CN110755640A

CN110755640A - Preparation method and application of gold-platinum composite nano diagnosis and treatment agent

Info

Publication number: CN110755640A
Application number: CN201911001361.7A
Authority: CN
Inventors: 李春霞; 王曼; 吕光磊; 陈晴; 王冬梅
Original assignee: Zhejiang Normal University CJNU
Current assignee: Zhejiang Normal University CJNU
Priority date: 2019-10-21
Filing date: 2019-10-21
Publication date: 2020-02-07
Anticipated expiration: 2039-10-21
Also published as: CN110755640B

Abstract

The invention provides a preparation method and application of a gold-platinum composite nano diagnosis and treatment agent, which is Au synthesized by using L-proline as a chelating agent and L-ascorbic acid as a reducing agent₂Pt nanoparticles and Au obtained by post-modification thereof₂Pt-PEG-PS (PS: photosensitizer) and application thereof. Au coating₂The Pt-PEG-PS nano-particle has catalase activity and peroxidase activity, and can over-express hydrogen peroxide (H) in tumors under the weak acid condition₂O₂) Reaction in situ generation of oxygen (O)₂) And highly toxic active oxygen hydroxyl radical (. OH)Thereby playing the roles of overcoming hypoxia, enhancing photodynamic effect and killing cancer cells. Au coating₂The Pt alloy can also realize CT imaging, photoacoustic imaging, photothermal imaging and other multi-mode imaging simultaneously, and realize the integration of combined treatment and diagnosis and treatment.

Description

Preparation method and application of gold-platinum composite nano diagnosis and treatment agent

Technical Field

The invention belongs to the field of nano materials, and particularly relates to a gold-platinum composite nano diagnosis and treatment agent Au₂A preparation method and application of Pt-PEG-Ce 6.

Background

The number of cancer patients increases year by year in the world, seriously threatens the health of people, and the traditional treatment method limits the effective treatment of the cancer due to the inherent limitations. Photodynamic therapy and photothermal therapy have attracted extensive attention of researchers due to their advantages of being minimally invasive, low-toxicity, highly selective, and the like. However, the treatment also faces some challenges, such as tissue penetration depth of light and hypoxia of tumor region, which limit the therapeutic effect of the treatment. Therefore, it is important to develop a system for overcoming tumor hypoxia and realizing the combination of multiple treatment methods.

In recent years, nano-enzyme has attracted attention because of its characteristics of high catalytic efficiency, stable structure, low price, etc. and the characteristics of nano-materials. Au and Pt nano materials in the noble metal nano enzyme are favored by researchers due to higher in vivo and in vitro biocompatibility, good light stability and higher photo-thermal conversion efficiency. The mixed bimetal nano material has better optical and chemical properties than single-element nano particles, simultaneously has catalase activity and peroxidase activity, and can be used for over-expressing hydrogen peroxide (H) in tumors under the weak acid condition₂O₂) Reaction in situ generation of oxygen (O)₂) And highly toxic active oxygen hydroxyl radical (. OH), thereby acting to overcome hypoxic species, enhance photodynamic effects and kill tumor cells. The AuPt alloy can also realize CT imaging, photoacoustic imaging, photothermal imaging and other multi-mode imaging simultaneously, and realizes diagnosis and treatment integration.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: providing a process for preparing Au₂A synthesis method of Pt-PEG-Ce6 nano particles. The nanoparticles can be used for photothermal therapy and photodynamic therapyAnd for photothermal, photoacoustic and CT imaging.

The invention adopts the following technical scheme for solving the technical problems:

the preparation method of the gold-platinum composite nano diagnosis and treatment agent provided by the invention synthesizes Au by using L-proline as a chelating agent and L-ascorbic acid as a reducing agent₂Pt nanoparticles.

The Au layer₂The atomic ratio of Au to Pt in the Pt nanoparticles is 2:1, the particle size is 25-80 nanometers.

The method comprises the following steps:

(1) using L-proline, ascorbic acid, sodium hydroxide, HAuCl₄And H₂PtCl₆Solution synthesis of Au₂A Pt alloy;

(2) synthesis of Au₂Pt-PEG-Ce6 nanoparticles: utilizing the coordination capability of sulfydryl and Au, Pt₂Pt surface modification SH-PEG-NH₂Then covalently connecting Ce6 according to condensation reaction of amino and carboxyl to finally obtain Au₂Pt-PEG-Ce6 nanoparticles.

