A functional drug-loaded small molecule peptide targeting HER2-positive breast cancer

Abstract

The present invention discloses a functional drug-carrying small molecule peptide targeting HER2-positive breast cancer, and belongs to the technical field of the establishment and preparation of small molecule peptide nano drug carrier system. The peptide contains HER2 targeting peptide, responds to alkaline phosphatase in the tumor microenvironment, and can be used as a drug carrier, and the structural formula is shown in Figure 1. The functional drug-carrying small molecule peptide of the present invention can increase the cytotoxicity to tumor cells and reduce the toxic side effects to normal cells. DC / Pep1 undergoes morphological changes under the induction of ALP in the tumor microenvironment, and it co-loads DOX and CUR, which increases the retention time of the combined drug in HER2-positive tumor cells, more effectively inhibits tumor cell migration and promotes cell apoptosis.

Description

Technical Field

[0001] The present invention belongs to the technical field of establishment and preparation of small molecule peptide nano drug carrier system, and specifically relates to a functional drug-carrying small molecule peptide targeting HER2 positive breast cancer. Background Art

[0002] In approximately 15-20% of breast cancers, human epidermal growth factor receptor 2 (HER2) is overexpressed. HER2-positive breast cancer is a relatively serious type in the entire breast cancer family, with characteristics such as high malignancy, rapid disease progression, prone to lymph node metastasis, and poor prognosis. The invasiveness and metastasis of cancer, the inhibition of tumor cell apoptosis, and the reduction in overall survival rate are all related to the expression of HER2. Various chemotherapy drugs that inhibit tumor cell growth or directly kill tumor cells have been widely studied, but the shortcomings of these chemotherapy drugs have gradually emerged: 1) lack of specificity, non-targeted cytotoxicity, and strong toxic side effects; 2) chemotherapy drugs are easily pumped out by tumor cells, insufficient drug accumulation, resulting in multidrug resistance at the tumor site, etc.

[0003] In order to enhance the targeting of chemotherapy drugs, a large number of researchers have conducted research on drug delivery systems. The development of nano drug delivery systems has greatly improved the effectiveness and safety of cancer chemotherapy. Studies have reported that nanocarriers can release drugs through pathological signal stimulation and target damaged sites. In early studies, researchers found that nanoparticles can accumulate in tumor tissues by enhancing permeability and retention (EPR effect), effectively inhibiting the development of tumors. However, different types of tumor tissues have different vascular structures and blood flow characteristics, which limits the application of the EPR effect. The use of HER2-targeted peptide nanocarriers provides ideas for targeting breast cancer cells that overexpress HER2.

[0004] In response to insufficient drug accumulation, there are currently a large number of studies on drug efflux proteins. Some studies have reported that melatonin can synergize with epirubicin to increase the accumulation of epirubicin in tumor cells by inhibiting the expression and function of P-gp drug efflux proteins. Other studies have shown that by enhancing C1orf115 gene expression, the drug efflux pump ABCB1 / MDR1 is dysregulated, thereby enhancing drug sensitivity. However, in addition to inhibiting drug efflux proteins, there are few reports on the changes of drug delivery systems in the tumor microenvironment. In the tumor microenvironment, ALP expression is upregulated, which provides a new idea for tumor treatment and a new strategy for the development of nanocarriers. Summary of the invention

[0005] In order to overcome the above defects, the present invention provides a functional drug-loaded small molecule peptide targeting HER2-positive breast cancer. The peptide encapsulates any one of doxorubicin (DOX) and curcumin (CUR) or a combination thereof, and can self-assemble into spherical nanoparticles (DC / Pep1), which are then converted into nanofibers under the environment of alkaline phosphatase (ALP), resulting in a longer retention time of the drug in tumor cells and a higher drug concentration. Ultimately, DC / Pep1 inhibits tumor growth and migration and enhances tumor cell apoptosis.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A functional drug-carrying small molecule peptide targeting HER2-positive breast cancer, the peptide contains a HER2-targeting peptide, responds to alkaline phosphatase in the tumor microenvironment, and can be used as a drug carrier, and the structural formula is:

[0008] .

