Gold nanomaterials with characteristic absorption in near-infrared II region and their preparation method and application

Abstract

The present invention discloses a gold nanomaterial having characteristic absorption in the near-infrared II region, and its preparation method and application. The preparation method is specifically as follows: first, chloroauric acid and a first ligand, 3-mercaptopropionic acid, are stirred and reacted in an ice bath; a second ligand, β-mercaptoethylamine, is added and the stirring reaction is continued; sodium hydroxide is added to adjust the pH, and then a sodium borohydride reducing agent is added and the stirring reaction is continued. The material is obtained after purification. The fluorescence emission wavelength of the material falls in the near-infrared II region, and there is a clear characteristic absorption peak in the near-infrared II region. Lasers of a specific wavelength can induce it to produce reactive oxygen and photothermal effects. Therefore, the present invention can be applied to the combined photodynamic and photothermal treatment of tumors. The preparation method of the gold nanoclusters is simple, low-cost, and easy to industrialize. The near-infrared II window has deeper tissue penetration and less tissue scattering or absorption. The material has good application prospects in the field of combined treatment of deep-seated tumors.

Description

Technical Field

[0001] The present invention belongs to the field of functional optical nanomaterials, and specifically relates to a gold nanocluster modified with a dithiol ligand having characteristic absorption in the near-infrared II region, and a preparation method and application thereof. Background Art

[0002] Due to its high incidence and mortality, cancer has become a pressing concern for human health. Traditional treatments include surgical resection, chemotherapy, and radiotherapy. However, surgical resection cannot completely eliminate all tumor cells from the primary lesion, and external surgical intervention can easily lead to tissue defects, making spontaneous healing difficult. Furthermore, chemotherapy and radiotherapy require high doses of anticancer drugs and emit intense radiation, all of which can have significant side effects on human health. Compared to traditional treatments, light-mediated therapies can provide information about the body and provide treatment without being invasive, precisely targeted, and easy to use. Therefore, phototherapy has been widely considered as a cancer treatment in recent years. Light-mediated cancer therapies include photodynamic therapy and photothermal therapy. Photodynamic therapy utilizes photosensitizers to generate cytotoxic reactive oxygen species under light irradiation. These reactive oxygen species interact with tumor cells and damage them. Photothermal therapy utilizes the photothermal conversion of light into heat to generate a hyperthermal effect, killing tumor cells. Light-mediated therapies offer non-invasive, precise, and highly effective tumor cell destruction, making them a popular research topic in recent years.

[0003] Current research on light-mediated cancer therapy primarily focuses on the near-infrared I window (NIR I, 650-950 nm), with relatively little research on the near-infrared II window (NIR II, 1000-1700 nm). Compared to NIR I, NIR II light has a longer wavelength, deeper tissue penetration (3-5 cm), and less tissue scattering or absorption. Furthermore, NIR II offers higher signal-to-noise ratios and resolution than NIR I for imaging. In tumor therapy, biological tissues have a higher tolerance to NIR II light, increasing the maximum permissible skin exposure, which facilitates improved phototherapy. Currently studied nanomaterials for NIR II light-mediated therapy are primarily novel organic optical agents, semiconductor polymer nanoparticles, and a few inorganic nanoparticles. However, these materials still have limitations. For example, while organic materials can achieve combined PDT and PTT, they are complex to synthesize, are large in size, have low tissue penetration, and exhibit poor biocompatibility. Accumulation in the body can cause harm. The limitation of most inorganic nanomaterials is that the PDT-PTT combined treatment system usually requires a combination of photosensitizers and photothermal agents, resulting in complex structure and synthesis. Materials that can cooperate with PDT-PTT treatment have failed to achieve treatment in the NIRⅡ region. Studies have shown that when using NIRⅡ light-mediated PDT or PTT treatment alone, the tumor will recur within a certain period of time. The combined treatment of PDT and PTT has the best effect and can effectively eliminate tumor cells while avoiding tumor recurrence. Therefore, the design and development of a nanomaterial with a simple structure, easy synthesis, small size, good biocompatibility, good photothermal stability, obvious absorption in the NIRⅡ region, and the ability to cooperate with PDT and PTT treatment is of great significance for the non-invasive, precise and efficient treatment of tumors.

