CN112870355B

CN112870355B - Composite nano-porous platinum-based coordination polymer and preparation method and application thereof

Info

Publication number: CN112870355B
Application number: CN202110119691.7A
Authority: CN
Inventors: 张帆; 曹众; 吴英健; 冯力文
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University; Sun Yat Sen University Shenzhen Campus
Priority date: 2021-01-28
Filing date: 2021-01-28
Publication date: 2022-04-01
Anticipated expiration: 2041-01-28
Also published as: CN112870355A

Abstract

The invention discloses a composite nano-porous platinum-based coordination polymer and a preparation method and application thereof, the composite nano-porous platinum-based coordination polymer (nPPPCPs) provided by the invention has a core-shell structure, wherein the outer shell is a nano-porous platinum coordination polymer consisting of platinum ions and conjugated organic ligands, the inner core is a zero-valent inorganic platinum nano-particle containing small size, the prepared nPPPCPs have metal platinum centers with different valence states, have a special core-shell structure and can be used as a radiation sensitizer, the composite nano-porous platinum-based coordination polymer has the characteristics of good biocompatibility, low toxicity and the like, can specifically respond to a tumor acid microenvironment under low radiation dose, can deliver the inorganic platinum nano-particles to the deep part of a tumor in a graded delivery mode to kill tumor cells under low radiation dose, and adopts a one-step synthesis method with few steps, simple operation, and can be applied to deep delivery of tumor tissues and radiotherapy sensitization.

Description

Composite nano-porous platinum-based coordination polymer and preparation method and application thereof

Technical Field

The invention relates to the technical field of coordination polymers, in particular to a composite nano-porous platinum-based coordination polymer and a preparation method and application thereof.

Background

Cancer (malignancy) is one of the major threats to human health. At present, about 70% of cancer patients still adopt radiotherapy in the cancer treatment process due to the advantages of universality, local controllability, non-invasiveness and the like of radiotherapy. However, due to the special physicochemical properties of tumor tissues, the radiation dose is often increased or a sensitizer is often used to ensure the tumor treatment effect during the clinical treatment process. However, the indiscriminate damage of radiation beams to tumor cells and normal tissue cells greatly limits the application of radiation therapy, resulting in poor treatment efficacy, poor patient compliance, and the like. With the help of the development of the CT imaging technology and the computer technology, the damage to normal tissue cells is reduced by locally reducing the irradiation dose. However, the low sensitivity of some tumor cells (adenocarcinoma, squamous carcinoma, brain tumor, breast cancer, etc.) to radiation beams still greatly limits the therapeutic effect of radiotherapy. Therefore, the research and development of the medicine capable of realizing effective radiotherapy sensitization in tumor tissues is one of effective ways for solving the existing defects of clinical radiotherapy.

In recent years, researchers found that nanomaterials containing high atomic number (high Z) elements (such as gold, platinum, bismuth and the like) can be used as a radiation sensitizer to effectively deposit ray energy in tumor tissues so as to achieve a better radiation treatment effect. The mechanism of action of radiotherapy is: after the particles receive X-ray radiation, photoelectric effect and Auger electrons which have killing effect on cells are generated, and the intensity of the photoelectric effect is in positive correlation with the atomic number. In other words, the higher the atomic number of an element, the more radiant energy that can be deposited, the greater the ability to produce the photoelectric effect, at the same irradiation energy. In addition, the hypoxic environment of tumor tissue is a large factor affecting the effectiveness of radiation therapy. The phenomenon is more obvious because oxygen in cells is further lost due to the radiotherapy process. Platinum (Pt) is one of the high Z elements, and has an effect of enhancing the photoelectric effect. Under irradiation energy, platinum substances are adsorbed on DNA through static electricity, and the generation of auger electrons can be further promoted by the additional ionization generated by the high ionization section of the platinum substances, so that the capability of killing cells is improved. And inorganic platinum nanoparticles (Pt NPs) have been proven to be a substance that can effectively catalyze endogenous hydrogen peroxide to generate oxygen to slow down the radiotherapeutic resistance of tumor tissues. Therefore, the inorganic platinum nano-particles with the advantages of good biocompatibility, low toxicity, stability and the like gradually become a good choice for the radiotherapy sensitizer. But the small size (2-20 nm) of the nano-particles leads the nano-particles to be easily cleared by a metabolic system in vivo, and the effective radiotherapy sensitization effect is difficult to realize. At present, a multi-step assembly method or a metal sputtering deposition method is mostly adopted to attach small-sized platinum nanoparticles to a nano-carrier with larger size so as to improve the in-vivo circulation time of the nano-carrier. Both of these strategies, while effective in solving the in vivo enrichment problem due to size problems, often require multiple synthetic steps for the preparation process. Secondly, the content of the inorganic platinum nanoparticles in unit volume of the composite platinum nanoparticles obtained by the weak force effect connection mode is not high, so that the radiotherapy effect and the curative effect are poor. In addition, the properties of the composite nanoparticles are often determined by the monomers, and the multifunctional performance is limited. Therefore, it is very significant to explore a simple and economic synthesis method to prepare a nano sensitizer which can not only ensure the intrinsic characteristics and functions of the inorganic platinum nanoparticles, but also realize multi-functionalization.