[0009] The present invention also provides the use of a functional drug-carrying small molecule peptide targeting HER2-positive breast cancer as a drug carrier, wherein the functional drug-carrying small molecule peptide is a functional drug-carrying small molecule peptide that can be prepared as a drug carrier, and the functional drug-carrying small molecule peptide encapsulates chemotherapy drugs and self-assembles into spherical nanoparticles.

[0010] Preferably, the chemotherapy drug includes any one of doxorubicin and curcumin or a combination thereof.

[0011] The present invention also provides a functional drug-carrying small molecule peptide drug carrier targeting HER2 positive breast cancer, wherein the functional drug-carrying small molecule peptide drug carrier comprises the functional drug-carrying small molecule peptide forming spherical nanoparticles that can be used as a drug carrier.

[0012] Preferably, the functional drug-carrying small molecule peptide drug-carrying carrier responds to alkaline phosphatase in the tumor microenvironment, and the self-assembly morphology is transformed into nanofiber drug release, and the drug retention time in tumor cells is prolonged and the drug concentration is higher.

[0013] The present invention also provides a method for preparing a functional drug-carrying small molecule peptide targeting HER2-positive breast cancer, which encapsulates chemotherapy drugs and self-assembles into spherical nanoparticles, comprising the following steps: dissolving the functional drug-carrying small molecule peptide in HEPES buffer to obtain a functional drug-carrying small molecule peptide solution of a required concentration, incubating the functional drug-carrying small molecule peptide solution at room temperature, mixing the chemotherapy drugs in dimethyl sulfoxide, then adding the functional drug-carrying small molecule peptide solution and HEPES buffer, and ultrasonicating to obtain drug-carrying functional drug-carrying small molecule peptide spherical nanoparticles.

[0014] Preferably, the pH value of the HEPES buffer is 7.4.

[0015] Preferably, the method comprises the following steps: dissolving 0.5 mg of the functional drug-carrying small molecule peptide in 1 mL of HEPES buffer, incubating the functional drug-carrying small molecule peptide solution at room temperature, mixing 0.1 mg of chemotherapy drugs in 20 μL of dimethyl sulfoxide, then adding 0.5 mg of the functional drug-carrying small molecule peptide solution and 980 μL of HEPES buffer, ultrasonicating for 5 minutes to obtain drug-loaded functional drug-carrying small molecule peptide spherical nanoparticles, and incubating at room temperature.

[0016] Beneficial effects of the present invention:

[0017] The functional drug-carrying small molecule peptide drug-carrying system DC / Pep1 of the present invention can target HER2-positive breast cancer cells, and can increase the cytotoxicity to tumor cells and reduce the toxic side effects to normal cells. DC / Pep1 undergoes a morphological transformation under the induction of ALP in the tumor microenvironment, and it co-loads DOX and CUR, which increases the retention time of the combined drug in HER2-positive tumor cells. Compared with DC / Pep2, which cannot be transformed in morphology, DC / Pep1 is more effective in inhibiting tumor cell migration and promoting cell apoptosis. As a drug carrier, the functional drug-carrying polypeptide that responds to the ALP enzyme can be used as a promising tool in tumor treatment, which provides a theoretical and experimental basis for the development of a new drug delivery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the structural formula of the functional drug-carrying small molecule peptide Pep1 of the present invention;

[0019] Figure 2 is the structural formula of the control peptide Pep2 of the present invention;

[0020] Figure 3 The mass spectrum of the functional drug-carrying small molecule peptide Pep1 of the present invention, wherein M is the sample molecule and H+ is the hydrogen ion;

[0021] Figure 4 The mass spectrum of the functional drug-carrying small molecule peptide Pep2 of the present invention, wherein M is the sample molecule and H+ is the hydrogen ion;

[0022] Figure 5 This is a high performance liquid chromatogram of the functional drug-carrying small molecule peptide Pep1 of the present invention;

[0023] Figure 6 is a high performance liquid chromatogram of the control peptide Pep2 of the present invention;