The invention uses L-proline as a chelating agent to synthesize Au with good dispersibility in water₂The particle size of the Pt alloy is 25-80 nanometers, and the Pt alloy meets the endocytosis size of cells.

Au in the invention₂The ultraviolet visible absorption of the Pt alloy can reach a near infrared region, and experiments prove that the Pt alloy can be used for 808 nanometer photothermal treatment.

Au in the invention₂The Pt alloy has catalase activity, and experiments prove that the Pt alloy can react with hydrogen peroxide to generate oxygen.

Au in the invention₂The Pt alloy has peroxidase activity, and experiments prove that the Pt alloy can react with hydrogen peroxide to generate high-toxicity hydroxyl radicals.

The invention uses SH-PEG-NH₂Modified Au₂Pt alloy is covalently connected with chlorin e6(Ce6) on the basis, and experiments prove that in a hypoxic environment, 650nm laser irradiates Au₂Pt-PEG-Ce6 nanoparticles can generate singlet oxygen. The dosage of Ce6 is 40-100mg g^-1。

The present invention is a method of killing tumor cells using photodynamic therapy and photothermal therapy and nanoparticles to generate hydroxyl radicals in situ.

The invention can realize three-mode imaging, including photothermal imaging, photoacoustic imaging and CT imaging.

Compared with the prior art, the invention has the following main advantages:

(1) the synthesis method is simple and environment-friendly, and the reaction is carried out at room temperature;

(2) synthesized Au₂Pt-PEG-Ce6 with over-expressed H in solid tumor microenvironment₂O₂In situ reaction to produce O₂It can overcome tumor hypoxia environment, enhance photodynamic effect, and can be combined with H₂O₂OH generated by in situ reaction and two active oxygen species (in vivo)¹O₂And. OH) while synergistically killing tumor cells in combination with photothermal therapy;

(3) the covalent connection of the photosensitizer Ce6 can enhance the stability of the photosensitizer and avoid the premature release of the photosensitizer in a complex organism;

(4) the three-mode imaging (CT imaging, photoacoustic imaging and photothermal imaging) can be realized simultaneously, and powerful support is provided for drug tracking. Based on the advantages and good biocompatibility, the nano platform has good killing effect on tumors, and provides a new hope for effective treatment of cancers.

Drawings

FIG. 1 is Au₂XRD pattern of Pt.

FIG. 2a is Au₂Transmission electron microscopy image of Pt, FIG. 2b is Au₂The elements of Pt map the image.

FIG. 3A and FIG. 3B are Au respectively₂Pt and Au₂Hydrated particle size plot of Pt-PEG-Ce 6.

FIG. 4 is Au₂Pt、Au₂Pt-PEG-NH₂And Au₂Zeta potential diagram of Pt-PEG-Ce 6.

FIG. 5 is Au₂Pt and Au₂UV-visible absorption pattern of Pt-PEG-Ce 6.

In FIG. 6, FIG. 6a shows different concentrations of Au2Pt-PEG-Ce6 at 808nm (1W cm)^-25min) temperature under irradiationThe temperature change curve is shown in FIG. 6b, which is the temperature change curve of Au2Pt-PEG-Ce6 (400. mu.g mL-1) under laser irradiation (808nm, 5min) with different powers.

FIG. 7 shows Au concentrations₂Pt-PEG-Ce6 added 3.2mM H₂O₂(pH 7) graph of oxygen concentration in solution as a function of time.

FIG. 8 is Au₂Pt-PEG-Ce6(100μg mL^-1) 2mM H was added to the solution₂O₂And 0.04mM TMB, absorption peak of TMB as a function of time.

FIG. 9 is Au₂Pt-PEG-Ce6(50μg mL^-1) Addition of H₂O₂(2mmol L^-1) Then at reaction time of 0, 5, 10min and H alone₂O₂(2mmol L^-1) ESR spectrum of (d).

FIG. 10 shows Au respectively₂Pt-PEG-Ce6，H₂O₂Mixing the solution with Au₂After DPBF is added into the Pt-PEG-Ce6 solution, the absorption peak of the DPBF changes along with time under the irradiation of a 650nm laser.

FIG. 11 shows Au concentrations₂Pt and Au₂Effect of Pt-PEG-Ce6 on the survival of L929 cells and Hela cells.

FIG. 12 is Au₂Cytotoxicity of Pt-PEG-Ce6 on Hela cells at various pHs.

FIG. 13 shows Au treated differently₂Cytotoxicity of Pt-PEG-Ce 6.

FIG. 14 shows CT images (axial, coronal, and orthostatic VR images) of mice before and after injection of material.