[0004] With the rapid development of nanoscience and technology, nanoparticles are widely used in the field of biomedicine. Studies have found that gold nanoclusters with precise structures 25 SR 18 Modified with the single ligand captopril (Capt), they can generate singlet oxygen and photothermal effects under 808nm laser irradiation, resulting in a significant therapeutic effect on cutaneous squamous cell carcinoma. Gold nanoclusters (AuNCs) have the advantages of ultra-small size, surface ligand modifiability, controllable optical properties, good photostability, and biocompatibility, showing great potential in bioimaging, disease diagnosis, and tumor treatment. Therefore, by modifying their surface ligands, designing and developing a gold nanomaterial with significant absorption in the NIR II region to achieve NIR II light-mediated PDT-PTT combined therapy is of great significance for the efficient treatment of cancer. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of existing technologies, the present invention provides gold nanomaterials with characteristic absorption in the near-infrared II region, as well as methods for their preparation and application. Through dual-ligand modification and ligand ratio control, the gold nanomaterials provided by the present invention exhibit near-infrared II absorption properties and exhibit both photodynamic and photothermal effects under irradiation with a near-infrared II laser at a wavelength of 1064 nm. Therefore, this bis-thiol ligand-modified gold nanomaterial can be used for combined photodynamic and photothermal therapy of tumor cells.

[0006] The present invention is achieved through the following technical solutions.

[0007] A gold nanocluster with characteristic absorption in the near-infrared II region 25 SR 18 The preparation method comprises the following steps:

[0008] (1) At low temperature, chloroauric acid and the first ligand 3-mercaptopropionic acid (MPA) are stirred in a solvent to react;

[0009] (2) adding the second ligand β-mercaptoethylamine (CA) and stirring the reaction;

[0010] (3) adding sodium hydroxide to adjust the pH of the reaction system;

[0011] (4) adding sodium borohydride as a reducing agent and continuing to stir the reaction;

[0012] (5) After the reaction is completed, the concentrated sample is purified by ultrafiltration at low temperature and stored in a refrigerator (4°C).

[0013] Preferably, the solvent in step (1) is deionized water.

[0014] Preferably, the molar concentration ratio of the chloroauric acid to the total amount of the thiol ligand in steps (1) and (2) is 1:2; the molar concentration ratio of the first ligand MPA to the second ligand CA is 4:1; the molar concentration ratio of the sodium hydroxide to the chloroauric acid in step (3) is 60:1; and the molar concentration ratio of the reducing agent to the chloroauric acid in step (4) is 2.3:1.

[0015] Preferably, in step (1), the stirring reaction time of chloroauric acid and MPA in an ice bath is 1-2 hours; in step (2), the stirring reaction time after adding CA is 30 minutes; in step (3), the stirring reaction time after adding sodium hydroxide to adjust the pH to 12 is continued for 30 minutes; and in step (4), the stirring reaction time after adding the reducing agent sodium borohydride is continued for 21 hours. The temperature during the above reaction process is 4° C. and the rotation speed is 750 rpm.

[0016] Preferably, the ultrafiltration purification in step (5) is to remove unreacted substrate and concentrate the solution after the stirring reaction by centrifugation using an ultrafiltration tube. The ultrafiltration purification process temperature is 4°C, the rotation speed is 3750 rpm, the pore size of the ultrafiltration tube membrane is 10 kDa, the ultrafiltration centrifugation time is 15 min, the number of ultrafiltration washes is 6, the solvent added for washing is deionized water, and the ultrafiltration concentration is performed once after the washing is completed; the pH of the sample obtained after the ultrafiltration purification process is close to 7.

[0017] Preferably, the gold nanoclusters Au prepared by the above preparation method have characteristic absorption in the near-infrared II region. 25 SR 18 The gold nanomaterial is an aggregated nanoparticle, the particle size of a single gold nanoparticle is 1.3-1.9nm, and the precise structure is Au 25 MPA 11 CA7, the gold nanomaterial has obvious characteristic absorption in the near-infrared II region, and the characteristic absorption peak wavelength is in the range of 1050nm-1090.

