A kind of polydopamine-polyrotaxane nanoparticles chelating calcium and its preparation method and application

Abstract

This invention discloses a calcium-chelating polydopamine-polyrotaxane nanoparticle, its preparation method, and its application, comprising the following steps: (1) aging dopamine hydrochloride in an alkaline solution, centrifuging to obtain polydopamine nanoparticles; dispersing cyclodextrin and bis-thiol-terminated polyethylene glycol in water, stirring at 0-5°C to prepare polyrotaxane; (2) reacting the obtained polydopamine nanoparticles with polyrotaxane in an alkaline solution to obtain polydopamine-polyrotaxane nanoparticles; (3) stirring the polydopamine-polyrotaxane nanoparticles with calcium salt in an alkaline solution to obtain calcium-chelating polydopamine-polyrotaxane nanoparticles. The nanoparticles prepared by the above method have long-term stable photothermal conversion capabilities and high calcium loading capacity, and can be used for tumor treatment through photothermal effect synergistic controllable calcium overloading.

Description

Technical Field

[0001] This invention relates to the fields of material preparation and tumor treatment, specifically to a calcium-chelated polydopamine-polyrotaxane nanoparticle, its preparation method, and its application. Background Technology

[0002] According to the 2023 Cancer Report, with the continuous advancement of medical technology, the overall cancer mortality rate has decreased by 33%. However, the diagnosis and mortality rates of colorectal cancer remain high. Currently, the main clinical treatments for colorectal cancer include surgical resection, radiotherapy, chemotherapy, and immunotherapy. However, these therapies have limitations such as numerous contraindications and severe adverse reactions. Therefore, research into non-invasive, precise therapies with minimal side effects is of great significance, such as phototherapy, sound therapy, magnetotherapy, and electrotherapy. Due to the advantages of near-infrared light, such as its deep tissue penetration and strong remote controllability, nanocarrier-mediated tumor phototherapy has made great progress, especially the representative photothermal therapy and photodynamic therapy. Photothermal therapy is a non-invasive therapy that utilizes photothermal conversion agents exposed to external light sources such as near-infrared light to convert light energy into heat energy to kill tumor cells. It has advantages such as minimal side effects, high specificity, and repeatable treatment.

[0003] Photothermal conversion agents are the core of photothermal therapy and can be broadly classified into four categories: noble metal materials (such as gold and silver nanoparticles), inorganic materials (such as carbon nanotubes and graphene), organic polymer materials (such as polypyrrole and polyaniline), and organic small molecule materials (such as cyanine dyes). Polydopamine, as one of the most attractive biomimetic photothermal agents, possesses high photothermal conversion efficiency, good biocompatibility, biodegradability, photothermal stability, and ease of chemical modification. Furthermore, the numerous functional groups on its surface, especially amino and catechol groups, provide binding sites for metal ions (iron, calcium, and copper ions).

[0004] Single-modality tumor treatments are rarely able to achieve complete tumor ablation, and treatment strategies have gradually shifted towards multimodal combination therapies. As a fundamental element for cell survival, Ca... 2+ Mitochondria regulate physiological activities including cell proliferation, invasion, and apoptosis. Mitochondria are regulators of intracellular calcium... 2+ The key part of steady state. Therefore, Ca 2+ Overload therapy holds promise as an effective strategy for clinical oncology treatment. Transient receptor channels (TRPs) are a type of non-selective Ca2+ receptor antagonist. 2+ Permeable cation channels have been extensively studied as tumor targets. Among them, the TRPV1 thermosensitive cation channel modulates Ca2+ through thermoregulation. 2+ One of the TRP channels that promotes apoptosis, its thermal activation threshold is approximately 43°C, and it can be activated by conventional photothermal therapy. However, due to insufficient calcium ions at the tumor site, Ca...2+ The low efficiency of calcium ion entry into tumors leads to unsatisfactory treatment outcomes. Therefore, it is necessary to increase calcium ions through external means to overcome the limitation of insufficient concentration. Inorganic calcium salts such as calcium carbonate, calcium peroxide, and calcium phosphate are commonly used and ideal calcium ion donors. However, the large-scale introduction of exogenous calcium inevitably leads to a decrease in plasma calcium levels. 2+ Rapidly increasing calcium levels, causing a sharp drop in blood pH, inflammatory reactions in the body, and the formation of inorganic calcium salt stones, makes it unsuitable for widespread application. Therefore, achieving controllable chelated calcium overload is particularly important. Summary of the Invention