FIG. 15 shows in situ injection of saline and Au₂Photothermographic images of Pt-PEG-Ce 6.

FIG. 16 shows in situ injection of saline and Au₂Photo-acoustic imaging of Pt-PEG-Ce 6.

FIG. 17 is a graph showing the change in body weight and tumor size of the mice within 14 days. In which FIG. 17a is a graph showing the change in body weight of a mouse within 14 days, and FIG. 17b is a graph showing the change in tumor size of a mouse within 14 days.

Detailed Description

The invention provides a preparation method of a gold-platinum composite nano diagnosis and treatment agent and a preparation method thereofThe application is that Au is synthesized by using L-proline as a chelating agent and L-ascorbic acid as a reducing agent₂Pt nanoparticles and Au obtained by post-modification thereof₂Pt-PEG-PS (PS: photosensitizer) and application thereof. Au coating₂The Pt-PEG-PS nano-particle has catalase activity and peroxidase activity, and can over-express hydrogen peroxide (H) in tumors under the weak acid condition₂O₂) Reaction in situ generation of oxygen (O)₂) And highly toxic active oxygen hydroxyl radical (. OH), thereby acting to overcome hypoxia, enhance photodynamic effect and kill cancer cells. Au coating₂The Pt alloy can also realize CT imaging, photoacoustic imaging, photothermal imaging and other multi-mode imaging simultaneously, and realize the integration of combined treatment and diagnosis and treatment.

The method comprises the following steps:

(1) dissolving L-proline in water to obtain a solution A;

(2) adding a chloroauric acid solution and a chloroplatinic acid solution into the solution A to obtain a solution B;

(3) adjusting the pH value of the solution B by using sodium hydroxide to obtain a solution C;

(4) dropwise adding L-ascorbic acid into the solution C to obtain a solution D;

(5) and separating the solution D to obtain a precipitate, and finally dispersing the precipitate in water to obtain the gold-platinum composite nano diagnosis and treatment agent.

By following in Au₂The present invention is described in detail by connecting the photosensitive molecule Ce6 to the Pt surface, but the embodiment of the present invention is not limited thereto.

Example 1:

synthesis of Au₂Pt nanoparticles: 33mmol L of^-1L-proline was dissolved in 10mL of water. Then 2mmol L^-1HAuCl of₄And H₂PtCl₆The solution was added to the mixture. After adjusting the solution pH to 9, 6.7mmol L was added dropwise^-1The ascorbic acid solution of (2) was stirred at room temperature for 20 minutes, centrifuged at high speed (14000rpm/min, 5min), washed 3 times with deionized water, and dispersed in 10mL of water.

To verify that the synthesized nanoparticles are Au₂Pt alloy, analysis thereof by X-ray diffractometer, X-rayRepresentative diffraction peaks in the line diffraction pattern appear at 38.34 °, 44.44 °, 64.86 ° and 77.88 °, which originate from face centered cubic lattice (fcc) Au₂The (111), (200), (220) and (311) faces of the Pt alloy, with these peaks between elemental Au and elemental Pt, show its alloy properties (fig. 1). Can prove the successful synthesis of Au₂Pt nanoparticles. Au was observed by a Transmission Electron Microscope (TEM)₂The Pt nanoparticles are spherical aggregates with a diameter of about 42 ± 3 nm. The uniform distribution of Au and Pt atoms in the spherical aggregate can be seen through the energy dispersion x-ray spectrum of the high-angle annular dark field scanning transmission electron microscope and the element mapping image and the line scanning image thereof, and the atomic number ratio of Au atoms to Pt atoms is 2:1 (figure 2).

Example 2:

synthesis of Au₂Pt-PEG-Ce6 nanoparticles: 10mg of SH-PEG-NH₂Adding into the solution prepared in the example 1, stirring for 24 hours at room temperature to obtain Au₂Pt-PEG-NH₂The mixture was centrifuged at high speed, washed 3 times with water, and dispersed in 5mL of water.

Then 1mg of Ce6, 8mg of EDC and 12mg of NHS were dissolved in 5mL of DMF and reacted for 1 hour, and Au was added₂Pt-PEG-NH₂The reaction was carried out at room temperature for 24 hours. Centrifuging, collecting precipitate, and washing with water for 3 times to obtain Au₂Pt-PEG-Ce6 nanoparticles.

The results of post-test analysis of the nanoparticles prepared in the above examples are provided below.