[0018] Preferably, the use of the gold nanomaterial having characteristic absorption in the near-infrared II region in the preparation of a photosensitizer comprises the following steps:

[0019] The prepared gold nanomaterial with characteristic absorption in the near-infrared II region is mixed with the capture agent, irradiated with laser, and the generation of ROS is detected by electron spin resonance spectrometer (ESR).

[0020] Preferably, the trapping agents are hydroxyl radical (·OH) trapping agents: 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and singlet oxygen ( 1 O2) capture agent: 2,2,6,6-tetramethylpiperidine (TEMP), laser wavelength is 1064 nm, and irradiation time is 20 min.

[0021] The use of the gold nanomaterial having characteristic absorption in the near-infrared II region in the preparation of a photothermal agent comprises the following steps:

[0022] The prepared concentrated sample of gold nanomaterial with characteristic absorption in the near-infrared II region was diluted to a certain concentration with deionized water, irradiated with laser light, and the temperature change of the sample with irradiation time was monitored using a thermal camera.

[0023] Preferably, the concentration of the diluted gold nanomaterial with characteristic absorption in the near-infrared II region is 10-100 μM, the laser wavelength is 1064 nm, and the laser power is 0.25-1.00 W / cm 2 , the illumination time was 5 min, and the temperature was recorded every 10 s.

[0024] Furthermore, a concentrated sample of the gold nanomaterial with characteristic absorption in the near-infrared II region was diluted to a certain concentration and irradiated with laser light. A thermal camera was used to monitor the temperature change of the sample over the irradiation time. After the laser irradiation was stopped, the thermal camera was used to monitor the temperature change of the sample as it cooled. This step was repeated three times. The absorption and emission spectra of the gold nanoclusters were also monitored before and after laser irradiation.

[0025] Preferably, the concentration of the gold nanomaterial with characteristic absorption in the near-infrared II region is 100 μM, the laser wavelength is 1064 nm, and the laser power is 0.75 W / cm 2 , the illumination time was 4 min, the cooling time was 16 min, and the temperature was recorded every 10 s.

[0026] The gold nanomaterial synthesized in the present invention has the advantages of good biocompatibility, low toxicity, good photothermal stability, etc., and can be used in the preparation of photosensitizer-photothermal agent. At the same time, the material has obvious characteristic absorption in the near-infrared region II window. After irradiation with a laser with a wavelength of 1064nm, it can simultaneously generate reactive oxygen and photothermal effects. Therefore, the gold nanomaterial has great application prospects in the field of photodynamic-photothermal combined treatment of tumors.

[0027] Compared to commonly used PDT-PTT combination therapy materials, the gold nanoclusters described in this invention do not require the use of photosensitizers or photothermal agents; they can achieve PDT-PTT combination therapy on their own. They also offer advantages such as a simple structure, good stability, low toxicity, and excellent biocompatibility. The gold nanoclusters are simple to prepare, low-cost, and readily scalable for industrial production. Because the near-infrared II window offers deeper tissue penetration and reduced tissue scattering or absorption, this material holds great promise for applications in the combined treatment of deep-seated tumors.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] (1) The gold nanoclusters synthesized by the present invention have characteristic absorption in the near-infrared II region, and the synthesis process is simple, the cost is low, and it is easy to industrialize and produce.

[0030] (2) The gold nanoclusters with characteristic absorption in the near-infrared II region synthesized by the present invention have good biocompatibility, low toxicity, and good photothermal stability.

[0031] (3) The gold nanoclusters synthesized in the present invention have characteristic absorption in the near-infrared II region and can simultaneously produce reactive oxygen species and photothermal effects under irradiation with a laser of a wavelength of 1064 nm. Therefore, photodynamic-photothermal synergistic therapy can be achieved without the need for additional combination of photosensitizers or photothermal agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Absorption spectrum of .

[0033] Figure 2 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Emission spectrum of .

[0034] Figure 3 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Absorption spectrum changes with the change of the dual ligand ratio.

[0035] Figure 4 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Absorption spectrum changes with the extension of reaction time of the first ligand MPA.

