Drug-loaded composite nanoparticle as well as preparation method and application thereof

Abstract

The invention relates to the technical field of materials for preventing and treating local infection, in particular to drug-loaded composite nanoparticles as well as a preparation method and application thereof. The drug-loaded composite nanoparticles provided by the invention comprise hollow polydopamine grafted with vancomycin and lipoic acid-quaternary ammonium salt ionic liquid loaded into a cavity of the hollow polydopamine. In the invention, the HPDA nanoparticles have a hollow structure, and the structure provides sufficient space for loading of drug molecules. The lipoic acid-quaternary ammonium salt ionic liquid can generate heat energy under the microwave heat effect, and bacteria are effectively killed. Besides, under microwave stimulation, the lipoic acid-quaternary ammonium salt ionic liquid not only can enhance the sterilization effect, but also can reduce inflammatory response caused by bacterial infection through the synergistic effect of microwave heat effect and chemical sterilization.

Description

Technical Field

[0001] This invention relates to the field of materials for the prevention and treatment of local infections, and in particular to a drug-loaded composite nanoparticle, its preparation method, and its application. Background Technology

[0002] Subcutaneous abscesses are localized purulent inflammations caused by bacterial infection, usually accompanied by symptoms such as pain and swelling. In severe cases, they can lead to tissue necrosis and functional impairment. This disease not only seriously affects the patient's health but can also cause complications such as pneumonia, tuberculosis, sepsis, gonorrhea, and foodborne illnesses. Current treatment methods mainly rely on antibiotics, but due to the increasing prevalence of bacterial resistance, the effectiveness of antibiotics is constantly decreasing, and systemic administration often fails to ensure that the drug effectively concentrates at the site of infection, resulting in poor treatment outcomes.

[0003] To overcome this problem, local drug delivery systems (LDDS) have gradually become a research focus. Local drug delivery can directly deliver drugs to the site of infection, avoiding the side effects and low drug concentrations associated with systemic administration. Microneedles (MNs), as a novel local drug delivery method, can penetrate the skin in a minimally invasive and painless manner, providing a high drug loading capacity and achieving precise drug delivery, and are widely used in the treatment of local infections such as subcutaneous abscesses. However, current microneedle technology still faces some challenges, such as insufficient penetration and limited therapeutic efficacy. Summary of the Invention

[0004] The purpose of this invention is to provide a drug-loaded composite nanoparticle, its preparation method, and its application. The drug-loaded composite nanoparticle and microneedles provided by this invention can not only solve the problem of drug resistance in traditional antibiotic treatment, but also improve the local treatment effect through precise drug delivery, and have good biocompatibility and anti-inflammatory effects.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a drug-loaded composite nanoparticle comprising hollow polydopamine, a lipoic acid-quaternary ammonium salt ionic liquid loaded into the hollow polydopamine cavity, and vancomycin grafted onto the surface of the hollow polydopamine.

[0006] Preferably, the mass ratio of lipoic acid to quaternary ammonium salt in the lipoic acid-quaternary ammonium salt ionic liquid is 0.5~1:1; the quaternary ammonium salt includes one or more of dodecyl dimethyl benzyl ammonium chloride, dicedyl dimethyl ammonium chloride, and trioctyl methyl ammonium chloride.

[0007] Preferably, the mass ratio of the hollow polydopamine grafted with vancomycin to the lipoic acid-quaternary ammonium salt ionic liquid is 1~5:16~20; the mass ratio of the hollow polydopamine to vancomycin is 2~6:4.

[0008] Preferably, the preparation of the lipoic acid-quaternary ammonium salt ionic liquid includes the following steps: mixing an anhydrous ethanol solution of lipoic acid and an anhydrous ethanol solution of quaternary ammonium salt and then evaporating the mixture to obtain the lipoic acid-quaternary ammonium salt ionic liquid.

[0009] This invention also provides a method for preparing the drug-loaded composite nanoparticles described in the above technical solution, comprising the following steps: (1) Dissolve silica nanoparticles and dopamine, and polymerize and coat the resulting solution with dopamine to obtain silica with a polydopamine shell on the surface; (2) After mixing the aqueous dispersion of silica with a polydopamine shell on the surface and the hydrofluoric acid solution, the mixture is etched to obtain hollow polydopamine; (3) Vancomycin and hollow polydopamine were mixed and grafted to obtain hollow dopamine grafted with vancomycin. (4) The lipoic acid-quaternary ammonium salt ionic liquid and vancomycin-grafted hollow dopamine are mixed, and the resulting mixture is subjected to ultrasonic treatment and filtration in sequence to obtain the drug-loaded composite nanoparticles.