(1) For synthesized Au₂Pt and Au₂The Pt-PEG-Ce6 nanoparticles were subjected to hydrated particle size analysis:

increasing from 57.03 nm to 70.89 nm as shown in fig. 3.

For synthesized Au₂Pt，Au₂Pt-PEG-NH₂，Au₂The Pt-PEG-Ce6 nanoparticles were subjected to Zeta potential analysis:

as shown in FIG. 4, Au₂Pt has a Zeta potential of-26.5 mV and SH-PEG-NH modified on its surface₂Then, the Zeta potential of the amino group exposed on the surface of the amino group rises to 10.6mV, and after covalent bonding of Ce6, the Zeta potential drops to-24.2 mV.

The two components areAll the precipitation shows Au₂Successful synthesis of Pt-PEG-Ce6 nanoparticles.

(2) For Au₂The Pt-PEG-Ce6 nanoparticles were subjected to UV-VIS absorption spectroscopy:

as shown in figure 5, the absorption can reach the near infrared region, and the nano-silver nano.

(3) For synthesized Au₂And (3) carrying out photothermal effect detection on the Pt-PEG-Ce6 nanoparticles:

different concentrations of Au₂Pt-PEG-Ce6 nanoparticles (0, 50, 100,200,300 and 400. mu.g mL)^-1) Placing in a centrifuge tube, and then using 808nm laser (1W cm)^-2) The irradiation was carried out for 5 minutes, the temperature change was monitored by an infrared thermal imager, and the temperature was recorded every 15 seconds. Then fixing Au₂The concentration of Pt-PEG-Ce6 nanoparticles was 400. mu.g mL^-1Varying the laser power (0.5, 0.75, 1W cm)^-2) And then monitoring and recording the temperature.

The results are shown in FIG. 6, along with Au₂The concentration of Pt-PEG-Ce6 is increased, and the temperature of the solution is increased; the laser power is then varied and as the laser power increases, the solution temperature increases.

(4) Detecting catalase-like activity:

different concentrations of Au₂Pt-PEG-Ce6(0, 20, 40, 60, 80 and 100. mu.g mL)^-1)、H₂O₂(3mmol L^-1) Was added to 3mL of a phosphate buffer solution (pH 7), and the concentration of dissolved oxygen in the solution was measured with a dissolved oxygen meter.

The results are shown in FIG. 7, where only H is present₂O₂When existing, the oxygen concentration in the solution has no obvious change, and the change is accompanied with Au₂Increased concentration of Pt-PEG-Ce6, H₂O₂The oxygen production rate is gradually increased, which shows that Au₂Pt-PEG-Ce6 has catalase-like activity and can be used for treating H overexpressed in tumors₂O₂Reaction to produce O₂Thereby improving tumor hypoxia and enhancing photodynamic effect.

(5) Detecting the peroxidase-like activity:

detection of Au Using TMB as a substrate₂Peroxidase activity of Pt, reacting Au₂Pt-PEG-Ce6(100μg mL^-1)、H₂O₂(1mmol L^-1) And TMB (0.02mmol L)^-1) Sequentially adding into 3mL phosphate buffer solution (pH 4.5), and observing absorption change of TMB at 652nm with ultraviolet-visible spectrophotometer (peroxidase and H)₂O₂The reaction can change colorless TMB to blue oxTMB, with distinct absorption peaks observed at 370nm and 652 nm).

To 100. mu.g mL^-1Au₂1mM H was added to the Pt-PEG-Ce6 solution₂O₂And 0.02mM TMB, a distinct absorption peak of TMB was observed, and the change with time of the absorption peak of TMB is shown in FIG. 8, demonstrating that it has peroxidase-like activity.

(6) Carrying out electron spin resonance technical analysis on the nanoparticles:

Au₂Pt-PEG-Ce6(50μgmL^-1)，H₂O₂(2mmol L^-1) After adding the mixture to 2mL of PBS (pH 5), 5-dimethyl-1-pyrroline-N-oxide (DMPO, 25mM) was added, and an ESR spectrum was recorded at 0, 5, and 10min of the reaction, as shown in fig. 9, a four-line spectrum with an intensity of 1:2:2:1 was found at 5 minutes, and was more prominent at 10 minutes, indicating that more OH was generated as the reaction proceeded.