In recent years, Porous Coordination Polymers (PCPs), also known as Metal-Organic Frameworks (MOFs), have attracted attention as a Coordination polymer with a three-dimensional pore structure because of its advantages of high porosity, large specific surface area, controllable pore structure size, good biocompatibility, and the like. In recent years, researchers have focused on the chemistry of high atomic number hafnium (Hf) ions. A series of radiotherapy sensitization nanoparticles (Biomaterials,2016,97, 1-9.; Nature Biomedical Engineering,2018,2,600-610.) such as Hf-TCPP, DBP-Hf and the like are successfully constructed by utilizing the characteristics of coordination chemistry of metal ions. The nano particles prepared from the porous coordination polymerization framework Materials (MOFs) with the carrier function can ensure the biocompatibility and the safety of the nano particles, and simultaneously skillfully utilize the chemical properties and the structural characteristics of the nano particles, and provide a new combined treatment strategy with radiotherapy sensitization effect in the aspect of tumor treatment. However, the in vivo targeting can be realized only by further modification of other polymers (such as PEG) on the surface, and the efficient generation of active oxygen and singlet oxygen at the tumor site cannot be realized under the low irradiation condition (0.5-5 Gy), so that the growth of the tumor cannot be effectively inhibited.

Disclosure of Invention

The invention aims to solve the technical problems that the existing radiotherapy sensitizer can realize in-vivo targeting only by further modification of other polymers on the surface and cannot realize high-efficiency generation of active oxygen and singlet oxygen at a tumor part under the condition of low irradiation, and provides a composite nano-porous platinum-based coordination polymer¹O₂) High efficiency, thereby inhibiting the growth of tumor.

It is still another object of the present invention to provide a method for preparing a composite nanoporous platinum-based coordination polymer.

It is yet another object of the present invention to provide the use of a composite nanoporous platinum-based coordination polymer.

The above purpose of the invention is realized by the following technical scheme:

a composite nano-porous platinum-based coordination polymer has a core-shell structure, wherein the core is inorganic platinum nano-particles containing zero valence, and the shell is a nano-porous platinum coordination polymer consisting of platinum ions and two conjugated organic ligands with acid sensitive groups.

The composite nano-porous platinum coordination polymers (nPPPCPs) provided by the invention have a core-shell structure, wherein the outer shell is a nano-porous platinum coordination polymer consisting of platinum ions and two conjugated organic ligands with acid-sensitive groups, the inner core is a zero-valent inorganic platinum nanoparticle containing small size, and metal centers with different valence states are obtained by utilizing the chemical characteristic that the platinum ions are easy to reduce, and the metals with different valence states can provide different physical and chemical properties, so that the nano-material is multifunctional (such as catalyzing the generation of singlet oxygen, having the capability of CT contrast agents, specifically killing liver cancer cells and the like), effectively releases high-concentration zero-valent inorganic platinum nanoparticles (Pt NPs) to the tumor part and deep part, improves the tumor hypoxia environment and improves the sensitivity of radiotherapy so as to achieve the aims of killing tumor cells, improving the effect of radiotherapy and treating cancers under low irradiation dose.