[0005] This invention provides calcium-chelating polydopamine-polyrotaxane nanoparticles, their preparation method, and applications. Uniform polydopamine nanoparticles with photothermal effects are prepared via solution oxidation and differential centrifugation. A precisely targeted polyrotaxane, prepared from 2-hydroxypropyl-β-cyclodextrin and bi-thiol-terminated polyethylene glycol, is capped onto the polydopamine via Michael addition, effectively preventing the decyclization of 2-hydroxypropyl-β-cyclodextrin during use. These nanoparticles possess photothermal properties and can utilize the calcium-chelating function of the cyclodextrin-polyrotaxane surface to chelate calcium, thereby obtaining nanoparticles with high calcium loading capacity, which can be used for photothermally controlled calcium overload tumor therapy.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a method for preparing calcium-chelated polydopamine-polyrotaxane nanoparticles, comprising the following steps:

[0008] (1) Dopamine hydrochloride was aged in an alkaline solution and centrifuged to obtain polydopamine nanoparticles; cyclodextrin and double-terminated mercapto polyethylene glycol were dispersed in water and stirred at 0-5℃ to prepare polyrotaxane;

[0009] (2) The polydopamine nanoparticles prepared in step (1) are reacted with polyrotaxane in an alkaline solution to obtain polydopamine-polyrotaxane nanoparticles;

[0010] (3) The polydopamine-polyrotaxane nanoparticles prepared in step (2) are stirred with calcium salt in an alkaline solution, and after dialysis with deionized water and freeze-drying, calcium-chelated polydopamine-polyrotaxane nanoparticles are obtained.

[0011] Further, in step (1), the pH of the alkaline solution is not lower than 8.0, and the alkaline reagent in the alkaline solution is one or more of sodium hydroxide, ammonia, and Tris-HCl. More preferably, the alkaline solution is an aqueous solution of sodium hydroxide.

[0012] In some preferred embodiments, dopamine hydrochloride is dissolved in 90 mL of water, and 500-1000 μL of 1 M sodium hydroxide solution is added for aging.

[0013] Further, in step (1), the aging temperature is 40-70℃, such as 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, etc., including but not limited to the temperatures listed above, and the aging time is 4-8h, such as 4h, 5h, 6h, 7h, 8h, etc., including but not limited to the times listed above.

[0014] Further, in step (1), the centrifugation step is specifically as follows: first, centrifuge at 3000-5000 rpm, take the supernatant and centrifuge at 12000-16000 rpm, collect the precipitate; freeze-dry the collected precipitate to obtain the polydopamine nanoparticles.

[0015] Further, in step (1), the molecular weight of the double-terminated thiol polyethylene glycol is 5000-20000, more preferably around 10000, and the molecular weight distribution is less than 1.05; the general structural formula of the double-terminated thiol polyethylene glycol is as follows:

[0016] Where n is an integer between 111 and 444.

[0017] Further, in step (1), the cyclodextrin is selected from one or more of α-cyclodextrin, β-cyclodextrin, 2-hydroxypropyl-α-cyclodextrin, and 2-hydroxypropyl-β-cyclodextrin, more preferably 2-hydroxypropyl-β-cyclodextrin.

[0018] Further, in step (1), the molar ratio of the cyclodextrin to the bi-terminated mercapto polyethylene glycol is 40-50:1.

[0019] Furthermore, in step (1), the stirring time is 24-48 hours.

[0020] Further, in step (2), the mass ratio of the polydopamine nanoparticles to polyrotaxane is 5-10 mg: 0.3-1 g.