[0036] Figure 5 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Absorption spectrum changes with the extension of reaction time of the second ligand CA.

[0037] Figure 6 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 The absorption spectrum changes with the reaction time after adding reducing agent and the normalized intensity diagram at a wavelength of 920nm.

[0038] Figure 7 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 The absorption spectrum changes with the extension of storage time.

[0039] Figure 8 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Accompanying transmission electron microscopy (TEM) images.

[0040] Figure 9 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Particle size statistics chart.

[0041] Figure 10The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 1 25 SR 18 Electrospray ionization mass spectrometry (ESI-MS) diagram.

[0042] Figure 11 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 2 25 SR 18 The intensity change of hydroxyl radical (·OH) after irradiation with a laser at a wavelength of 1064 nm for 20 min.

[0043] Figure 12 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 2 25 SR 18 After irradiation with 1064 nm laser for 20 min, singlet oxygen ( 1 O2) intensity changes.

[0044] Figure 13 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 3 25 SR 18 Temperature variation with increasing 1064nm laser irradiation time at the same sample concentration (100uM) and different laser power densities.

[0045] Figure 14 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 3 25 SR 18 At the same laser power density (0.75W / cm 2 ), Temperature variation diagram with increasing 1064 nm laser irradiation time at different sample concentrations.

[0046] Figure 15 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 3 25 SR 18 At 1064 nm laser (0.75 W / cm 2 ) Photothermal temperature change diagram after cooling to room temperature after irradiation for 4 minutes.

[0047] Figure 16 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 3 25 SR 18 Linear correlation plot of cooling time and negative natural logarithm of driving force temperature in photothermal experiments.

[0048] Figure 17 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 4 25 SR 18Photothermal stability during three cycles of 1064 nm laser heating-cooling.

[0049] Figure 18 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 4 25 SR 18 In three 1064nm laser (0.75W / cm 2 ) Absorption spectra before and after the heating-cooling cycle (sample diluted 10 times).

[0050] Figure 19 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 4 25 SR 18 After 1064nm laser (0.75W / cm 2 ) Emission spectra before and after heating-cooling cycles (sample diluted 10 times).

[0051] Figure 20 The present invention provides a flow chart for the preparation of gold nanoclusters that absorb in the near-infrared II region and a principle diagram for the preparation of photosensitizers and photothermal agents. DETAILED DESCRIPTION

[0052] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0053] In the following specific examples, the chloroauric acid and β-mercaptoethylamine involved were purchased from Shanghai Mairui Chemical Technology Co., Ltd., 3-mercaptopropionic acid was purchased from Aladdin Biochemical Technology Co., Ltd., sodium hydroxide was purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd., and sodium borohydride was purchased from Chengdu Kelon Chemical Reagent Factory. The instruments used to observe the properties of gold nanoclusters with characteristic absorption in the near-infrared II region and their in vitro applications include a Shimadzu UV2600 UV-visible spectrophotometer equipped with an integrating sphere (Japan), a PerkinElmer fluorescence / phosphorescence / luminescence photometer (LS-55) (USA), a Thermo Fisher field emission transmission electron microscope (Talos F200x) (USA), a Bruker TIMS-TOF mass spectrometer equipped with an electrospray ionization source (Germany), and a FLIR C5 thermal imager.

[0054] Example 1

[0055] Gold nanoclusters Au with characteristic absorption in the near-infrared II region 25 SR 18 The preparation steps are as follows (taking 10 mL as an example):

[0056] Under ice conditions, add 5.2 μL of 1.9 M chloroauric acid solution to a 20 mL clear screw-cap glass bottle containing 5.2 mL of deionized water and stir at 750 rpm. While continuing to stir, add 3.2 mL of 5 mM 3-mercaptopropionic acid (MPA) solution, the first ligand, and stir for 2 hours. Then, add 0.4 mL of 5 mM β-mercaptoethylamine (CA) solution, the second ligand, and continue stirring for 30 minutes. Then, add 600 μL of 1 M sodium hydroxide solution and stir for 30 minutes. Finally, add 200 μL of freshly prepared sodium borohydride solution (43 mg / 10 mL, dissolved in 0.2 M NaOH) dropwise and continue the reaction on ice for 21 hours.