Preferably, the size of the composite nano-porous platinum-based coordination polymer is 180-250 nm.

More preferably, the size of the composite nano-porous platinum-based coordination polymer is 180-200 nm.

Preferably, the conjugated organic ligand with the acid-sensitive group is a triazine imine derivative and terephthalic acid, wherein the molecular structure of the triazine imine derivative is shown as the following formula (I):

the invention protects the preparation method of the platinum-based coordination polymer, which comprises the following steps:

dissolving the triazine imine derivative and terephthalic acid in an organic solvent, dissolving platinum salt in water, then uniformly mixing the two solutions, reacting at 85-100 ℃ for 10-16 hours, centrifuging to obtain a solid, washing, and drying to obtain the platinum-based coordination polymer.

The invention prepares the composite nano-porous platinum-based coordination polymer by a one-step synthesis method, two ligands of a triazine imine derivative and terephthalic acid and a coordination chemical property of platinum ions and a mode of supermolecule chemical self-assembly, wherein the ligand and platinum salt are used for preparing the composite nano-porous platinum-based coordination polymer, the composite nano-porous platinum-based coordination polymer has a core-shell structure, the core is inorganic platinum nanoparticles (Pt NPs) containing zero valence, and the shell is platinum ions (Pt NPs)²⁺) And two conjugated organic ligands with acid sensitive groups, wherein the platinum ions have chemical characteristics of easy reduction, and metal centers with different valence states can be obtained by regulating and controlling synthesis conditions.

Preferably, the molar ratio of the triazine imine derivative to the terephthalic acid is 1-2: 1.5 to 2.5.

Preferably, the platinum salt is K₂PtCl₄。

Preferably, the mass-volume ratio of the triazine imine derivative to the organic solvent is 1mg: 0.7-1 mL.

Preferably, the mass volume ratio of the platinum salt to the water is 2mg: 1-1.5 mL.

The invention protects the application of the platinum-based coordination polymer in the preparation of a nano radiotherapy sensitizer or a nano diagnosis and treatment agent.

A platinum-based nano radiotherapy sensitizer comprises the platinum-based coordination polymer.

Compared with the prior art, the invention has the beneficial effects that:

the composite nano-porous platinum-based coordination polymer (nPPCs) provided by the invention has a core-shell structure, wherein the outer shell is a nano-porous platinum coordination polymer consisting of platinum ions and a conjugated organic ligand, the inner core is a zero-valent inorganic platinum nanoparticle containing small size, the nPPCs have metal platinum centers with different valence states, the prepared nPPCs can be used as a radiotherapy sensitizer, due to the special core-shell structure, the nPPCs not only have the characteristics of good biocompatibility, low toxicity and the like, but also can specifically respond to a tumor acid microenvironment under low irradiation dose, can deliver the inorganic platinum nanoparticles (Pt NPs) to the deep part of a tumor in a graded delivery mode, effectively enrich the inorganic platinum nanoparticles in vivo, improve the radiotherapy sensitivity, improve the tumor oxygen-lacking environment, so as to achieve the purposes of killing tumor cells, improving the effect and treating cancers under low irradiation dose, the invention adopts a one-step synthesis method, has few steps and simple operation, and can be applied to the fields of tumor tissue deep delivery, radiotherapy sensitization and the like.

Drawings

FIG. 1 is a transmission electron microscope image of a composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 2 is a graph showing the particle size and potential of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 3 is a transmission electron microscope image of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention after dissociation at different pH.

FIG. 4 is a scanning electron microscope image of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention under an environment of pH 7.4.

FIG. 5 is an element distribution diagram of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention under an environment of pH 7.4.

FIG. 6 is a scanning electron microscope and an element distribution diagram of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention under an environment of pH6.5.