[0021] Further, in step (2), the pH of the alkaline solution is not lower than 8.0; in some preferred embodiments, polydopamine is added to water, then 1M sodium hydroxide solution is added to adjust the pH to 8-9, and then polyrotaxane is added to react.

[0022] Furthermore, in step (2), the reaction temperature is 10-40℃ and the reaction time is 12-24h.

[0023] Furthermore, in step (3), the pH of the alkaline solution is not lower than 8.0; the calcium salt is one or more of calcium chloride, calcium acetate, and calcium gluconate.

[0024] In some preferred embodiments, polydopamine-polyrotaxane nanoparticles are dispersed in an alkaline solution, and then a calcium-containing aqueous solution prepared by dissolving calcium salt in Tris-HCl buffer solution is added and stirred. The alkaline solution is preferably a Tris-HCl buffer solution with a pH of 8-10, and the concentration of the calcium-containing aqueous solution is 0.2-1M, more preferably 0.5M.

[0025] Furthermore, in step (3), the stirring temperature is 25-50°C, more preferably 37°C, and the stirring time is 24-72h, for example 48h.

[0026] The mechanism by which this invention synthesizes calcium-chelating polydopamine-polyrotaxane nanoparticles via the above-mentioned solution oxidation method and Michael addition reaction is as follows: Dopamine monomers are oxidized under alkaline and oxygen conditions and spontaneously self-polymerize into cross-linked polymers. By controlling the reaction conditions, polydopamines of different morphologies and sizes can be prepared. 2-Hydroxypropyl-β-cyclodextrin (Hy-β-CD) is a common derivative of β-cyclodextrin. Each 2-hydroxypropyl-β-cyclodextrin molecule has seven 2-hydroxypropyl groups randomly substituted on the cyclodextrin pyranose units. Due to the presence of substituents, the hydrogen bonds between Hy-β-CD molecules are weakened. In aqueous solution, 2-hydroxypropyl-β-cyclodextrin and polyethylene glycol macromonomers can be mixed and assembled into quasi-polyrotaxanes at any concentration and in any proportion without producing any crystals. Within the lumen of the Hy-β-CD chain strung on the PEG chain, in addition to the PEG segments, there are gaps. Therefore, the methyl groups on the 2-hydroxypropyl groups of other Hy-β-CDs can still be inserted into these gaps from the large and small edges. The Hy-β-CDs strung on the polyethylene glycol macromonomer can cause the PEG chain to extend, thus allowing for significant overall deformation. This provides the possibility of simultaneously end-capping both ends of a quasi-polyrotaxane onto a polydopamine nanoparticle.

[0027] The second aspect of the present invention provides polydopamine-polyrotaxane nanoparticles with chelated calcium prepared by the preparation method described in the first aspect.

[0028] Furthermore, the calcium loading in the chelated calcium polydopamine-polyrotaxane nanoparticles increases with the increase of polyrotaxane content in the polydopamine-polyrotaxane.

[0029] The third aspect of the present invention provides the use of the calcium-chelating polydopamine-polyrotaxane nanoparticles described in the second aspect in the preparation of photothermal therapeutic drugs and / or ion interference therapeutic drugs.

[0030] Combining polydopamine with polyrotaxane can, on the one hand, make polyrotaxane nanoparticles visible and endow them with photothermal effects; on the other hand, it can also greatly enhance the calcium chelating ability of polydopamine, exhibiting good biocompatibility. The two complement each other. Simultaneously, the photothermal effect can also open the TRPV1 thermosensitive cation channel, promoting extracellular calcium absorption. 2+ Intravenous influx enhances the therapeutic effect of calcium overload.

[0031] In some preferred embodiments, the photothermal therapeutic performance of chelated calcium polydopamine-polyrotaxane nanoparticles is evaluated by in vitro photothermal performance testing, specifically as follows: Different concentrations of chelated calcium-polydopamine-polyrotaxane nanoparticles are prepared and irradiated with a laser. The temperature change of the solution is recorded every half minute, and its optical properties as a function of temperature are observed. The laser wavelength is 808 nm, and the power is 1.0 W / cm². 2 The irradiation time is 10 minutes.

