CN113372412A

CN113372412A - Cell-targeted polypeptide for treating bone tumor and preparation method and application thereof

Info

Publication number: CN113372412A
Application number: CN202110387572.XA
Authority: CN
Inventors: 林开利; 王仡桐; 崔金婕; 王旭东; 张雷
Original assignee: Ninth Peoples Hospital Shanghai Jiaotong University School of Medicine
Current assignee: Ninth Peoples Hospital Shanghai Jiaotong University School of Medicine
Priority date: 2021-04-09
Filing date: 2021-04-09
Publication date: 2021-09-10
Anticipated expiration: 2041-04-09
Also published as: CN113372412B

Abstract

The invention belongs to the field of biological medicine research and development, and particularly relates to a cell targeting polypeptide for treating bone tumor, and a preparation method and application thereof. The polypeptide has a structure shown in a formula I; the formula I is Dm-X-Rn-C, wherein m is the number of aspartic acid, and m is more than or equal to 6 and less than or equal to 10; n is the number of arginine, n is more than or equal to 6 and less than or equal to 10; the X is a polypeptide fragment that can be recognized and cleaved by MMPs. The polypeptide-modified polydopamine nanoparticle taking a metal organic framework as a core is loaded with an anti-tumor drug adriamycin, so that the targeting effect can be obviously enhanced, and the toxic and side effects of the drug can be reduced.

Description

Cell-targeted polypeptide for treating bone tumor and preparation method and application thereof

Technical Field

The invention relates to the technical field of medicines, in particular to a cell targeting polypeptide for treating bone tumor and a preparation method and application thereof.

Background

Malignant bone tumor is a common tumor which is difficult to cure, and is still a great clinical problem. Surgery and chemotherapy are the primary methods of clinical treatment of bone tumors. Surgery can extend the life cycle of bone tumor patients, but surgical margins or small lesions can lead to tumor recurrence. Chemotherapy is a commonly used postoperative adjuvant therapy in the treatment of bone tumors. Chemotherapy drugs used clinically usually adopt a systemic administration method, and lack targeting, so that effective treatment concentration cannot be achieved at bone tumor sites, resulting in poor chemotherapy effect. In addition, chemotherapy has serious side effects and is easy to generate drug resistance. The bone microenvironment provides fertile soil for the recruitment, survival and development of tumor cells. The tumor cells in the bone microenvironment secrete cytokines to stimulate the generation of osteoclasts, the mature osteoclasts absorb bone matrixes to release growth factors, the growth of tumors is promoted, a vicious circle is formed between the proliferation of the tumor cells and the bone absorption, and the bone microenvironment also provides a barrier for the clinical chemotherapy of malignant bone tumors. This is because stromal cell derived factor-1 and interleukin-6 produced by bone marrow stromal cells mediate homing, survival and proliferation of tumor cells, while integrin-mediated adhesion sequesters tumor cells in this protective environment. This "barrier" effect makes it difficult for tumor targeting molecules to further target bone tumor cells. Photothermal therapy has been considered as a very promising approach for tumor therapy, and Polydopamine (PDA) nanoparticles are a class of nanoparticles with high photothermal conversion efficiency and excellent biocompatibility, but their non-specific distribution in vivo limits further applications. Doxorubicin (DOX) is a commonly used antineoplastic drug, but its serious toxic side effects such as cardiotoxicity limit its further use. Therefore, it is very important to develop an effective and stable nano-carrier with bone tumor cell targeting effect and simultaneously capable of reducing toxic and side effects of the drug.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention aims to provide a cell-targeted polypeptide for treating bone tumor, a preparation method and a use thereof, which are used for solving the problem that the safety and the effectiveness of bone tumor cell-targeted drugs in the prior art cannot be considered at the same time.

To achieve the above objects and other related objects, the present invention includes the following technical solutions.

In a first aspect of the invention, there is provided an isolated polypeptide having a structure according to formula i:

Dm-X-Rn-C is shown as formula I,

in the formula I, m is the number of aspartic acid, and m is more than or equal to 6 and less than or equal to 10; n is the number of arginine, n is more than or equal to 6 and less than or equal to 10, and X is a polypeptide fragment which can be recognized and cut by MMP.