(7) Detection of singlet oxygen:

under the condition of oxygen deficiency, Au₂Pt-PEG-Ce6(50μg mL^-1)，H₂O₂(2mmol L^-1) Added to 3mL of PBS (pH 7) and then 1, 3-diphenylisobenzofuran (DPBF, 20 μ g mL) was added^-1) Using a 650nm laser (0.1W cm)^-2) Irradiating for 0,3, 6, 9, 12 and 15min, and respectively recording the absorption peak of DPBF at 420nm (the singlet oxygen can oxidize the DPBF to change the structure and reduce the absorption peak at 420 nm) by using an ultraviolet-visible spectrophotometer when the DPBF is irradiated for different time.

In order to simulate tumor hypoxia microenvironment, DPBF and Au are added₂Pt-PEG-Ce6 and H₂O₂Is added to with N₂DPBF is at 420nm under 650nm laser irradiation in PBS solution blown for a long timeThe absorption peak of (A) decreased with the increase of the laser irradiation time as shown in FIG. 10, demonstrating that Au was present₂Pt-PEG-Ce6 and H₂O₂Singlet oxygen can be generated under 650nm laser irradiation.

(8) Cell culture and detection of compatibility:

the L929 and Hela cells were placed in high glucose DMEM medium containing 1% (v/v) penicillin/streptomycin and 10% (v/v) Fetal Bovine Serum (FBS), and placed at 37 deg.C, 5% CO₂Culturing in an incubator. 8000L 929 or Hela cells per well were seeded into 96-well plates and used at different concentrations (0,100,200,300,400 and 500. mu.g mL)^-1) Of Au₂Pt or Au₂Pt-PEG-Ce6 in high glucose DMEM medium was incubated for 24 hours. Relative cell viability was determined by a standard 3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide (MTT) assay.

As shown in FIG. 11, Au was used without any treatment of the nanoparticles₂Pt and Au₂Pt-PEG-Ce6 has no obvious toxicity to L929 cells and Hela cells, and the in vitro biocompatibility is good.

(9)Au₂Pt-PEG-Ce6 cytotoxicity assay in vitro at different pH:

hela cells (8000 cells per well) were seeded into 96-well plates and incubated for 24 hours. With or without the addition of H₂O₂(100. mu.M) Au₂Pt-PEG-Ce6(0,100,200,300 and 400. mu.g mL)^-1). The pH of the medium was then adjusted to 7.35 and 6.75 by the addition of HCl (1M), respectively. Then, the cells were incubated at 37 ℃ with 5% CO₂The culture was further incubated for 24 hours. Finally, cell viability was assessed using the MTT assay. Au as shown in FIG. 12₂Pt-PEG-Ce6 has peroxidase activity in slightly acidic environment, and can react with H₂O₂OH is produced to kill the cells.

(10)Au₂In vitro cytotoxicity assay of Pt-PEG-Ce6 under different lights:

hela cells (8000 cells per well) were seeded into 96-well plates and incubated for 24 hours. Subsequently, Au was added₂Pt-PEG-Ce6(0,100,200,300 and 400. mu.g mL)^-1) Added to the plate at 37 ℃ with 5% CO₂Followed by incubation for an additional 4 hours.Replacing the original culture medium with fresh culture medium, respectively using 808nm laser (1W cm)^-2) Hela cells were irradiated for 10 minutes with 650nm laser (0.259 Wcm)^-2) Irradiation is carried out for 10 minutes or for 10 minutes by simultaneous irradiation with 808nm and 650nm laser light. Then, the cells were incubated at 37 ℃ with 5% CO₂The culture was further incubated for 24 hours. Finally, cell viability was assessed using the MTT assay.

As shown in fig. 13, the combined PTT and PDT treatment reduced Hela cell viability to around 12%, while PDT treatment and PTT treatment alone had cell viability of 55% and 34%, respectively. The effect of the combination therapy proved to be much better than that of the individual therapy.

(11) Computed tomography live imaging:

selecting female Balb/c mice of 6-8 weeks, carrying cervical cancer cells U14 in axillary left foreleg, and injecting 100 μ L (4mg mL) of nanoparticles synthesized in the embodiment in situ when the tumor grows to a proper size^-1) And then imaged using computed tomography techniques. Images before non-injection were taken as controls. As shown in FIG. 14, the synthesized nanoparticles can be used for CT imaging, and can be used as a CT imaging contrast agent in biological imaging.

(12) In vivo photothermal imaging:

selecting female Balb/c mice of 6-8 weeks, carrying cervical cancer cells U14 in axillary left foreleg, and injecting 100 μ L (4mg mL) of nanoparticles synthesized in the embodiment in situ when the tumor grows to a proper size^-1) Irradiating with 808nm laser (1 Wcm)²) Imaging with an infrared thermal imager while irradiating for 5 minutes, and taking the image before non-injection as a contrast. As shown in fig. 15, the nanoparticles synthesized in the example can be used for photothermal imaging and in biological imaging.