[0032] In some preferred embodiments, the calcium loading of the calcium-chelated polydopamine-polyrotaxane nanoparticles is determined by inductively coupled plasma atomic emission spectrometry.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. This invention first prepares polydopamine nanoparticles via solution oxidation, and then covalently links cyclodextrin-based polyrotaxane to the polydopamine surface via Michael addition reaction to obtain polydopamine-polyrotaxane nanoparticles with calcium chelation function. Then, the abundant ether bonds in the polydopamine-polyrotaxane nanoparticles are used to chelate calcium, thus providing a simple and efficient method for preparing polydopamine-polyrotaxane nanoparticles with high calcium loading. This preparation method avoids the difficulties of end-capping quasi-polyrotaxane, preparing cyclic polyrotaxane, and chelating calcium in the two-step synthesis methods of existing technologies. Furthermore, the polydopamine nanoparticles prepared by this method are uniform in size and possess excellent photothermal properties. End-capping both ends of the quasi-polyrotaxane on a polydopamine surface makes it difficult for cyclodextrin to de-ring during use, resulting in long-term stable photothermal conversion performance. It also exhibits high calcium loading and good biocompatibility, providing a novel calcium chelating material for the current field of ion interference therapy.

[0035] 2. The polydopamine-polyrotaxane nanoparticles with chelated calcium prepared by this invention exhibit excellent photothermal conversion performance and long-term stability. These nanoparticles can rapidly heat up under near-infrared light irradiation. For example, when a PBS dispersion containing 0.2 mg / mL nanoparticles is irradiated with 808 nm near-infrared light, the temperature of the dispersion rises to 61.5 °C after 10 min of irradiation. Cyclic test results show that the nanoparticles have good photothermal conversion stability and can be reused. In addition, the calcium loading rate of the above-mentioned polydopamine-polyrotaxane nanoparticles with chelated calcium increases with the increase of polyrotaxane content in the nanoparticles, and nanoparticles with a calcium loading rate of 6.52% can be obtained. Attached Figure Description

[0036] Figure 1 A schematic diagram of the synthesis routes for polydopamine-polyrotaxane nanoparticles (PDA-PR) and chelated calcium-polydopamine-polyrotaxane nanoparticles (Ca@PDA-PR);

[0037] Figure 2 Transmission electron microscope image of polydopamine;

[0038] Figure 3 The image shows the dynamic light scattering characterization of polydopamine nanoparticles.

[0039] Figure 4 Fourier transform infrared spectra of double-terminated mercapto-based polyethylene glycol, polydopamine, and polydopamine-polyrotaxane nanoparticles;

[0040] Figure 5 The 1H NMR spectra of quasi-polyrotaxane and polydopamine-polyrotaxane nanoparticles;

[0041] Figure 6 X-ray diffraction patterns of β-cyclopaste-precise polyrotaxane, 2-hydroxypropyl-β-cyclopaste-precise polyrotaxane, and polydopamine-polyrotaxane nanoparticles;

[0042] Figure 7 Transmission electron microscope image of chelated calcium-polydopamine-polyrotaxane nanoparticles;

[0043] Figure 8 The ultraviolet absorption spectra of dopamine, polydopamine, polydopamine-polyrotaxane, and chelated calcium-polydopamine-polyrotaxane are shown.

[0044] Figure 9 The graph shows the heating effect of chelated calcium-polydopamine-polyrotaxane nanoparticles.

[0045] Figure 10 The graph shows the temperature cycling test results of chelated calcium-polydopamine-polyrotaxane nanoparticles. Detailed Implementation

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. "Comprising" or "containing" as used herein means that it may include or contain other components in addition to the stated components. "Comprising" or "containing" as used herein may also be replaced with the closed form "is" or "consisting of".