The polypeptide, wherein m is 8 and n is 8.

The polypeptide according to the above, wherein the amino acid sequence of X is selected from any one of the following:

KCQGWIGQPGCK SEQ ID NO.1，

CQGWIGQPGC SEQ ID NO.2，

QGWIGQPG SEQ ID NO.3，

CQGWIGQPGCK SEQ ID NO.4，

KCQGWIGQPG SEQ ID NO.5，

CQGWIGQPG SEQ ID NO.6，

GWIGQPGCK SEQ ID NO.7，

GWIGQP SEQ ID NO.8。

the application also discloses a composite particle modified by the polypeptide, wherein the composite particle is a polydopamine or polydopamine nano-composite particle modified by the polypeptide; the polydopamine nano-composite particle takes a metal organic framework as an inner core and takes polydopamine as an outer layer.

According to the composite particle, the size of the polydopamine nano-composite particle is 80-200 nm.

According to the composite particle, the metal organic framework is polydopamine and Mn²⁺And Co³⁺A hybrid material with intramolecular voids formed by coordination bond self-assembly.

According to the composite particle, the molar ratio of the polypeptide to the polydopamine or polydopamine nano-composite particle is (5-100): 1.

according to the composite particle, the preparation method of the polydopamine nano-composite particle comprises the following steps: mn (COO)₂·4H₂O、 K₃[Co(CN)₆]And dopamine hydrochloride in the presence of an alkaline solvent.

The composite particle as described above, wherein the solvent is ethanol or an ethanol aqueous solution.

The composite particles described above, Mn (COO)₂·4H₂O、K₃[Co(CN)₆]And the molar ratio of the dopamine hydrochloride to the dopamine hydrochloride is 1 (1-3): (1-3).

The invention also discloses a preparation method of the composite particle, and the polypeptide is mixed with the polydopamine or polydopamine nano-composite particle.

The application also discloses the application of the polypeptide and the composite particle as shown in the specification as bone tumor cell targeting drug carriers or in the preparation of bone tumor treatment drugs.

The application also discloses a carrier of the bone tumor cell targeted drug, wherein the carrier comprises one or two of the polypeptide and the composite particle. Due to metal ions such as Mn contained in the composite particles²⁺The MRI weighted signal of the bone tumor can be effectively enhanced, so that the polydopamine nanocomposite particle is an MRI contrast agent of the bone tumor, and is very suitable for photothermal therapy or photothermal-chemotherapy synergistic therapy of the bone tumor.

The application also discloses a bone tumor cell targeted pharmaceutical composition, which at least comprises:

an effective component for treating bone tumor and a carrier, wherein the carrier is modified by one or two of the polypeptide and the composite particle.

According to the pharmaceutical composition, the active ingredient for treating bone tumor is adriamycin.

The bone tumor in the present application includes primary bone tumor and secondary bone tumor. Primary bone tumors include: osteosarcoma, Ewing's sarcoma, fibrosarcoma, etc. Secondary bone tumors are tumors that metastasize to bone from tumors that grow elsewhere in the body. The method comprises the following steps: breast cancer, prostate cancer, liver cancer, lung cancer, kidney cancer, bladder cancer, and the like.

Compared with the prior art, the invention mainly has the following beneficial effects:

1. the prior art can only target bones or tumor cells independently, and the nanoparticles cannot fall off from the bones due to the single bone targeting, so that the potential toxicity exists. Stromal cell derived factor-1 and interleukin-6 produced by bone marrow stromal cells mediate homing, survival and proliferation of tumor cells, while integrin-mediated adhesion sequesters tumor cells in this protective environment. This "barrier" effect makes it difficult for individual tumor targeting molecules to further target bone tumor cells, and is prone to off-target. The oligomeric aspartic acid sequence at the front end of the bone tumor cell targeting peptide designed and synthesized by the invention can be firstly targeted to a bone damage interface of bone tumor, then the polypeptide fragment of middle X is sheared by matrix metalloproteinase MMP secreted by the bone tumor, and a cell-penetrating peptide fragment with the tail end consisting of oligomeric arginine is exposed, so that the cell-penetrating peptide improves the capacity of photothermal nanoparticles to enter the bone tumor cells, and finally the targeting of the bone tumor cells is realized. The polypeptide can successfully penetrate through a bone microenvironment to provide a 'barrier' for bone tumor cells, and a high-efficiency bone tumor cell targeting effect is realized.