[0057] After the reaction, the mixture was washed and purified with deionized water at 4°C and 3750 rpm to remove unreacted substrate. Ultrafiltration and centrifugation were repeated 6 times for 15 minutes, and the target product was finally concentrated and stored in a refrigerator at 4°C until use. Figure 1 is the absorption spectrum of the target product, Figure 2 Its emission spectrum.

[0058] This embodiment has gold nanoclusters Au with characteristic absorption in the near-infrared II region. 25 SR 18 The preparation of is the optimal synthesis reaction conditions:

[0059] Figure 3 It is a gold nanocluster with characteristic absorption in the near-infrared II region. 25 SR 18 The absorption spectrum changes with the change of the dual ligand ratio. As shown in the figure, when the dual ligand ratio MPA:CA is 1.6:0.4 or 4:1, the characteristic absorption peak in the near-infrared region is most obvious.

[0060] Figure 4 It is a gold nanocluster with characteristic absorption in the near-infrared II region. 25 SR 18 The absorption spectrum changes with increasing reaction time of the first ligand, MPA. As shown, the MPA reaction time has little effect on the optimal synthesis of the final target product. To achieve the optimal absorption peak, the MPA reaction time was set to 2 hours to ensure the most complete reduction of chloroauric acid by the ligand.

[0061] Figure 5 It is a gold nanocluster with characteristic absorption in the near-infrared II region. 25 SR 18 The absorption spectrum changes with the extension of the second ligand CA reaction time. As shown in the figure, 30 minutes of CA reaction is the optimal length.

[0062] Figure 6 It is a gold nanocluster with characteristic absorption in the near-infrared II region.25 SR 18 The absorption spectrum changes with the addition of reducing agent and the normalized intensity at 920 nm. As shown in the figure, the optimal reaction time is 21 hours.

[0063] The gold nanoclusters Au prepared in this embodiment have characteristic absorption in the near-infrared II region. 25 SR 18 Nature of:

[0064] (1) Stability when stored at 4°C

[0065] Take 4 μL of a 1000 μM concentrated sample and dilute it to 400 μL with deionized water. The molar concentration of the diluted sample is 10 μM. Freshly prepare dilutions of the same concentration at different time points and measure their absorption spectra using a UV-Vis spectrophotometer.

[0066] Figure 7 It is a gold nanocluster with characteristic absorption in the near-infrared II region. 25 SR 18 As shown in the figure, the absorption spectrum of gold nanoclusters Au with characteristic absorption in the near-infrared II region 25 SR 18 It has good storage stability at 4°C.

[0067] (2) Morphology and particle size

[0068] Figure 7 It is a gold nanocluster with characteristic absorption in the near-infrared II region. 25 SR 18 The transmission electron microscopy image of the synthesized gold nanoclusters Au with characteristic absorption in the near-infrared II region was analyzed by particle size analysis software (Nano Measurer 1.2.5). 25 SR 18 The results are as follows Figure 8 As shown, the particle size is 1.3-1.9 nm.

[0069] (3) Precise structure

[0070] Figure 9 It is a gold nanocluster with characteristic absorption in the near-infrared II region. 25 SR 18 The ESI-MS results obtained in negative ion mode. As shown in the figure, the gold nanoclusters Au modified with the dithiol ligand have characteristic absorption in the near-infrared II region. 25 SR 18 The distribution ratio of the above 18 ligands is 11-7, that is, the precise structure of the synthesized gold nanoclusters is Au 25 MPA11 CA7.

[0071] Example 2

[0072] Example 2 The implementation scheme of using gold nanoclusters with characteristic absorption in the near-infrared II region to prepare photosensitizers is as follows:

[0073] The prepared gold nanoclusters (300 μM) with characteristic absorption in the near-infrared II region were mixed with ·OH capture agents DMPO and 1 The O2 capture agent (TEMP) was mixed evenly and irradiated with a laser of 1064 nm for 20 min to detect the OH and 1 Production of O2. Figure 11 It is a gold nanocluster with characteristic absorption in the near-infrared II region. 25 SR 18 The intensity change of hydroxyl radical (·OH) after irradiation with a laser at a wavelength of 1064 nm for 20 min. Figure 12 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 2 25 SR 18 After irradiation with 1064 nm laser for 20 min, singlet oxygen ( 1 As shown in the figure, gold nanoclusters with characteristic absorption in the near-infrared II region can produce ·OH and 1 O2 and other active oxygen species.