FIG. 7 is an X-ray photoelectron spectrum of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 8 is a diagram of the in vitro catalysis of hydrogen peroxide to generate oxygen by the composite nano-porous platinum-based coordination polymer prepared in example 1 of the invention.

FIG. 9 is an infrared spectrum of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 10 is a drawing showing nitrogen absorption of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 11 is a diagram of singlet oxygen evolution for the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 12 is a graph of in vitro cell viability of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 13 is a graph showing the in vitro cell radiosensitization effect of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 14 is a transmission electron microscope image and a corresponding partially enlarged transmission electron microscope image of the composite nanoporous platinum-based coordination polymer prepared in example 1 of the present invention.

FIG. 15 shows detection in living cells using singlet oxygen detecting SOSG fluorescent probes¹O₂And (4) generating.

Detailed Description

The present invention will be further described with reference to specific embodiments, but the present invention is not limited to the examples in any way. The starting reagents employed in the examples of the present invention are, unless otherwise specified, those that are conventionally purchased.

Example 1

A composite nano-porous platinum-based coordination polymer has a core-shell structure, wherein the core is inorganic platinum nano-particles containing zero valence, and the shell is a nano-porous platinum coordination polymer consisting of platinum ions, triazine imine derivatives and terephthalic acid.

The preparation method of the composite nano-porous platinum-based coordination polymer comprises the following steps:

dissolving triazine imine derivative ligand (1mol) and terephthalic acid (1.5mol) in dimethyl formamide (DMF), K₂PtCl₄(3.5mol) is dissolved in pure water, and the mass volume ratio of the triazine imine derivative ligand to DMF is 1mg:0.7 mL; k₂PtCl₄The mass volume ratio of the pure water to the pure water is 2mg:1 mL; the ultrasonic dispersion time is 15min, and the two solutions are fully mixed and dissolved and then placed in a sealed reaction kettle; placing the reaction kettle in an oven, heating to 85 ℃, reacting for 10 hours, and cooling to normal temperature; and (3) taking out the obtained solid in the reaction kettle, placing the solid in a centrifuge tube, washing the solid for 15min by dimethylformamide and pure water respectively for 3 times under the condition that the centrifugal parameters are 13000rpm, and the washing solvent is DMF, pure water or absolute ethyl alcohol, and drying the solid under vacuum to obtain black brown solid, namely the nPPPCPs.

Example 2

dissolving triazine imine derivative ligand (2mol) and terephthalic acid (2.5mol) in dimethyl formamide (DMF), K₂PtCl₄(7mol) is dissolved in pure water, and the mass volume ratio of the triazine imine derivative ligand to DMF is 1mg:1 mL; k₂PtCl₄The mass volume ratio of the pure water to the pure water is 2mg:1.5 mL; the ultrasonic dispersion time is 15min, and the two solutions are fully mixed and dissolved and then placed in a sealed reaction kettle; placing the reaction kettle in an oven, heating to 100 ℃, reacting for 16 hours, and cooling to normal temperature; and (3) taking out the obtained solid in the reaction kettle, placing the solid in a centrifuge tube, washing the solid for 15min by dimethylformamide and pure water respectively for 3 times under the condition that the centrifugal parameters are 13000rpm, and the washing solvent is DMF, pure water or absolute ethyl alcohol, and drying the solid under vacuum to obtain black brown solid, namely the nPPPCPs.

Comparative example 1

The comparative example is Hf-TCPP prepared from hafnium tetrachloride and organic ligand TCPP, and the preparation method comprises the following steps: fully dissolving hafnium tetrachloride and an organic ligand TCPP into an N, N-dimethylformamide organic solvent; reacting the mixed solution at 80 ℃ for 2 days; after the reaction is finished, the solution is cooled to room temperature, and then is washed by using a methanol mixed solvent of one percent of triethylamine and dried to obtain the corresponding nano particles.