2. The polypeptide is synthesized with cysteine at the tail end, and the cysteine contains a sulfhydryl group with reactivity, so that the bone tumor cell targeting peptide is easy to modify on the surfaces of various nanoparticles.

In a word, the polypeptide-modified polydopamine nanoparticle taking the metal organic framework as the core is loaded with the anti-tumor drug such as adriamycin, so that the targeting effect can be obviously enhanced, and the toxic and side effects of the drug can be reduced.

Drawings

Fig. 1 is a transmission electron microscope image of the polydopamine nanoparticle complex modified by the bone tumor targeting peptide obtained in example 1.

Fig. 2 shows the element distribution of the scanning electron microscope for the combination of the polydopamine nanoparticle composite modified by the bone tumor targeting peptide obtained in example 1 and hydroxyapatite.

Fig. 3 is a live imaging diagram of the polydopamine nanoparticle complex modified by the bone tumor targeting peptide obtained in example 1.

Fig. 4 is a nuclear magnetic resonance imaging diagram of the small animal of the polydopamine nanoparticle complex modified by the bone tumor targeting peptide obtained in example 1.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Before the present embodiments are further described, it is to be understood that the scope of the invention is not limited to the particular embodiments described below; it is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.

When numerical ranges are given in the examples, it is understood that both endpoints of each of the numerical ranges and any value therebetween can be selected unless the invention otherwise indicated. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition to the specific methods, devices, and materials used in the examples, any methods, devices, and materials similar or equivalent to those described in the examples may be used in the practice of the invention in addition to the specific methods, devices, and materials used in the examples, in keeping with the knowledge of one skilled in the art and with the description of the invention.

Unless otherwise indicated, the experimental methods, detection methods, and preparation methods disclosed herein all employ techniques conventional in the art of molecular biology, biochemistry, chromatin structure and analysis, analytical chemistry, cell culture, recombinant DNA technology, and related arts. These techniques are well described in the literature, and may be found in particular in the study of the MOLECULAR CLONING, Sambrook et al: a LABORATORY MANUAL, Second edition, Cold Spring Harbor LABORATORY Press, 1989and Third edition, 2001; ausubel et al, Current PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, New York, 1987and periodic updates; the series METHODS IN ENZYMOLOGY, Academic Press, San Diego; wolffe, CHROMATIN STRUCTURE AND FUNCTION, Third edition, Academic Press, San Diego, 1998; (iii) METHODS IN ENZYMOLOGY, Vol.304, Chromatin (P.M.Wassarman and A.P.Wolffe, eds.), Academic Press, San Diego, 1999; and METHODS IN MOLECULAR BIOLOGY, Vol.119, chromatography Protocols (P.B.Becker, ed.) Humana Press, Totowa, 1999, etc.

The applicant in the application provides an isolated polypeptide and unexpectedly finds that the polypeptide can be used for preparing a medicament for treating bone tumor related diseases, can enhance the targeting effect of the medicament, simultaneously reduces the using amount of active ingredients of the medicament, such as adriamycin, so as to reduce the toxic and side effects of the adriamycin, can be prepared and obtained by entrusting a polypeptide synthesis company to perform chemical synthesis, and the polypeptide has a polypeptide with an amino acid sequence shown as a formula I,

Dm-X-Rn-C is shown as formula I;

In the above, when the values of m and n are less than 6, there is no way to form electron aggregation, and the targeting ability is lost; above 10, the polypeptide chain is too long, self-assembling folds are produced, targeting is not favored, and the targeting effect is optimal for m and n being 8.