[0074] Example 3

[0075] Example 3 The implementation scheme of using gold nanoclusters with characteristic absorption in the near-infrared II region to prepare a photothermal agent is as follows:

[0076] (1) Determination of laser power density in the preparation of photothermal agents using gold nanoclusters with characteristic absorption in the near-infrared II region

[0077] The prepared concentrated sample of gold nanomaterials with characteristic absorption in the near-infrared II region was diluted to 100 μM with deionized water, 400 μL per sample, and then the power densities were 0.25, 0.50, 0.75, and 1.00 W / cm 2 The sample was irradiated with a 1064 nm laser for 5 min. During the irradiation process, the temperature change of the sample with the extension of the irradiation time was monitored by a thermal camera, and the temperature was recorded every 10 s.

[0078] Figure 13 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 3 25 SR 18The temperature change diagram with the extension of 1064nm laser irradiation time at the same sample concentration (100uM) and different laser power densities. As shown in the figure, at the same sample concentration, with the increase of laser power density, the temperature change of the sample increases after the same laser irradiation time. Considering 1. When the heat treatment temperature is too low (<48°C), it will cause high expression of heat shock protein, which repairs heat-denatured protein, and ultimately leads to enhanced heat resistance of tumor cells, affecting the treatment effect. 2. When the heat treatment temperature is too high (>60°C), it will cause enzyme inactivation and protein denaturation, and the cells will instantly and irreversibly die rapidly, which will affect normal cells, causing inflammation and cancer metastasis. 3. During the treatment of living tumors, biological skin tissue will absorb part of the heat, affecting the treatment effect. 4. Excessive power density will cause damage to living skin. Therefore, 0.75W / cm 2 is the optimal laser power density.

[0079] (2) Determination of the concentration of gold nanoclusters with characteristic absorption in the near-infrared II region for the preparation of photothermal agents

[0080] The prepared gold nanomaterials with characteristic absorption in the near-infrared II region were diluted to 10, 30, 60, and 100 μM with deionized water, 400 μL for each sample, and then the wavelength was 1064 nm and the power density was 0.75 W / cm 2 The laser was irradiated for 5 minutes. The temperature change of the sample with the extension of irradiation time was monitored by a thermal camera, and the temperature was recorded every 10 seconds. The same volume of deionized water (0uM) was used as a blank control.

[0081] Figure 14 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 3 25 SR 18 At the same laser power density (0.75W / cm 2 ), temperature changes with increasing 1064nm laser irradiation time at different sample concentrations. As shown in the figure, at the same laser power density, increasing sample concentration leads to a greater temperature change after the same laser irradiation time. Based on comprehensive considerations, 100 μM was selected as the gold nanomaterial concentration for the photothermal experiment.

[0082] (3) Calculation of the photothermal conversion efficiency (PCE) of gold nanoclusters with characteristic absorption in the near-infrared II region for the preparation of photothermal agents

[0083] The prepared gold nanomaterial with characteristic absorption in the near infrared II region was diluted to 100 μM, 400 μL with deionized water. The wavelength was 1064 nm and the power density was 0.75 W / cm 2The laser irradiated the sample for 4 minutes, then stopped irradiation and allowed the sample to cool to room temperature. A thermal camera was used to monitor the temperature changes of the gold nanoclusters during the heating and cooling process of the photothermal agent, recording the temperature every 10 seconds.