Comparative example 2

This comparative example uses hafnium tetrachloride and the organic ligand 5,15-di (p-benzoato) -porphyrin (H)₂DBP) was prepared in the same manner as in comparative example 1 except that the organic ligand TCPP was replaced with the organic ligand 5,15-di (p-benzoato) -porphyrin (H)₂DBP)。

Performance testing

1. Physicochemical property and performance characterization of nano porous platinum coordination polymer nPPCPs

(1) Observing the morphology and the particle size of the nPPCs by a transmission electron microscope: and (3) taking 10 mu L of pure water sample solution, dropwise adding the pure water sample solution on a surface carbon coating copper net, and naturally air-drying at room temperature. And under the condition of 200KV voltage, the appearance, the particle size and the dispersion condition of the nano particles are observed by a transmission electron microscope. As can be seen from FIG. 1, the resulting nPPCs are spherical and have a particle size of about 200 nm.

From the scanning electron micrograph of the npcpcs nanoparticles (fig. 14), the magnification is graded and clearly visible: the nano-particles have different structures inside and outside, the outer layer is a polymer outer layer consisting of metal organic ligands and platinum ions, and the inner layer is formed by small-size zero-valent platinum nano-particles (Pt NPs).

(2) DLS/Zeta Potentiel assay: the particle size, the polydispersity and the Zeta potential of the npppcps nanoparticles were measured using a malvern particle sizer. As shown in FIG. 2, the hydrated particle size of the nPPCs is about 200nm, which is consistent with the observed TEM results, and the particle size distribution is more concentrated with good dispersibility.

(3) pH responsiveness and degradation of nPPCPs: the nPPCPs samples were dispersed in purified water at different pH values (a) pH7.4 and (b) pH6.5 for 24, 72, 120 hours on a shaker with parameters 14000rad/min on a shaker at 37 ℃ and the morphology was observed by transmission electron microscopy. As can be seen in fig. 3, npcpcs substantially maintain their structure unchanged under neutral conditions. In a simulated tumor tissue micro-acid environment with the pH value of 6.5, the morphology of the nanoparticles gradually disappears along with the prolonging of time, and it is clear that inorganic platinum nanoparticles (Pt NPs) with the zero-valent small size are gradually released due to the dissociation of an external structure. The results demonstrate that: the composite nano-porous platinum-based coordination polymer nPPPCPs capable of responding to spontaneous dissociation of an acidic environment and releasing inorganic platinum nanoparticles (Pt NPs) is successfully and efficiently prepared by a simple one-step synthesis method.

(4) And (3) observing the element distribution of the nPPCs under different pH environments by a scanning electron microscope: dispersing certain concentration of nPPPCPs in ultrapure water with pH value of 7.4 and 6.5 respectively, incubating for 3 days at 37 ℃ by a shaking table, and slowly dripping the sample on clean aluminum foil paper until the sample is naturally dried. The particle morphology was observed under a high-resolution field emission scanning electron microscope (Gemini500, Zeiss/Bruker), and the relative content of each element in the nPPCs was determined by X-ray energy spectroscopy (EDS) (FIGS. 4-5). The results demonstrate that: the results of the transmission electron microscope and the particle size analyzer are consistent, the particle size of the nPPCs in water with the pH of 7.4 is about 200nm, the particle size distribution is uniform, the EDS results preliminarily prove that C, O, N, Pt and Cl elements exist and are uniformly distributed, wherein the Al element is derived from an aluminum foil paper substrate in the sample preparation process and does not participate in the construction of an nPPCPs system. After 3 days of incubation of npcpcs nanoparticles in ultrapure water at pH6.5, particle lysis and release of small irregular particles was observed (fig. 6). EDS spectroscopy observed that: the element content of the large particles and the cracked small particles is changed, under the condition of simulating a tumor acid microenvironment, the nPPCs nano particles (box 1 of figure 6) are subjected to responsive cracking, loose carbon-based outer frameworks of the nPPCPs are reserved, the nano particles with high Pt density are gradually released (box 2 of figure 6), and the release of the pH responsive Pt NPs observed in a transmission electron microscope is verified. The Na element is derived from ions introduced by adjusting the pH of the co-incubation solvent and does not participate in the construction of the nPPCs system.