The polypeptide also contains an amino acid sequence that can be recognized and cleaved by MMP, and the amino acid sequence of fragment X of the polypeptide satisfying all the conditions described above is shown in Table 1.

TABLE 1

SEQ ID NO.	Amino acid sequence
		1	KCQGWIGQPGCK
2	CQGWIGQPGC
		3	QGWIGQPG
4	CQGWIGQPGCK
		5	KCQGWIGQPG
6	CQGWIGQPG
		7	GWIGQPGCK
8	GWIGQP

The polypeptide designed and synthesized by the invention is a bone tumor cell targeting peptide, the oligomeric aspartic acid sequence at the front end of the polypeptide can be firstly targeted to a bone damage interface of a bone tumor, then the middle X section is cut by MMP secreted by the bone tumor, and a cell-penetrating peptide fragment with the tail end consisting of oligomeric arginine is exposed, so that the capacity of photothermal nanoparticles entering the bone tumor cell is improved by the cell-penetrating peptide, and the targeting of the bone tumor cell is finally realized. The polypeptide can successfully penetrate through a bone microenvironment to provide a 'barrier' for bone tumor cells, and a high-efficiency bone tumor cell targeting effect is realized.

As the polypeptide has the characteristics, the applicant uses the polypeptide as a carrier of an effective component of a bone tumor cell targeting medicament. The polypeptide modified polydopamine or the polypeptide modified polydopamine nano-composite particles are adopted in photothermal therapy or chemotherapy or photothermal-chemotherapy synergistic therapy of bone tumor, and are used as carriers of effective components of bone tumor cell targeted drugs.

The polydopamine nano-composite particle takes a metal organic framework as an inner core and takes polydopamine as an outer layer. The size of the polydopamine nano-composite particles is 80-200 nm. Preferably, the metal organic framework is polydopamine and Mn⁴⁺And Co³⁺A hybrid material with intramolecular voids formed by coordination bond self-assembly.

The application discloses a bone tumor cell targeted pharmaceutical composition, which at least comprises: an effective component for treating bone tumor cells and a pharmaceutically acceptable carrier, wherein the carrier is modified by one or two of the polypeptide and the composite particles. More specifically, the pharmaceutical composition can be adriamycin and other known effective components for treating bone tumors.

The preparation method of the polydopamine nano-composite particle comprises the following steps: mn (COO)₂·4H₂O、K₃[Co(CN)₆]And dopamine hydrochloride in the presence of an alkaline solvent. The solvent can be selected according to actual needs, and can be ethanol or ethanol water solution. Preferably Mn (C)OO)₂·4H₂O、K₃[Co(CN)₆]And the molar ratio of the dopamine hydrochloride to the dopamine hydrochloride is 1 (1-3): (1-3).

To further verify the above findings and effects, the following experiments and characterization were performed in this application for further explanation.

The following examples of the present application specifically use polypeptides wherein m and n are both 8, such polypeptides being:

D₈-KCQGWIGQPGCK-R₈-C, noted BTTP.

Example 1

The preparation method of the polydopamine nanocomposite particles in the embodiment is as follows:

9.05mg Mn(COO)₂·4H₂o was dissolved in 10mL of 75% ethanol, 10mg of dopamine hydrochloride was added, and pH was adjusted to 8.5 with 1M ammonia water until dopamine hydrochloride was completely dissolved. The mixed solution is magnetically stirred for 30min at 30 ℃, and then 16.6mgK is added₃[Co(CN)₆]And 10mL of 75% ethanol, and the mixed solution was magnetically stirred at 30 ℃ for 24 hours. And centrifuging the reaction product at 12000rpm for 20min, and repeatedly centrifuging and washing the reaction product with deionized water for three times to obtain the poly-dopamine nano composite particles. (note as M @ P)