[0010] Preferably, the concentration of the hydrofluoric acid solution is 20~22.5 mol / L; the etching treatment is performed at room temperature for 1~2 hours.

[0011] Preferably, the grafting reaction is carried out at room temperature for 24-48 hours. The ultrasonic treatment has a power of 40-50W and a duration of 10-15 minutes.

[0012] The present invention also provides a drug-loaded microneedle, comprising drug-loaded composite nanoparticles and a microneedle; the drug-loaded composite nanoparticles are the drug-loaded composite nanoparticles described in the above technical solution or the drug-loaded composite nanoparticles prepared by the above preparation method.

[0013] This invention also provides a method for preparing the drug-loaded microneedles described above, comprising the following steps: After injecting a dispersion of drug-loaded composite nanoparticles into a microneedle template, the drug-loaded composite nanoparticles are coated onto the surface of the microneedle using vacuum adsorption and then dried to obtain the drug-loaded microneedle.

[0014] This invention also provides the application of the drug-loaded composite nanoparticles described in the above technical solutions or the drug-loaded composite nanoparticles prepared by the above preparation methods, and the drug-loaded microneedles described in the above technical solutions or the drug-loaded microneedles prepared by the above preparation methods in the preparation of products for the prevention and / or treatment of subcutaneous abscesses.

[0015] In this invention, HPDA nanoparticles possess a hollow internal structure, providing ample space for drug molecule loading. The lipoic acid-quaternary ammonium salt ionic liquid generates heat energy under microwave thermal effects, effectively killing bacteria. Furthermore, lipoic acid (LA), as an antioxidant, can scavenge free radicals in the body and exert anti-inflammatory effects by regulating the immune system. Additionally, under microwave stimulation, the lipoic acid-quaternary ammonium salt ionic liquid, through the synergistic effect of microwave thermal effects and chemical sterilization, not only enhances the bactericidal effect but also reduces the inflammatory response caused by bacterial infection. Lipoic acid (LA) can further reduce local inflammation through its anti-inflammatory properties, helping to alleviate tissue damage and promote healing.

[0016] The drug-loaded microneedles of this invention, by uniformly coating the drug-loaded composite nanoparticles (ILs@HPDAs-Van) into a microneedle mold, utilize the minimally invasive nature and local drug delivery advantages of microneedles to precisely deliver drugs to the site of infection. The synergistic effect of microwave thermal effect and the antibacterial component quaternary ammonium salt in the ionic liquid, aided by the microneedle system, can significantly increase the drug concentration at the local infection site, and further enhance the therapeutic effect through microwave stimulation. Compared with traditional antibiotic treatment, the drug-loaded microneedles of this invention not only enhance the bactericidal effect through the synergistic effect of microwave thermal effect and chemical bactericidal action, but also avoid the problem of antibiotic resistance. The composite ionic liquid (ILs) combining quaternary ammonium salt (QAC) and lipoic acid (LA) optimizes the antibacterial and anti-inflammatory effects, reduces cytotoxicity, and enhances biocompatibility. Furthermore, the microneedles ensure that the drug acts directly on the infected area, increasing the local drug concentration, thereby reducing systemic side effects and accelerating the healing process.

[0017] In summary, this invention provides a novel and effective local treatment strategy by combining hollow polymeric dopamine nanoparticles with ionic liquids possessing microwave thermal effects, antibacterial properties, and anti-inflammatory functions via drug-loaded microneedles. This system not only addresses the drug resistance problem in traditional antibiotic treatment but also improves local therapeutic efficacy through precise drug delivery, while exhibiting good biocompatibility and anti-inflammatory effects. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Transmission electron microscope images of PDA, HPDA, HPDA-Van, and ILs@HPDA-Van; Figure 2 Fourier transform infrared spectrum of ILs@HPDA-Van; Figure 3 Energy dispersive X-ray spectral mapping of ILs@HPDA-Van; Figure 4 (a) is the standard curve of lipoic acid (LA); (b) is the standard curve of quaternary ammonium salt (QAC); (c) is the release curve of QAC; (d) is the release curve of QAC. Figure 5 (a) shows the microwave thermal effect of different samples at 1 mg / mL; (b) shows the microwave thermal cycling performance of ILs@HPDA-Van. Figure 6 (a) shows a planar plate photograph of different samples after treatment with Staphylococcus aureus; (b) shows a laser confocal photograph of different samples after treatment with Staphylococcus aureus with live and dead staining. Figure 7 The in vitro reactive oxygen species (ROS) scavenging capacity curve of ILs@HPDA-Van; Figure 8 This image shows the antibacterial effect of microneedle patches on a flat plate. Figure 9 Fluorescence micrographs of cell viability / death assay; Figure 10 (a) shows the statistical graph of CCK-8 experiments on RAW264.7 cells under different sample treatments; (b) shows the statistical graph of CCK-8 experiments on RAW264.7 cells under different sample treatments. Detailed Implementation