(5) X-ray photoelectron spectroscopy: taking an nPPCPs powder sample for XPS energy spectrum analysis, and determining the chemical element composition condition of the sample. The results demonstrate that: the particle contains elements such as C, O, N, Pt, Cl and the like (figure 7a), and the method preliminarily shows that a plurality of different components participate in the construction of a system. Further peak resolution of Pt element confirms that two valence states of Pt (0) and Pt (II) exist simultaneously in the nanoparticle system (the Pt (0) peak is split into 4f in FIG. 7b_7/271.33eV and 4f_5/274.63 eV; pt (II) peak split of 4f_7/272.73eV and 4f_5/276.03eV), the ratio of the Pt (0) to the Pt (II) contents was found to be about 1:2 by peak integration.

(6) Capacity of the nPPCs particles in catalyzing hydrogen peroxide to generate oxygen in vitro: preparing 1mg/mL of sample mother liquor and 1mM of H by using deoxygenated pure water (argon gas is introduced after boiling for 3H by pure water and then introducing 10 min)₂O₂Mother liquor, stirring the sample mother liquor in deoxygenated water uniformly (500rad/min), adding H₂O₂The mother liquor brought the whole system to a sample gradient concentration of 0, 25, 50, 75, 100, 125, 150, 200 μ M (Pt content concentration) while starting measurement every 10 seconds using a dissolved oxygen meter. The results, shown in fig. 8a, demonstrate that: nPPCPs nanoparticles even at 100. mu.M PtUnder the content concentration, the oxygen gas can be generated to be close to 20mg/L in only 3 minutes, which is 2 times of the effect of the composite platinum nano particles of the same type. The result of the high-efficiency and rapid oxygen generation proves that the nano-particle has the capability of effectively catalyzing hydrogen peroxide to generate oxygen and has the potential of improving hypoxic environment in tumors. In addition, H can be monitored by UV-visible absorption spectroscopy₂O₂Characteristic absorbance of (A) to detect H₂O₂Decomposition of (3). In particular, concentration gradients of nPPPCPs with 10mM H were used₂O₂Incubation for 10min, monitoring its absorbance at 202nm every 30s to characterize H₂O₂Decomposition effect under catalytic action of nPPPCPs. (FIG. 8b) this result is consistent with the oxygen production results measured by the dissolved oxygen meter, further verifying the ability of the nPPPCPs nanoparticles to catalyze hydrogen peroxide efficiently.

(7) Determination of npcpcs particles by infrared absorption spectroscopy: and (3) placing 2-3 mg of nPPCs solid powder into a microscope infrared instrument for infrared absorption spectrum analysis of the substance. (FIG. 9) by comparative analysis with two organic ligands, namely, a triazine imine derivative (ligand L1) and terephthalic acid, which are synthetic raw materials, it can be found that: the absorption peak measured in the npppcps particles almost agreed with the group absorption peak of the triazine imine derivative (ligand L1) and terephthalic acid. Wherein the thickness is 1600cm^-1Here, an imine group absorption peak (C ═ N) is clearly visible. At 1700cm^-1The absorption peak (C ═ O) of the terephthalic acid carbonyl group disappeared due to successful complexation of COOH with the metal platinum ion. The above evidence indicates that: the nPPPCPs particles are composed of two organic ligands of triazine imine derivative (ligand L1) and terephthalic acid.

(8) Nitrogen adsorption test nPPCPs particle surface area and pore size: about 100-150 mg of the nPPCs material is taken, and the surface area and the pore size of the nPPCs particles are analyzed by using a full-automatic gas adsorption analyzer. According to the test result of the nitrogen adsorption experiment, the BET surface area of the nPPCs material is 27.9535m 2/g. The material has a certain mesoporous structure, and the aperture is 2.45 nm. (FIG. 10)