The preparation method of the bone tumor cell targeted drug carrier in the embodiment is as follows:

and mixing the polypeptide and the synthesized polydopamine nano-composite particles according to a molar ratio of 20:1, stirring the mixture in an aqueous solution with the pH value of 8.5 adjusted by 1M ammonia water for 24 hours, and centrifugally rinsing the mixture three times at 12000rpm to obtain the polypeptide-modified polydopamine nano-composite particles. (note as TM @ P)

The preparation method of the bone tumor cell targeted pharmaceutical composition in this embodiment is as follows:

and mixing the carrier with 0.1mg/mL adriamycin dimethyl sulfoxide solution, wherein the molar ratio of the polydopamine nano particles to the adriamycin is 1:2000, stirring the mixture in an aqueous solution for 24 hours, and centrifugally rinsing the mixture three times at 12000rpm to obtain the bone tumor cell targeted peptide-polydopamine nano composite particle compound loaded with the chemotherapeutic drug adriamycin. (note TM @ P/DOX)

Example 2

18.1mg Mn(COO)₂·4H₂o was dissolved in 10mL of 75% ethanol, 5mg of dopamine hydrochloride was added, and after the dopamine hydrochloride was completely dissolved, pH was adjusted to 8.5 with 1M ammonia water. Magnetically stirring the mixed solution at 30 deg.C for 30min, adding 8.3mgK₃[Co(CN)₆]And 10mL of 75% ethanol, and the mixed solution was magnetically stirred at 30 ℃ for 24 hours. And centrifuging the reaction product at 12000rpm for 20min, and repeatedly centrifuging and washing the reaction product with deionized water for three times to obtain the poly-dopamine nano composite particles. (note as M @ P)

The preparation method of the bone tumor cell targeted composite particle in the embodiment is as follows:

mixing the bone tumor cell targeting peptide and the polydopamine nano-composite particles in a molar ratio of 100:1, stirring the mixture in an aqueous solution with the pH value of 8.5 regulated by 1M ammonia water for 24 hours, and centrifugally rinsing the mixture three times at 12000rpm to obtain the polypeptide-modified polydopamine nano-composite particles. (note as TM @ P)

and mixing the carrier with 0.1mg/mL adriamycin dimethyl sulfoxide solution, wherein the molar ratio of the polydopamine nano particles to the adriamycin is 1:10000, stirring the mixture in an aqueous solution for 24 hours, and centrifugally rinsing the mixture three times at 12000rpm to obtain the bone tumor cell targeted peptide-polydopamine nano composite particle compound loaded with the chemotherapeutic drug adriamycin. (note TM @ P/DOX)

Example 3

The preparation method of polydopamine in this example is as follows:

40mg of dopamine hydrochloride was dissolved in 10mL of 75% ethanol, and after dopamine hydrochloride was completely dissolved, 1M ammonia was used to adjust the pH to 8.5. The solution was magnetically stirred at 30 ℃ for 24 h. And (3) centrifuging the reaction product at 12000rpm for 20min, and repeatedly centrifuging and washing the reaction product with deionized water for three times to obtain the poly-dopamine nano composite particles (marked as PDA).

the bone tumor cell targeting peptide and the polydopamine are mixed according to a molar ratio (20:1), stirred in an aqueous solution with the pH value of 8.5 adjusted by 1M ammonia water for 24 hours, and then centrifugally rinsed three times at 12000rpm to obtain the bone tumor cell targeting peptide modified polydopamine nanocomposite particles (marked as TP).

and (2) mixing the carrier with 0.1mg/mL adriamycin dimethyl sulfoxide solution, wherein the molar ratio of the polydopamine nano particles to the adriamycin is 1:2000, stirring the mixture in an aqueous solution for 24 hours, and centrifugally rinsing the mixture three times at 12000rpm to obtain the bone tumor cell targeting peptide-polydopamine nano composite particles (marked as TP/DOX) loaded with the chemotherapeutic drug adriamycin.

In order to verify the above-described technical effects, the applicant of the present application performed the following tests and characterization on the experimental materials in example 1.