[0047] The present invention will be further described below with reference to specific embodiments and accompanying drawings, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0048] Example

[0049] This embodiment relates to a polydopamine-polyrotaxane nanoparticle with calcium chelation function and the preparation of chelated calcium-polydopamine-polyrotaxane nanoparticles. Polydopamine nanoparticles are prepared by solution oxidation of dopamine hydrochloride. Polydopamine-polyrotaxane nanoparticles are prepared by Michael addition reaction of 2-hydroxypropyl-β-cyclopaste polyrotaxane with polydopamine. Then, the polydopamine-polyrotaxane nanoparticles are subjected to surface calcium coordination treatment to obtain chelated calcium-polydopamine-polyrotaxane nanoparticles. A schematic diagram of the synthesis route is shown below. Figure 1 As shown, the specific process is as follows:

[0050] (1) Synthesis of polydopamine-polyrotaxane nanoparticles:

[0051] Preparation of polydopamine nanoparticles: 90 mL of deionized water was added to a round-bottom flask and heated to 50 °C; then 180 mg of dopamine hydrochloride was added, followed by 760 μL of 1 M sodium hydroxide aqueous solution, and the mixture was aged for 5 hours; after centrifugation at 4000 rpm for 5 minutes, the supernatant was collected and centrifuged again at 14000 rpm, and the precipitate was freeze-dried to obtain polydopamine nanoparticles for later use.

[0052] Preparation of 2-hydroxypropyl-β-cyclodextrin precise polyrotaxane: 3.50 g of 2-hydroxypropyl-β-cyclodextrin and 20 mL of deionized water were added to a round-bottom flask and sonicated for at least 10 minutes; then 0.50 g of bis-thiol-terminated polyethylene glycol (molecular weight 10000) was added, the flask was purged with argon gas and sealed, and the solution was sonicated vigorously for at least 10 minutes until it became homogeneous and transparent. After stirring in an ice bath for 48 hours, 2-hydroxypropyl-β-cyclodextrin precise polyrotaxane was obtained and set aside for later use without further processing.

[0053] Preparation of polydopamine-polyrotaxane nanoparticles: 10 mg of the prepared polydopamine nanoparticles and 5 mL of deionized water were added to a single-necked flask. The pH was then adjusted to 8.5 with 1 M sodium hydroxide aqueous solution, and the mixture was sonicated for 10 minutes. 3 mL of the 2-hydroxypropyl-β-cyclopaste-precise polyrotaxane prepared above was added to the single-necked flask, and the reaction was allowed to proceed for 12 hours. After the reaction, the mixture was dialyzed against deionized water for 7 days and then lyophilized for later use to obtain polydopamine-polyrotaxane nanoparticles.

[0054] The polydopamine nanoparticles, quasi-polyrotaxane, or polydopamine-polyrotaxane nanoparticles prepared in this embodiment were characterized by ultraviolet-visible absorption, transmission electron microscopy, dynamic light scattering, 1H NMR, X-ray diffraction, or infrared spectroscopy. The characterization results are shown below:

[0055] Figure 2 The image shows a transmission electron microscope image of polydopamine nanoparticles. As can be seen from the image, the polydopamine prepared in this embodiment is spherical and has a uniform particle size.

[0056] Figure 3 The figure shows the dynamic light scattering characterization of polydopamine nanoparticles. As can be seen from the figure, the particle size of the nanoparticles is mainly concentrated around 150 nm, and its polydispersity is 0.277.

[0057] Figure 4 Fourier transform infrared spectra of polyethylene glycol with thiol-terminated ends, polydopamine, and polydopamine-polyrotaxane nanoparticles, at 3400 cm⁻¹. -1 and 1600cm -1 The absorption peaks at 2688 cm⁻¹ represent the stretching vibrations of catechol and indole or dihydroindole, respectively, indicating the formation of polydopamine; -1 The absorption peak of -SH in the quasi-polyrotaxane (Looped-PPR in the figure) appears at 2688 cm⁻¹, while the absorption peak of -SH in the polydopamine-polyrotaxane nanoparticles (Looped-PR in the figure) is at 2688 cm⁻¹. -1 The disappearance of the -SH absorption peak indicates that polydopamine and 2-hydroxypropyl-β-cyclopaste precise polyrotaxane are covalently bonded. The above characterization data confirm that 2-hydroxypropyl-β-cyclopaste precise polyrotaxane is successfully capped by polydopamine.