(9) Chemical probe 4-nitroso-N, N-dimethyllanaline (rno) determination of singlet oxygen production: samples of certain concentrations of nPPCPs were prepared as aqueous suspensions. And 25. mu.M of RNO and 10. mu.M of L-histidine were added thereto. The mixed solution was transferred to a centrifuge tube and nPPCPs samples (0, 10, 25 and 50 μ M) were given corresponding X-ray doses (0, 1, 2, 4, 8 Gy). The absorption spectrum of the solution was measured using an ultraviolet-visible spectrophotometer. (FIG. 11a) the difference in the absorbance of the RNO peak at 439nm [ Delta (OD) ] was determined by subtracting the reading in the sample curve from the control (no irradiation) curve and knowing the singlet oxygen producing capacity of the sample. (FIG. 11b) the results of the experiment show that: the nPPCs nano-particles have the capability of converting oxygen into singlet oxygen under the stimulation of X-rays, and the capability is in positive correlation with the concentration of the nPPCs nano-particles. The capacity of the nPPCs nano-particles for generating active oxygen in vitro provides a certain guarantee for further killing tumor cells.

(10) Intracellular singlet oxygen of tumor 4T1 ((II))¹O₂) Generating

Detection in living cells with singlet oxygen detecting SOSG fluorescent probes¹O₂And (4) generating. 4T1 cells were seeded into a 3.5cm petri dish and cultured for 24h, then the original medium was replaced with fresh medium containing 1. mu.M SOSG. After incubation for 30min, cells were washed three times with PBS and excess SOSG was removed. Cells were incubated with PBS, 50. mu.M nPPCPs for 8h, and then washed three times with PBS to remove excess nanoparticles. Cells were irradiated with X-rays at a dose of 4 Gy. Laser confocal microscopy (CLSM) revealed the production in different groups of living cells by measuring the intracellular green fluorescence¹O₂The content of (a). (FIG. 15) the results of the experiment show that: under the low irradiation dose of 4Gy, only the nPPCs nanoparticles are respectively detected to be obvious green fluorescence by a laser confocal microscope, which indicates that a large amount of active oxygen substances capable of killing tumor cells are generated¹O₂。

2. In vitro cytotoxicity evaluation of nanoporous platinum coordination polymers (nPPCPs)

A mouse breast cancer cell line 4T1 and human umbilical vein endothelial cells HUVES with the density of 2000-2500 cells/hole are selected to be inoculated on a 96-hole cell culture plate, after incubation for 24 hours, 10 mu L of PBS suspension of nPPPCPs with different concentration gradients is added, and a blank control group is set at the same time. After further incubation for 24 hours, cell activity was measured by MTT method using a microplate reader. (FIG. 12) the results of the experiment show that: within 24 hours, under the intervention of the nPPCs nano-particles, the survival rates of human normal cells Huvec and 4T1 are both 80-100%, which shows that the nano-particles have no obvious killing effect, and further proves the safety of the nano-particles.

3. In-vitro cell radiotherapy sensitization effect of nano porous platinum coordination polymer (nPPCPs)

(1) Cytotoxicity: murine breast cancer cell line 4T1 cells were selected and seeded at a density of 200 cells/well in 96-well cell culture plates. After 24 hours of incubation, 10. mu.L of 50. mu.M (concentration here refers to the content of metallic Pt) suspension of nPPCs, nPPCPs-pH6.5 (npPCPs nanoparticles were incubated in PBS at pH6.5 for 3 days) in PBS was added thereto and a blank control group was set at the same time. After another 8 hours of co-incubation, the cells were given the corresponding X-ray dose (0, 0.5, 1, 2, 4, 6 Gy). After the irradiation, the cells were returned to the incubator and cultured for 72 hours. Subsequently, the cell activity was measured by MTT method using a microplate reader. (FIG. 13a) the results of the experiment show that: under the same irradiation dose, the nPPCs nano particles improve the killing capability on 4T1 tumor cells, and have an ideal radiotherapy sensitization effect. Meanwhile, the nano particle treated in advance in the acid environment, namely the nPPPCPs-pH6.5, releases more inorganic platinum nano particles (Pt NPs) capable of realizing sensitization effect due to the self acid response capability, and has stronger tumor cell killing capability and better radiotherapy sensitization effect.