[0024] Figure 7Characterization of functional drug-loaded small molecule peptides and ALP response, wherein A is a transmission electron microscopy image of Pep1, B is a transmission electron microscopy image of DC / Pep1, C is a transmission electron microscopy image of DC / Pep1 after co-incubation with ALP for 120 hours, D is a transmission electron microscopy image of Pep2, E is a transmission electron microscopy image of DC / Pep2, and F is a transmission electron microscopy image of DC / Pep2 after co-incubation with ALP for 120 hours;

[0025] Figure 8 The potential characterization diagram of the functional drug-carrying small molecule peptide, where A is the Zeta potential of Pep1 and DC / Pep1, and B is the Zeta potential of Pep2 and DC / Pep2;

[0026] Fig. 9 The figure is the cytotoxicity evaluation and drug release detection of functional drug-loaded small molecule peptides, where A is the survival rate of SKBR3 cells after co-incubation with Pep1 and Pep2, B is the survival rate of human umbilical vein endothelial cells (HUVEC) after co-incubation with Pep1 and Pep2, C is the cumulative release rate curve of DOX; D is the cumulative release rate curve of CUR;

[0027] Fig.10 The chromatographic peaks of the functional drug-carrying small molecule peptide before and after the addition of ALP were detected by HPLC, where A is the HPLC spectrum of Pep1 without the addition of ALP, B is the HPLC spectrum of Pep1 after the addition of ALP for 0.5 h, and C is the peak area ratio of Pep1;

[0028] Fig.11 The cellular uptake of dual drugs (DOX and CUR) co-loaded with functional drug-loaded small molecule peptides in SKBR3 breast cancer cells was detected by flow cytometry, where A is the fluorescence intensity quantification of DOX uptake by DC, DC / Pep2 and DC / Pep1 after co-incubation with SKBR3 for 0.25 h, B is the fluorescence intensity quantification of CUR uptake by DC, DC / Pep2 and DC / Pep1 after co-incubation with SKBR3 for 0.25 h, C is the fluorescence intensity quantification of DOX uptake by DC, DC / Pep2 and DC / Pep1 after co-incubation with SKBR3 for 1 h, and D is the fluorescence intensity quantification of CUR uptake by DC, DC / Pep2 and DC / Pep1 after co-incubation with SKBR3 for 1 h. *P<0.05, **P<0.01, ***P<0.001.

[0029] Fig.12Figure 1 shows the experimental diagram of Pep1 prolonging the retention of drugs in SKBR3 cells, where A is the laser confocal scanning microscopy image of DOX and CUR fluorescence retention in SKBR3 cells after they took up DC, DC / Pep2 and DC / Pep1 for 48 hours, scale bar: 100 μm, B is the quantification of the average fluorescence intensity of DOX retention for 48 hours, C is the quantification of the average fluorescence intensity of CUR retention for 48 hours, *P<0.05, **P<0.01, ***P<0.001;

[0030] Fig.13 The effect of Pep1 co-loaded drugs on SKBR3 cell migration, where A is a picture of SKBR3 cell migration after peptide drug treatment, scale bar: 500 μm, B is a quantification of SKBR3 cell migration rate at 24 h, C is a quantification of SKBR3 cell migration rate at 48 h, *P<0.05, **P<0.01;

[0031] Fig.14 Effects of DC / Pep1 on apoptosis of SKBR3 cells, *P<0.05, **P<0.01, ***P<0.001. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below with reference to specific embodiments, but this does not limit the protection scope of the present invention.

[0033] Example 1

[0034] A functional drug-carrying small molecule peptide targeting HER2-positive breast cancer, the peptide contains a HER2-targeting peptide, responds to alkaline phosphatase in the tumor microenvironment, and can be used as a drug carrier. The structural formula is shown in Figure 1 , abbreviated as Pep1. As a control peptide, a functional drug-carrying small molecule peptide Pep2 without HER2 targeting peptide was designed, and the structural formula is shown in Figure 2 The relative molecular weights of Pep1 and Pep2 were analyzed by electrospray ionization mass spectrometry (ESI-MS). The results for Pep1 are shown in Figure 3 , the results of Pep2 are shown in Figure 4 The purity of Pep1 solution and Pep2 solution was analyzed by ThermoFisher Ultra3000 system (Thermo Fisher Scientific, USA). The results of Pep1 are shown in Figure 5 , the results of Pep2 are shown in Figure 6 .