[0058] Figure 5 The figures show the 1H NMR spectra of quasi-polyrotaxane and polydopamine-polyrotaxane nanoparticles. As can be seen from the figure, the integration of the methylene hydrogen at C1 of the cyclodextrin and the repeating unit (-CH2-CH2-) of polyethylene glycol can be used to calculate that there are approximately 12 2-hydroxypropyl-β-cyclodextrins on the quasi-polyrotaxane, and 6 2-hydroxypropyl-β-cyclodextrins in each polyethylene glycol (molecular weight 10000) strand on the polydopamine-polyrotaxane.

[0059] In addition, this invention also uses β-cyclodextrin to replace the above-mentioned 2-hydroxypropyl-β-cyclodextrin to prepare β-cyclodextrin-precise polyrotaxane. The X-ray diffraction patterns of the prepared β-cyclodextrin-precise polyrotaxane, 2-hydroxypropyl-β-cyclodextrin-precise polyrotaxane, and polydopamine-polyrotaxane nanoparticles (prepared using 2-hydroxypropyl-β-cyclodextrin) are shown in the figure. Figure 6 As shown in the figure, β-cyclodextrin-based precise polyrotaxanes possess crystalline regions, while 2-hydroxypropyl-β-cyclodextrin-based precise polyrotaxanes and polydopamine-based polyrotaxane nanoparticles lack crystalline regions due to the inhibition of hydrogen bonds between cyclodextrins by the hydroxypropyl groups. The Hy-β-CD chained onto the polyethylene glycol (PEG) macromonomer allows for PEG chain extension, resulting in significant overall deformation and providing the possibility of simultaneously capping both ends of the quasi-polyrotaxane onto a single polydopamine nanoparticle.

[0060] (2) Synthesis of chelated calcium-polydopamine-polyrotaxane nanoparticles

[0061] The polydopamine-polyrotaxane nanoparticles prepared in this embodiment were subjected to surface calcium coordination treatment to obtain chelated calcium-polydopamine-polyrotaxane nanoparticles. The specific operation is as follows:

[0062] In a round-bottom flask, 50 mg of lyophilized polydopamine-polyrotaxane nanoparticles and 5 mL of Tris-HCl buffer were added sequentially, and the mixture was sonicated for at least 10 minutes to ensure uniform dispersion of the nanoparticles. Then, 5 mL of 0.5 M calcium chloride solution (obtained by dispersing calcium chloride in Tris-HCl buffer at pH 8.5) was added, and the mixture was sonicated for 5 minutes. The mixture was then slowly stirred in a 37°C water bath for three days. After the reaction was complete, the nanoparticles were dialyzed in aqueous solution for three days using a dialysis bag with a molecular weight cutoff of 7000. The resulting lyophilized nanoparticles were then obtained.

[0063] The chelated calcium-polydopamine-polyrotaxane nanoparticles prepared in this embodiment were characterized by transmission electron microscopy and ultraviolet-visible absorption microscopy. The characterization results are shown below:

[0064] Figure 7 The image shows a transmission electron microscope image of chelated calcium-polydopamine-polyrotaxane nanoparticles. As can be seen from the image, the chelated calcium-polydopamine-polyrotaxane nanoparticles prepared in this embodiment are spherical and have a uniform particle size.

[0065] Figure 8 The figures show the ultraviolet absorption spectra of dopamine (DA), polydopamine (PDA), polydopamine-polyrotaxane (Looped-PR), and chelated calcium-polydopamine-polyrotaxane (Looped-PR@Ca). As can be seen from the figures, the polydopamine, polydopamine-polyrotaxane, and chelated calcium-polydopamine-polyrotaxane prepared in this example all have different degrees of absorption of light within the wavelength range of 800 nm.