(2) Clone analysis: the radiosensitization of the nPPCs nanoparticles is examined through a clone analysis experiment. Murine breast cancer cell line 4T1 cells were seeded at a density of 10 ten thousand cells/well in cell culture dishes. After 24 hours of incubation, 50 μ M (concentration here refers to the content of metallic Pt) of npPCPs nanoparticles were added thereto and the corresponding blank control group was set at the same time. After another 8 hours of co-incubation, the cells were given the corresponding X-ray dose (0, 1, 2, 4, 8 Gy). After irradiation, the corresponding samples were digested and counted. Samples were irradiated for 0, 1, 2, 4Gy, reseeded in 6-well plates at 200 cells per well; the 8Gy irradiated sample was then seeded with 1000 cells. And putting the re-inoculated cells into the incubator again for culturing for 5-10 days. Prior to cell colony counting, the corresponding samples were fixed and stained with 0.5% crystal violet in methanol. Cell populations with more than 50 cells observed were counted as effectively viable populations. Cell survival score ═ number of surviving colonies/(number of seeded cells × seeding efficiency). The mean cell survival score was obtained from six parallel experimental groups. According to the experimental results, under the condition that the nPPCs nano-particles participate, the killing effect of the X-rays with different doses on the tumor cells is stronger than that of a control group. (FIG. 13b) this result is sufficient to show that the nPPCs nanoparticles can be widely applied to radiotherapy sensitizers.

Compared with the two nano particles prepared in the comparative examples 1 and 2, the Hf-TCPP can realize intravenous injection and tumor targeting function only through further surface modification, and the steps are more complicated; in the aspect of radiation sensitization, 4-6 Gy of dose is needed to realize the in-vitro and in-vivo effects, namely, high dose is needed to be used, and the harm to a human body is increased. The Hf-DBP nano particles can realize irradiation sensitization with low dose of 0.5-4 Gy in the aspect of irradiation sensitization, but the nano particles can only adopt an intratumoral injection mode, the nano particles are difficult to realize uniform dispersion and size uniformity under the condition of no surface modification, and the steps are more complicated. In addition, the two kinds of nanoparticles have shortcomings in catalyzing hydrogen peroxide to generate oxygen and improving tumor hypoxia capability, which is caused by low content of heavy atoms Hf in the nanoparticles.

The composite nano-porous platinum-based coordination polymer nPPCs provided by the invention can ensure that the obtained nanoparticles have uniform size due to the characteristics of the structure of the nanoparticles, well realize in-vivo targeting, and do not need to rely on further modification of other polymers (such as PEG) on the surface. Secondly, because the nano-particle has high content of platinum particles, the irradiation sensitization with low dose is realized and the tumor hypoxia is effectively improved. And the preparation method has few steps and is easy to operate.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The composite nano-porous platinum-based coordination polymer is characterized by having a core-shell structure, wherein the core is inorganic platinum nano-particles containing zero valence, and the shell is a nano-porous platinum coordination polymer consisting of platinum ions and two conjugated organic ligands with acid sensitive groups;

the conjugated organic ligand with the acid-sensitive group is triazine imine derivative and terephthalic acid, wherein the molecular structure of the triazine imine derivative is shown as the following formula (I):

2. the platinum-based coordination polymer according to claim 1, wherein the composite nanoporous platinum-based coordination polymer has an average particle size of 180 to 250 nm.

3. The method for producing a platinum-based coordination polymer according to claim 1 or 2, characterized by comprising the steps of:

4. The preparation method according to claim 3, wherein the molar ratio of the triazine imine derivative to terephthalic acid is 1-2: 1.5 to 2.5.

5. The method according to claim 3, wherein the platinum salt is K₂PtCl₄。

6. The preparation method according to claim 3, wherein the mass-to-volume ratio of the triazineimine derivative to the organic solvent is 1mg:0.7 to 1 mL.

7. The preparation method according to claim 3, wherein the mass-to-volume ratio of the platinum salt to water is 2mg: 1-1.5 mL.

8. Use of the platinum-based coordination polymer according to claim 1 or 2 in the preparation of a nano radiosensitizer or a nano diagnostic agent.

9. A platinum-based nano radiosensitizer, comprising the platinum-based coordination polymer according to claim 1 or 2.