[0035] Conclusion: The functional drug-carrying small molecule peptides Pep1 and Pep2 were successfully synthesized with a purity greater than 95%.

[0036] Example 2

[0037] Functional drug-loaded small molecule peptide spherical nanoparticles and preparation method of functional drug-loaded small molecule peptide spherical nanoparticles

[0038] 0.5 mg of the functional drug-carrying small molecule peptide Pep1 obtained in Example 1 was dissolved in 1 mL of HEPES buffer to obtain a functional drug-carrying small molecule peptide Pep1 solution, which was incubated at room temperature. Similarly, a Pep2 solution was prepared and incubated at room temperature. 0.1 mg of the chemotherapy drug doxorubicin (DOX) was mixed in 20 μL of dimethyl sulfoxide, and then 0.5 mg of the functional drug-carrying small molecule peptide solution and 980 μL of HEPES buffer were added respectively, and ultrasonicated for 5 minutes to obtain drug-carrying functional drug-carrying small molecule peptide spherical nanoparticles (D / Pep1), which were incubated at room temperature. Similarly, drug-carrying functional drug-carrying small molecule peptide spherical nanoparticles (D / Pep2) were prepared and incubated at room temperature. DOX (0.1 mg) and curcumin (CUR) (0.025 mg) were mixed together in dimethyl sulfoxide (20 μL), and then 0.5 mg of functional drug-carrying small molecule peptide Pep1 solution and 980 μL of HEPES buffer were added, and ultrasonic treatment was performed for 5 minutes to obtain drug-carrying functional drug-carrying small molecule peptide spherical nanoparticles DC / Pep1, which were incubated at room temperature; similarly, drug-carrying functional drug-carrying small molecule peptide spherical nanoparticles (DC / Pep2) were prepared and incubated at room temperature. The chemotherapeutic drugs used in this embodiment are DOX and CUR, and other chemotherapeutic drugs can also be selected in practical applications.

[0039] Example 3

[0040] Transmission electron microscopy

[0041] Transmission electron microscopy was used to observe the self-assembly behavior of functional drug-carrying small molecule peptides. A 300-mesh copper mesh was covered on the 30-mesh peptide solution, adsorbed for 6 minutes, and then stained with uranyl acetate. After the sample was dried, it was observed using a transmission electron microscope (TEM). The results are shown in Figure 7 .

[0042] Conclusion: Pep1 is a uniform spherical shape under transmission electron microscopy ( Figure 7 A), after encapsulating DOX and CUR (DC / Pep1) is still in a spherical state ( Figure 7 B), and after adding ALP, it becomes a fibrous structure ( Figure 7 C); Pep2 is also spherical in shape ( Figure 7 D), drug encapsulation (DC / Pep2) ( Figure 7 E) and after adding ALP enzyme ( Figure 7 F), the morphology did not change significantly.

[0043] Example 4

[0044] Particle size potential analysis

[0045] The Zetasizer Nano ZS90 device was used to measure the Zeta potential of the peptide solution, the drug-loaded peptide solution, and the drug-loaded peptide solution after enzyme response. Figure 8 .

[0046] in conclusion:

[0047] The potentials of Pep1 and Pep2 are negative. After encapsulating DOX and CUR, the zeta potential of the drug-loaded experimental peptide and the drug-loaded control peptide increased.

[0048] Example 5

[0049] CCK8 cytotoxicity assay

[0050] The CCK8 kit was used to detect the cytotoxicity of the peptide solution on HUVEC cells and SKBR3 cells. HUVEC cells and SKBR3 cells were inoculated into 96-well plates, and the peptide solution was added to react for 12 hours. Then, the CCK8 reagent was added and incubated at 37°C for 4 hours. The OD value at 450 nm was detected every hour. The results are shown in Fig. 9 A. Fig. 9 B.