[0066] Performance testing

[0067] 1. Photothermal performance testing of chelated calcium-polydopamine-polyrotaxane nanoparticles

[0068] (1) Photothermal conversion effect test

[0069] To verify the photothermal conversion effect of chelated calcium-polydopamine-polyrotaxane nanoparticles, dispersions of chelated calcium-polydopamine-polyrotaxane nanoparticles at different concentrations in PBS buffer were prepared in vials: 0 mg / mL, 0.05 mg / mL, 0.10 mg / mL, 0.15 mg / mL, and 0.20 mg / mL. The nanoparticles were sonicated for at least 10 minutes to ensure uniform dispersion. 1 mL of each dispersion was then added to a cuvette, and the nanoparticles in the cuvette were irradiated with an 808 nm near-infrared laser at a power of 1.0 W cm⁻¹. -2 The photothermal conversion of nanoparticles was recorded by an infrared thermal imaging camera under different light exposure times, and temperature versus time curves were plotted.

[0070] Test results are as follows Figure 9 As shown, using PBS buffer as a reference, nanoparticle dispersions of different concentrations rapidly heated after the light source was turned on, exhibiting a clear concentration dependence. With increasing concentration, water could be heated to 47.5℃, 51.7℃, 58.2℃, and 61.5℃ within 10 minutes, respectively, and the heating rate plateaued around 8 minutes, demonstrating excellent photothermal conversion performance.

[0071] (2) Photothermal conversion stability test

[0072] To verify the photostability and reusability of chelated calcium-polydopamine-polyrotaxane nanoparticles, a dispersion of chelated calcium-polydopamine-polyrotaxane nanoparticles in PBS buffer was prepared in vials at a concentration of 0.10 mg / mL. The nanoparticles were sonicated for at least 10 minutes to ensure uniform dispersion. 1 mL of this dispersion was then added to cuvettes, and the nanoparticles in the cuvettes were irradiated with an 808 nm near-infrared laser at a power of 1.0 W cm⁻¹. -2 The photothermal conversion of nanoparticles was recorded using an infrared thermal imaging camera under different light exposure times, and temperature versus time curves were plotted. After 10 minutes of light exposure, the temperature rapidly increased to approximately 50.7°C; subsequently, the light source was turned off, and the water temperature decreased, returning to near its initial temperature after 10 minutes. This process was repeated four times.

[0073] The results of the loop test are as follows Figure 10As shown, the heating effect of chelated calcium-polydopamine-polyrotaxane nanoparticles did not decrease significantly in 4 cycles, and the water temperature could be heated to around 50°C in each cycle. This result indicates that the nanoparticles synthesized in this invention have good photostability and reusability.

[0074] 2. Calcium loading test

[0075] To verify the calcium loading capacity of chelated calcium-polydopamine-polyrotaxane nanoparticles, polydopamine-polyrotaxane nanoparticles with different polyrotaxane addition amounts were prepared during the preparation process of polydopamine-polyrotaxane nanoparticles. The specific operations are as follows:

[0076] Preparation of three types of polydopamine-polyrotaxane nanoparticles: 10 mg of the prepared polydopamine nanoparticles and 5 mL of deionized water were added to three single-necked flasks, respectively. The pH was then adjusted to 8.5 with 1 M sodium hydroxide aqueous solution, and the mixture was sonicated for 10 minutes. 3 mL, 4 mL, and 5 mL of the 2-hydroxypropyl-β-cyclohexane precisely prepared polyrotaxane were added to the three single-necked flasks, respectively, and reacted for 12 hours. After the reaction, the mixture was dialyzed against deionized water for 7 days and then lyophilized for later use, yielding three different types of polydopamine-polyrotaxane nanoparticles.

[0077] Preparation of three types of chelated calcium-polydopamine-polyrotaxane nanoparticles: The preparation process is the same as in Example 1.