(13) In-vivo photoacoustic imaging:

selecting female Balb/c mice of 6-8 weeks, carrying cervical cancer cells U14 in axillary left foreleg, and injecting 100 μ L (4mg mL) of nanoparticles synthesized in the embodiment in situ when the tumor grows to a proper size^-1) The mouse is anesthetized and placed on an animal support, and then the mouse and the support are transferred into a multispectral tomography system (MSOT) imaging cabin for imagingThe image of saline injection was used as a control. As shown in fig. 16, the nanoparticles synthesized by the embodiment can be used for photoacoustic imaging and biological imaging.

(14) In vivo tumor inhibition experiments:

35 female Balb/c mice of 6-8 weeks were selected, the cervical cancer cells U14 were loaded in the axilla of the left anterior leg, when the tumors grew to a suitable size, the mice were randomly divided into 7 groups, the mice were treated with 808nm laser and 650nm laser after 12 hours by injecting physiological saline and the nanoparticles synthesized in example 2 into the caudal vein, and the weight and tumor size of the mice were recorded every other day.

The results are shown in figure 17, with some weight gain in each group of mice, indicating negligible toxicity of the materials of the examples. Tumor volume continued to increase in the control and the single laser irradiation groups, while the single material group was slightly suppressed. The single photothermal therapy and the photodynamic therapy have the effect of inhibiting the tumor, but the single treatment effect is poor, the tumor volume is slightly increased, and the combined photothermal and photodynamic therapy group can well inhibit the tumor growth.

The invention has the following characteristics:

1. one-step synthesis of Au₂Pt, and the synthetic method is simple and environment-friendly, and the solvent is water, and the reaction can be carried out at room temperature;

2. the photosensitizer Ce6 is covalently connected, so that the early leakage in a complex organism is avoided, and the damage to normal tissues is avoided;

3.Au₂Pt-PEG-Ce6 with over-expressed H in solid tumor microenvironment₂O₂The in-situ reaction can simultaneously generate O₂And OH, O₂Overcoming tumor hypoxia environment, enhancing photodynamic effect, and killing tumor cells in cooperation with photothermal therapy;

4. can be used as a three-mode imaging contrast agent (CT imaging, photoacoustic imaging and photothermal imaging).

The above-mentioned embodiments are preferred examples of the present invention, and are not intended to limit the present invention, and any modification, change, alteration or substitution made within the principle of the present invention is within the protection scope of the present invention.

Claims

1. A process for preparing the nano-class gold-platinum composition as diagnosing and treating agent includes such steps as using L-proline as chelating agent and L-ascorbic acid as reducer to synthesize Au₂Pt nanoparticles.

2. The method for preparing the gold platinum composite nano diagnostic agent according to claim 1, wherein Au is added₂The atomic ratio of Au to Pt in the Pt nanoparticles is 2:1, the particle size is 25-80 nanometers.

3. The method for preparing the gold platinum composite nano diagnostic and therapeutic agent according to claim 1 or 2, wherein the method comprises the following steps:

(1) dissolving L-proline in water to obtain a solution A;

(4) dropwise adding L-ascorbic acid into the solution C to obtain a solution D;

4. The method according to claim 3, wherein the atomic ratio of Au to Pt is 1: 1.

5. The process according to claim 3, wherein in the step (1), the concentration of the solution A is 33mmol L^-1。

6. The process according to claim 3, wherein in the step (4), the concentration of L-ascorbic acid in the solution D is from 6 to 7mmol L^-1(ii) a The reaction time of solution D was 20-60 minutes.

7. The production method according to claim 3, wherein the reaction temperature of the production method is room temperature.

8. The method for preparing the Au/Pt composite nano diagnostic and therapeutic agent according to any one of claims 1 to 4, wherein the synthesized Au is Au₂Pt nanoparticles with SH-PEG-NH modified on their surface₂Then connecting photosensitizer chlorin e6(Ce6) to obtain Au₂Pt-PEG-Ce6 nanoparticles.

9. The method for preparing the gold platinum composite nano diagnosis and treatment agent according to claim 8, wherein the amount of Ce6 is 40-100mg g^-1。

10. The method for preparing the gold platinum composite nano diagnosis and treatment agent according to claim 8, wherein the Au is₂Pt-PEG-Ce6 nanoparticles for use in a tumor combination therapy agent or a multimodal imaging agent.