argon atmosphere for 24 h. After the reaction was completed, the precipitate was placed in anhydrous diethyl ether and dried under vacuum. Step 7, Polycamptothecin Nanomedicine (PSar- b Preparation of -PCPTG NPs 10 mg of PSA b PCPTG was dissolved in 1 mL of dimethyl sulfoxide, and then 9 mL of deionized water was slowly added dropwise at a rate of 8 mL / h. After the addition was complete, the solution was dialyzed to remove the organic solvent. The solution was then lyophilized to obtain PSA- b -PCPTG NPs.

4. The method for preparing polycamptothecin nanomedicine according to claim 3, characterized in that: The reaction route is as follows: 。

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