(I) observing M @ P and TM @ P nano particles obtained by reaction through Transmission Electron Microscope (TEM)

Respectively adding 1 mu g of M @ P and TM @ P obtained by reaction into 1mL of deionized water for dispersion, after ultrasonic treatment for 1h, respectively dropwise adding 1 mu L of the diluent onto a copper net of an endoscope, and airing the solution for later use. The resulting M @ P and TM @ P nanoparticles were observed using a Transmission Electron Microscope (TEM) as shown in FIG. 1. As can be seen from FIG. 1, M @ P and TM @ P are uniform in size, cubic in shape, and have distinct MOF structures.

(II) in vitro simulation test, scanning electron microscope element distribution

The preparation method of the NM @ P sample is as follows:

by using D₈-KCPGGWQQIGCK-R₈the-C polypeptide is used as a control experiment, the polypeptide structure cannot be recognized by MMP, so that the polypeptide is a bone targeting MMP non-cleavable peptide and is marked as BTNP. BTNP was mixed with the M @ P nanocomposite particles synthesized in example 1 at a molar ratio of 20:1, stirred in an aqueous solution adjusted to pH 8.5 with 1M ammonia water for 24 hours, and then centrifugally rinsed three times at 12000rpm to obtain polypeptide-modified polydopamine nanocomposite particles. (note as NM @ P)

Incubating 100. mu. L M @ P, NM @ P and TM @ P, respectively, in aqueous solution with the hydroxyapatite tablets for 24h, wherein the concentration of the aqueous solutionThe degrees are all 100. mu.g/mL. Thereafter, the EDS elemental analysis image of the sample was observed by using SEM. In order to characterize the bone affinity of TM @ P, high crystallinity hydroxyapatite chips (the major inorganic component of bone) were used in this application for in vitro bone targeting experiments. Studies have shown that the erosive bone surface is composed primarily of highly crystalline hydroxyapatite, while the new bone interface is composed primarily of amorphous hydroxyapatite. Therefore, the adoption of the high-crystallinity hydroxyapatite sheet can better simulate the bone erosion interface of bone tumor in vitro. After incubating M @ P, NM @ P and TM @ P with the hydroxyapatite sheet for 24h respectively, EDS-mapping is used for characterizing the binding capacity of the hydroxyapatite sheet and the hydroxyapatite sheet, and specific characterization results are shown in figure 2. The surface of the NM @ P and TM @ P hydroxyapatite is combined with a large amount of Mn²⁺Significantly higher than the unmodified M @ P group, indicating that both BTNP and BTTP are bone-targeted.

(III) mouse experiment, in vivo imaging

MDA-MB-231 cells (2X 10 in 20. mu. LPBS)⁵Individual cells) were seeded into the luminal marrow of the tibia to generate an in situ bone tumor model. Bone tumor-producing mice were injected intravenously with near infrared fluorescent molecule labeled M @ P-Cy5.5(30.00mg/kg), TM @ P-Cy5.5(30.00mg/kg) and NM @ P-Cy5.5(30.00mg/kg), respectively, and imaged by small animal In Vivo (IVIS) 24h later. The mice were then sacrificed and bone tumors were isolated from the tibia. Bone tumors and tibia were also imaged by IVIS. The IVIS characterization results are shown in fig. 3. As can be seen in FIG. 3, both NM @ P-Cy5.5 and TM @ P-Cy5.5 detected a fluorescence signal at the tibial tumor, while M @ P-Cy5.5 did not. Further dissecting the tibial tumor, separating the tumor from the tibia, the fluorescence of TM @ P-Cy5.5 was distributed mainly at the bone tumor, while the fluorescence of NM @ P-Cy5.5 was distributed mainly at the tibia. Experimental results prove that the bone tumor cell targeting of BTTP is realized, but BTNP which can not be identified by MMP and then sheared does not have the bone tumor cell targeting.

Nuclear magnetic resonance imaging of small animal

M @ P, TM @ P and NM @ P (30.00mg/kg) were injected tail vein into tumor-bearing mice, respectively. MR images were taken on a Bruker 7.0T magnet equipped with Avance II hardware, equipped with 72mm quadrature transmit/receive coils, taken before and 24h after injection. The parameters for 7T MRI were: TR (repetition time) 750.0ms, TE (echo time) 12.6ms, echo 1/1, FOV 6.91/3.12cm, slice thickness 2mm, nex (average) 2mm, and matrix 256 × 116.