[0084] Figure 15 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 3 25 SR 18 At 1064 nm laser (0.75 W / cm 2 ) irradiated for 4 minutes and then cooled to room temperature. The photothermal temperature change diagram was processed to obtain gold nanoclusters Au with characteristic absorption in the near-infrared II region. 25 SR 18 The linear correlation diagram of the cooling time and the negative natural logarithm of the driving force temperature in the photothermal experiment is as follows: Figure 16 According to the light-to-heat conversion efficiency formula, it is calculated that the gold nanoclusters Au with characteristic absorption in the near-infrared II region in Example 3 25 SR 18 The photothermal conversion efficiency η is 38.6%.

[0085] Example 4

[0086] In the experiment of detecting the photothermal stability of gold nanoclusters with characteristic absorption in the near-infrared II region, the concentrated sample of gold nanomaterials with characteristic absorption in the near-infrared II region was first diluted to 100uM and 400uL, and the absorption spectrum of the gold nanomaterials before laser irradiation was detected using a UV-visible spectrophotometer and a fluorescence photometer. 2 The sample was irradiated with a laser for 4 minutes. A thermal camera was used to monitor the temperature changes of the gold nanoclusters over time, recording the temperature every 10 seconds. After irradiation was stopped, the gold nanoclusters were allowed to cool to room temperature, during which time the thermal camera continued to monitor the temperature changes, recording the temperature every 10 seconds. This laser heating-cooling cycle was repeated three times. After the gold nanoclusters cooled to room temperature, the absorption and emission spectra of the gold nanomaterials after laser irradiation were measured using a UV-visible spectrophotometer and a fluorescence photometer.

[0087] Figure 17 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 4 25 SR 18 Photothermal stability during 3 cycles of 1064nm laser heating-cooling. As shown in the figure, gold nanoclusters Au have characteristic absorption in the near-infrared II region. 25 SR 18 The temperature can rise to 66.2-68.8℃ in three laser heating-cooling cycles. Figure 18The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 4 25 SR 18 In three 1064nm laser (0.75W / cm 2 ) Absorption spectra before and after heating-cooling cycle (sample diluted 10 times). As shown in the figure, gold nanoclusters Au have characteristic absorption in the near-infrared II region. 25 SR 18 After three laser heating-cooling cycles, it still shows obvious characteristic absorption in the near-infrared II window (1050nm). Figure 19 The gold nanoclusters Au with characteristic absorption in the near infrared II region in Example 4 25 SR 18 After 1064nm laser (0.75W / cm 2 ) Emission spectra before and after the heating-cooling cycle. As shown in the figure, gold nanoclusters Au have characteristic absorption in the near-infrared II region. 25 SR 18 After three laser heating-cooling cycles, the fluorescence properties were still good (the sample was diluted 10 times). The above results all indicate that the gold nanomaterial has good photothermal stability.

[0088] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a gold nanomaterial having characteristic absorption in the near-infrared II region, characterized in that: The following steps are involved: (1) In an ice bath, chloroauric acid and the first ligand 3-mercaptopropionic acid (MPA) were stirred in deionized water; (2) Add the second ligand β-mercaptoethylamine (CA) and continue stirring the reaction; (3) Add sodium hydroxide to adjust the pH to 12; (4) Add sodium borohydride as a reducing agent and stir to react; (5) After the reaction is completed, Au is purified by ultrafiltration at low temperature 25 MPA 11 CA 7； In steps (1) and (2), the molar concentration ratio of the chloroauric acid to the total amount of the thiol ligand is 1:2, wherein the molar concentration ratio of the first ligand MPA to the second ligand CA is 4:1; The gold nanomaterial is a gold nanocluster with a particle size of 1.3-1.9 nm and a precise structure of Au 25 MPA 11 CA7; The gold nanomaterial has obvious characteristic absorption in the near-infrared II region, and the characteristic absorption peak wavelength is at 1050-1090nm.

2. The method for preparing the gold nanomaterial having characteristic absorption in the near infrared II region according to claim 1, characterized in that: In step (3), the molar concentration ratio of sodium hydroxide to chloroauric acid is 60:1; and in step (4), the molar concentration ratio of the reducing agent to chloroauric acid is 2.3:

1.