[0051] in conclusion:

[0052] After 12 hours of co-culture with Pep1, the survival rate of HUVEC was about 96.2%, and the survival rate of SKBR3 was about 75.0%; after 12 hours of co-culture with Pep2, the survival rate of HUVEC was about 99.7%, and the survival rate of SKBR3 was about 92.9%. After the amphiphilic peptides were co-cultured with HUVEC cells and SKBR3 cells for 24 hours, it was interesting that Pep1 inhibited the growth of SKBR3 cells more effectively than Pep2. Pep1 and Pep2 had little effect on the survival rate of HUVECs.

[0053] Example 6

[0054] In vitro drug release

[0055] In order to evaluate the drug release ability of Pep1 co-loaded with DOX and CUR in vitro, Pep1 without alkaline phosphatase was used as the control group to investigate the drug release behavior of Pep1 under enzyme catalysis. The peptide, DOX, and CUR were dissolved in HEPES buffer at a mass ratio of 20:4:1, ultrasonically treated for 5 minutes, and incubated at room temperature for 12 hours. The prepared peptide solution was transferred to a dialysis bag and dialyzed with 2L pure water for 1 hour. 1U ALP was added to each milliliter of peptide solution in the experimental group, and no ALP was added to the control group. The dialysis bag was immersed in 25mL PBS and placed in a 37℃ shaker for drug release. 2mL of release sample was extracted at a specific time, and 2mL of new release medium was added. The absorbance of the solution at 488 nm (DOX) and 425 nm (IND) was detected using a UV-visible spectrophotometer (Thermo, Evolution 300, USA). The results are shown in Fig. 9 C. Fig. 9 D.

[0056] Conclusion: After 72 hours of drug release, the release rate of DOX without the addition of alkaline phosphatase was about 60.0%, and the release rate of DOX after the addition of ALP enzyme was about 83.0% ( Fig. 9 C); the release rate of CUR after adding ALP enzyme was about 82.6%, while the release rate of CUR without adding ALP enzyme was about 55.1% ( Fig. 9 D). Pep1 has good ALP enzyme response ability and can undergo morphological changes under the induction of ALP enzyme, which affects and controls the release of drugs.

[0057] Example 7

[0058] ALP responsiveness assay

[0059] The chromatographic peaks of Pep1 before and after the addition of ALP were detected by HPLC. The results are shown in Fig.10 .

[0060] Conclusion: When ALP enzyme was not added, Pep1 showed a substrate peak at about 9.2 min ( Fig.10 A), 0.5 h after adding ALP, a new product peak appeared around 10.0 min ( Fig.10 B), which shows that Pep1 is responsive to ALP and new products are generated under the induction catalysis of ALP. At this time, the substrate peak area is 60.6% of the initial ( Fig.10 C). Pep1 is responsive to ALP and produces new products. This change in primary structure further leads to a change in the self-assembly morphology.

[0061] Example 8

[0062] Cellular uptake experiments

[0063] Free DOX and CUR were abbreviated as DC, Pep2 co-loaded with DOX and CUR (DC / Pep2), and Pep1 co-loaded with DOX and CUR (DC / Pep1) were co-incubated with SKBR3 cells, and the uptake of DC, DC / Pep2, and DC / Pep1 by SKBR3 cells was analyzed by flow cytometry. The fluorescence of DOX and CUR at different incubation times was quantitatively analyzed.

[0064] The operation steps are as follows: cells were seeded into the well plate, and the preparations (DC, DC / Pep2, DC / Pep1) were added after they adhered to the wall. After the cells were added with the preparations and incubated for 0.25h and 1h, they were digested with EDTA-free trypsin. The cells were washed 3 times with PBS and the cell uptake was detected by flow cytometry. The results are shown in Fig.11 .