[0078] Then, 5 mL dispersions of three different chelated calcium-polydopamine-polyrotaxane nanoparticles in PBS buffer were prepared in separate vials, with a concentration of 0.25 mg / mL. The dispersions were sonicated for at least 10 minutes to ensure uniform dispersion. 2 mL of each dispersion was transferred to a beaker, followed by 2 mL of freshly prepared aqua regia. The beakers were heated in a 250°C heating mantle for 10 minutes, stopping heating when 0.5 mL of solution remained. The filter was then used to prepare the test solution. The calcium loading efficiency of the different polydopamine-polyrotaxane nanoparticles was then determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). Each sample was measured three times, and the average value was taken.

[0079] The test results are shown in Table 1 below:

[0080] Table 1

[0081] sample PDA dosage / mg <![CDATA[V PPR / mL]]> Calcium loading efficiency / % 1 10 3 4.74 2 10 4 6.06 3 10 5 6.52

[0082] As shown in Table 1, the calcium loading efficiency of the chelated calcium-polydopamine-polyrotaxane nanoparticles prepared in this invention increases with the increase of polyrotaxane content; when 5 mL of polyrotaxane solution is added to prepare polydopamine-polyrotaxane nanoparticles, the calcium loading efficiency of the prepared nanoparticles can reach 6.52%.

[0083] The embodiments described above are merely preferred examples to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing calcium-chelated polydopamine-polyrotaxane nanoparticles, characterized in that, Includes the following steps: (1) Dopamine hydrochloride was aged in an alkaline solution and centrifuged to obtain polydopamine nanoparticles; cyclodextrin and bi-thiol-terminated polyethylene glycol were dispersed in water and stirred at 0-5℃ to prepare polyrotaxane; (2) The polydopamine nanoparticles prepared in step (1) are reacted with polyrotaxane in an alkaline solution to obtain polydopamine-polyrotaxane nanoparticles. (3) The polydopamine-polyrotaxane nanoparticles prepared in step (2) are stirred with calcium salt in an alkaline solution, and after dialysis with deionized water and freeze-drying, calcium-chelated polydopamine-polyrotaxane nanoparticles are obtained.

2. The preparation method according to claim 1, characterized in that, In step (1), the pH of the alkaline solution is not lower than 8.0, and the alkaline reagent in the alkaline solution is one or more of sodium hydroxide, ammonia and Tris-HCl; The aging temperature is 40-70℃, and the aging time is 4-8 hours; The centrifugation steps are as follows: first, centrifuge at 3000-5000 rpm, take the supernatant and centrifuge at 12000-16000 rpm, and collect the precipitate.

3. The preparation method according to claim 1, characterized in that, In step (1), the molecular weight of the double-terminated mercapto polyethylene glycol is 5000-20000, and the molecular weight distribution is less than 1.05; The cyclodextrin is selected from one or more of α-cyclodextrin, β-cyclodextrin, 2-hydroxypropyl-α-cyclodextrin, and 2-hydroxypropyl-β-cyclodextrin.

4. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of cyclodextrin to bis-thiol polyethylene glycol is 40-50:1; the stirring time is 24-48h.

5. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the polydopamine nanoparticles to polyrotaxane is 5-10 mg: 0.3-1 g.

6. The preparation method according to claim 1, characterized in that, In step (2), the pH of the alkaline solution is not lower than 8.0; the reaction temperature is 10-40℃ and the reaction time is 12-24h.

7. The preparation method according to claim 1, characterized in that, In step (3), the pH of the alkaline solution is not lower than 8.0; the calcium salt is one or more of calcium chloride, calcium acetate, and calcium gluconate.

8. The preparation method according to claim 1, characterized in that, In step (3), the stirring temperature is 25-50℃ and the stirring time is 24-72h.

9. A polydopamine-polyrotaxane nanoparticle with chelated calcium prepared by the preparation method according to any one of claims 1-8.

10. The use of the calcium-chelating polydopamine-polyrotaxane nanoparticles of claim 9 in the preparation of photothermal therapeutic drugs and / or ion interference therapeutic drugs.

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