3. The method for preparing the gold nanomaterial having characteristic absorption in the near infrared II region according to claim 1, characterized in that: In step (1), the chloroauric acid and MPA are stirred and reacted in an ice bath for 1-2 hours; in step (2), CA is added and stirred and reacted for 0.5-1 hour; in step (3), sodium hydroxide is added to adjust the pH to 12 and the stirring reaction is continued for 10-30 minutes; in step (4), sodium borohydride, a reducing agent, is added and stirred and reacted for 19-24 hours. In steps (1) to (4), the reaction temperature is 0-4°C and the rotation speed is 750-1000 rpm.

4. The method for preparing the gold nanomaterial having characteristic absorption in the near infrared II region according to claim 1, characterized in that: In step (5), the ultrafiltration purification at low temperature is to remove the unreacted substrate and concentrate the solution after the stirring reaction is completed by centrifugation using an ultrafiltration tube; wherein the temperature during the purification process is 0-4°C, the rotation speed is 3750-4000rpm, the pore size of the ultrafiltration tube membrane is 3-10kDa, the ultrafiltration centrifugation time is 12-15min, the number of ultrafiltration washes is 6-7, the solvent added for washing is deionized water, and ultrafiltration is concentrated after the washing is completed; the pH of the sample obtained after the ultrafiltration purification process is completed is 6.5-7.

4.

5. The gold nanomaterial having characteristic absorption in the near-infrared II region obtained by the preparation method according to any one of claims 1 to 4.

6. Use of the gold nanomaterial having characteristic absorption in the near infrared II region as claimed in claim 5 in the preparation of a photosensitizer-photothermal agent, characterized in that: The gold nanomaterial with characteristic absorption in the near-infrared II region generates reactive oxygen species (ROS) and photothermal effect under the irradiation of a laser with a specific wavelength.

7. The use of the gold nanomaterial having characteristic absorption in the near infrared II region in the preparation of a photosensitizer-photothermal agent according to claim 6, characterized in that: The method of using the gold nanomaterial having characteristic absorption in the near-infrared II region to generate ROS under laser irradiation of a specific wavelength comprises the following steps: The prepared gold nanomaterials with characteristic absorption in the near-infrared II region were mixed with the capture agent, irradiated with laser, and the generation of ROS was detected by electron spin resonance spectrometer ESR; The scavengers are hydroxyl radical (·OH) scavengers: 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and singlet oxygen ( 1 O2) capture agent: 2,2,6,6-tetramethylpiperidine (TEMP), laser wavelength is 1064nm, and irradiation time is 20min.

8. The use of the gold nanomaterial having characteristic absorption in the near-infrared II region in the preparation of a photosensitizer-photothermal agent according to claim 6, characterized in that: The method for using the gold nanomaterial having characteristic absorption in the near-infrared II region to produce a photothermal effect under irradiation of a laser of a specific wavelength comprises the following steps: The prepared concentrated sample of gold nanomaterials with characteristic absorption in the near-infrared II region was diluted with deionized water, irradiated with laser light, and the temperature change of the sample with irradiation time was monitored using a thermal camera; The concentrated sample of gold nanomaterial with characteristic absorption in the near-infrared II region has a dilution concentration of 10-100 μM, a laser wavelength of 1064 nm, and a laser power of 0.25-1.00 W / cm 2 , the illumination time was 5 min, and the temperature was recorded every 10 s.

9. The use of the gold nanomaterial having characteristic absorption in the near-infrared II region in the preparation of a photosensitizer-photothermal agent according to claim 6, characterized in that: The method for improving the photothermal stability of the gold nanomaterial having characteristic absorption in the near-infrared II region under irradiation of a laser of a specific wavelength comprises the following steps: The concentrated sample of the gold nanomaterial having characteristic absorption in the near-infrared II region is diluted, irradiated with laser light, and the temperature change of the sample over the irradiation time is monitored using a thermal camera; after stopping the laser irradiation, the temperature change of the sample is continuously monitored using the thermal camera while the sample is cooled; this step is repeated three times; The gold nanomaterial concentrated sample with characteristic absorption in the near-infrared II region has a dilution concentration of 100 μM, a laser wavelength of 1064 nm, and a laser power of 0.75 W / cm 2 , the illumination time was 4 min, the cooling time was 16 min, and the temperature was recorded every 10 s.

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