[0065] Conclusion: The DC / Pep1 group had a higher fluorescence intensity, followed by the DC / Pep2 group, and the fluorescence intensity of free DC was the weakest. At 0.25 h of the experiment, the intensity of DOX uptake by the DC / Pep1 group was about 1.4 times and 2.9 times that of the DC / Pep2 group and the free DC group, respectively ( Fig.11 A); The intensity of CUR uptake in the DC / Pep1 group was approximately 1.3 times and 2.5 times that of the DC / Pep2 group and the free DC group, respectively ( Fig.11 B). When the intake time was extended to 1 hour, the intensity of DOX uptake in the DC / Pep1 group was approximately 1.3 times and 2.1 times that of the DC / Pep2 group and the free DC group, respectively ( Fig.11 C); the intensity of CUR uptake in the DC / Pep1 group was approximately 1.3 times and 2.9 times that of the DC / Pep2 group and the free DC group, respectively ( Fig.11 D). The results showed that DC / Pep1 loaded with DOX and CUR could bind to HER2-positive breast cancer cells more effectively than Pep2 and be internalized by the cells.

[0066] Example 9

[0067] Experiments to enhance drug accumulation in breast cancer cells

[0068] The retention of peptides in SKBR3 cells was detected by laser confocal scanning microscopy. SKBR3 cells were seeded into well plates, and preparations (DC, DC / Pep2, DC / Pep1) were added after adherence. After the preparations were co-cultured with the adherent cells for 1 hour, the cell culture medium was removed, and fresh serum-free medium was added. The culture was continued for 48 hours. After fixation, the cell nuclei were stained with DAPI, and the retention of peptide preparations in the cells was photographed under a laser confocal microscope. The retention images of DOX and CUR in the cells were observed using a laser confocal scanning microscope when SKBR3 cells took in DC, DC / Pep2, and DC / Pep1, respectively, 48 hours later ( Fig.12 A), and the red and green average fluorescence intensities were quantitatively analyzed ( Fig.12 B, 12C).

[0069] Conclusion: The confocal images show that the fluorescence intensity of DOX in free DCs was weak after 48 h. In the DC / Pep2 group, the red fluorescence of DOX was mainly present in the cytoplasm, while in the DC / Pep1 group, the red fluorescence of DOX was not only present in the cytoplasm but also in the nucleus. The average red fluorescence intensity of DC / Pep1 was about 1.7 times and 3.9 times that of the DC / Pep2 group and the DC group, respectively ( Fig.12 B). The DC and DC / Pep2 groups showed weak green fluorescence, while the DC / Pep1 group still had more CUR green fluorescence in the cytoplasm, and the average green fluorescence intensity of DC / Pep1 was about 1.9 times and 3.6 times that of the DC / Pep2 group and DC group, respectively ( Fig.12 C). This indicates that DC / Pep1 can prolong the retention time of drugs in SKBR3 cells, thereby more effectively exerting drug effects in tumor cells.

[0070] Example 9

[0071] Scratch test

[0072] The scratch experiment verified that the drug-loaded peptide has the ability to inhibit tumor cell migration. The experiment was divided into six groups: HEPES, DC, D / Pep2, D / Pep1, DC / Pep2, and DC / Pep1. SKBR3 cells were inoculated into a six-well plate. After reaching the scratch density, the cells were scratched and the corresponding grouping reagents were added to each well. The scratch healing conditions at 0h, 24h, and 48h were photographed under an inverted microscope to verify the ability of Pep1 drug to inhibit SKBR3 cell migration. The scratch experiment was used to study the effect of Pep1 co-loaded with DOX and CUR on the lateral migration ability of SKBR3 cells. The results are shown in Fig.13 .

[0073] Conclusion: At 24 hours, both DC / Pep1 and DC / Pep2 inhibited the motility of SKBR3 cells, but the inhibitory effect of DC / Pep1 was more obvious ( Fig.13 A. Fig.13 B). At 48h, the inhibition of SKBR3 cell migration by DC / Pep1 was more obvious ( Fig.13 A. Fig.13 C). This indicates that Pep1-encapsulated DOX and CUR can more effectively inhibit cell migration compared with free drugs and control peptide-loaded drugs.