And verifying the bone tumor targeting property of BTTP, and using MRI for characterization. Mn²⁺Has MRI T1 contrast function. Bone-bearing tumor mice from the M @ P, NM @ P and TM @ P groups were examined by T1 modality MRI using a 7.0T MR scanner. T1 weighted MR was used for 24h images before and after intravenous M @ P, NM @ P and TM @ P, respectively. Analysis of the T1-weighted signal changes in the tumor-associated tibia showed (as in fig. 4) that NM @ P observed a significantly brighter T1-weighted signal at the tibia, while TM @ P observed a brighter T1-weighted signal at the tumor. There was no significant change in tumor-associated tibial signals before and after injection of M @ P. The result shows that the TM @ P serving as the MRI contrast agent for the bone tumor is obtained, and T1 weighted MRI signals of a mouse injected with the TM @ P are obviously enhanced, which shows that BTTP obviously enhances the bone tumor targeting of the nanoparticles.

Based on the above mechanism and experimental effect, the TP formed in embodiment 3 of the present application, as a drug carrier, has a good bone targeting and bone tumor targeting effect, due to the modification of the polypeptide having bone targeting and bone tumor targeting.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Sequence listing

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Claims

1. An isolated polypeptide having the structure of formula i:

Dm-X-Rn-C is shown as formula I,

2. The polypeptide of claim 1, wherein m is 8, n is 8;

and/or, the amino acid sequence of X is selected from any one of the following:

KCQGWIGQPGCK SEQ ID NO.1，

CQGWIGQPGC SEQ ID NO.2，

QGWIGQPG SEQ ID NO.3，

CQGWIGQPGCK SEQ ID NO.4，

KCQGWIGQPG SEQ ID NO.5，

CQGWIGQPG SEQ ID NO.6，

GWIGQPGCK SEQ ID NO.7，

GWIGQP SEQ ID NO.8。

3. a composite particle modified with the polypeptide of any one of claims 1 to 2, wherein the composite particle is a polydopamine or polydopamine nanocomposite particle modified with the polypeptide of any one of claims 1 to 2; the polydopamine nano-composite particle takes a metal organic framework as an inner core and takes polydopamine as an outer layer.

4. The composite particle according to claim 3, wherein the size of the polydopamine nanocomposite particle is 80 to 200 nm;

and/or the molar ratio of the polypeptide to the polydopamine or polydopamine nano-composite particles is (5-100): 1;

and/or the metal organic framework is polydopamine and Mn²⁺And Co³⁺A hybrid material with intramolecular voids formed by coordination bond self-assembly.

5. The composite particle according to any one of claims 3 to 4, wherein the preparation method of the polydopamine nanocomposite particle comprises the following steps: mn (COO)₂·4H₂O、K₃[Co(CN)₆]And dopamine hydrochloride in alkaline and organic formThe reaction takes place in the presence of a solvent.

6. A method of preparing a composite particle according to any one of claims 3 to 5, comprising mixing the polypeptide with polydopamine or polydopamine nanocomposite particles.

7. Use of the polypeptide according to any one of claims 1 to 2, the composite particle according to any one of claims 3 to 5 as a bone tumor cell-targeted drug carrier or in the preparation of a bone tumor treatment drug.

8. A carrier of a bone tumor cell targeted drug, wherein the carrier comprises one or two of the polypeptide of any one of claims 1 to 2 and the composite particle of any one of claims 3 to 5.

9. A bone tumor cell-targeted pharmaceutical composition, comprising at least:

an active ingredient for treating bone tumor and a carrier, wherein the carrier is one or two selected from the polypeptide of any one of claims 1 to 2 and the composite particle of any one of claims 3 to 5.

10. The pharmaceutical composition according to claim 9, wherein the effective component for treating bone tumor is doxorubicin.