[0074] Example 10

[0075] DC / Pep1 promotes apoptosis of breast cancer cells

[0076] We used FITC-Annexin V / PI double staining technique to stain the cells, and then used flow cytometry to determine the cell apoptosis rate. Fig.14 .

[0077] Conclusion: The statistics of cell apoptosis rate showed that the total apoptosis rate (early apoptosis and late apoptosis) induced by SKBR3, DC, D / Pep2, D / Pep1, DC / Pep2 and DC / Pep1 groups were 15.2%, 22.3%, 26.4%, 31.3%, 33.3% and 35.3%, respectively. Compared with DC, D / Pep2, D / Pep1 and DC / Pep2, DC / Pep1 significantly increased the apoptosis rate, prolonged the exposure of tumor cells to chemotherapeutic drugs, promoted apoptosis, and CUR could synergistically enhance the anti-tumor effect of the chemotherapeutic drug DOX and down-regulate angiogenesis-related factors.

Claims

1. A functional drug-carrying small molecule peptide targeting HER2-positive breast cancer, characterized in that: The peptide contains a HER2 targeting peptide, responds to alkaline phosphatase in the tumor microenvironment, and can be used as a drug carrier. The structural formula is: 。 2. A functional drug-carrying small molecule peptide targeting HER2-positive breast cancer is prepared as a drug-carrying carrier, characterized in that: The functional drug-carrying small molecule peptide is the functional drug-carrying small molecule peptide that can be used as a drug carrier as described in claim 1, and the functional drug-carrying small molecule peptide encapsulates the chemotherapeutic drug and self-assembles into spherical nanoparticles.

3. The use of the functional drug-carrying small molecule peptide according to claim 2 as a drug-carrying carrier, characterized in that: The chemotherapy drugs include any one of doxorubicin and curcumin or a combination thereof.

4. A functional small molecule peptide drug carrier targeting HER2-positive breast cancer, characterized in that: The functional drug-carrying small molecule peptide drug carrier comprises the functional drug-carrying small molecule peptide that can be used as a drug carrier as described in claim 1.

5. The functional drug-carrying small molecule peptide drug-carrying carrier according to claim 4, characterized in that: The functional drug-carrying small molecule peptide drug-carrying carrier responds to alkaline phosphatase in the tumor microenvironment, and the self-assembly morphology is transformed into nanofiber drug release, and the drug retention time in tumor cells is prolonged and the drug concentration is higher.

6. A method for preparing a functional drug-carrying small molecule peptide targeting HER2-positive breast cancer, which encapsulates chemotherapy drugs and self-assembles into spherical nanoparticles, characterized in that: The method comprises the following steps: dissolving the functional drug-carrying small molecule peptide described in claim 1 in a HEPES buffer to obtain a functional drug-carrying small molecule peptide solution of a desired concentration, incubating the functional drug-carrying small molecule peptide solution at room temperature, mixing a chemotherapy drug in dimethyl sulfoxide, then adding the functional drug-carrying small molecule peptide solution and the HEPES buffer, and ultrasonicating to obtain drug-carrying functional drug-carrying small molecule peptide spherical nanoparticles.

7. The method for preparing functional drug-carrying small molecule peptides encapsulating chemotherapy drugs and self-assembling into spherical nanoparticles according to claim 6, characterized in that: The pH value of the HEPES buffer is 7.

4.

8. The method for preparing a functional drug-carrying small molecule peptide that encapsulates a chemotherapeutic drug and self-assembles into spherical nanoparticles according to any one of claims 6 or 7, characterized in that: The method comprises the following steps: dissolving 0.5 mg of the functional drug-carrying small molecule peptide according to claim 1 in 1 mL of HEPES buffer, incubating the functional drug-carrying small molecule peptide solution at room temperature, mixing 0.1 mg of chemotherapy drugs in 20 μL of dimethyl sulfoxide, then adding 0.5 mg of the functional drug-carrying small molecule peptide solution and 980 μL of HEPES buffer, ultrasonicating for 5 minutes to obtain drug-carrying functional drug-carrying small molecule peptide spherical nanoparticles, and incubating at room temperature.

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