[0020] The present invention provides a drug-loaded composite nanoparticle, which includes a hollow polydopamine with vancomycin grafted on its surface and a lipoic acid-quaternary ammonium salt ionic liquid loaded into the hollow polydopamine cavity.

[0021] As one embodiment of the present invention, the preparation method of the lipoic acid-quaternary ammonium salt ionic liquid includes the following steps: mixing an anhydrous ethanol solution of lipoic acid and an anhydrous ethanol solution of quaternary ammonium salt and then evaporating to obtain the lipoic acid-quaternary ammonium salt ionic liquid.

[0022] In one embodiment of the present invention, the mass ratio of lipoic acid to quaternary ammonium salt in the lipoic acid-quaternary ammonium salt ionic liquid can be 0.5~1:1, specifically 0.55:1. In another embodiment of the present invention, the mixing can be carried out under stirring conditions, and the mixing time can be 12~24 hours, specifically 12 hours, 16 hours, 20 hours, or 24 hours; the evaporation method can be rotary evaporation; and the rotary evaporation time can be 30 minutes.

[0023] In one embodiment of the present invention, the mass ratio of the hollow polydopamine to vancomycin can be 2 to 6:4, specifically 2:4, 3:4, 4:4, 5:4 or 6:4; the mass ratio of the hollow polydopamine with vancomycin grafted on its surface to the lipoic acid-quaternary ammonium salt ionic liquid can be 1 to 5:16 to 20, specifically 1:16, 2:16, 3:16, 4:16, 5:16, 1:20, 2:20, 3:20 or 4:20.

[0024] This invention also provides a method for preparing drug-loaded composite nanoparticles according to the above-mentioned technical solution, comprising the following steps: (1) Dissolve silica nanoparticles and dopamine, and polymerize and coat the resulting solution with dopamine to obtain silica with a polydopamine shell on the surface; (2) After mixing the aqueous dispersion of silica with polydopamine shell on the surface and hydrofluoric acid solution, etching is performed to obtain hollow polydopamine; (3) Vancomycin and hollow polydopamine were mixed and grafted to obtain hollow dopamine grafted with vancomycin. (4) The lipoic acid-quaternary ammonium salt ionic liquid and the hollow dopamine grafted with vancomycin were mixed, and the resulting mixture was subjected to ultrasonic treatment and filtration in sequence to obtain drug-loaded composite nanoparticles containing lipoic acid-quaternary ammonium salt ionic liquid.

[0025] In this invention, silica nanoparticles and dopamine are dissolved, and the resulting solution is polymerized and coated with dopamine to obtain silica (denoted as PDA@SiO2) with a polydopamine (PDA) shell on the surface.

[0026] In one embodiment of the present invention, the solvent used for dissolution may be a Tris-HCl solution; the pH value of the Tris-HCl solution may be 7.6.

[0027] In one embodiment of the present invention, the polymerization and coating of dopamine involves sequentially subjecting the solution to ultrasonication and stirring; the ultrasonic power can be 40~50W, and the time can be 5~10min, specifically 5min, 6min, 7min, 8min, 9min or 10min; the stirring temperature can be room temperature, and the time can be 24~72h, specifically 24h, 48h or 72h.

[0028] In one embodiment of the present invention, after the polymerization and coating of dopamine are completed, the reaction system is further subjected to centrifugation and freeze-drying in sequence. In one embodiment of the present invention, the freeze-drying temperature can be -60°C.

[0029] After obtaining PDA@SiO2, the present invention mixes the aqueous dispersion of PDA@SiO2 with hydrofluoric acid solution and performs etching treatment to obtain hollow polydopamine (denoted as HPDA).

[0030] In one embodiment of the present invention, the concentration of the hydrofluoric acid solution can be 20~22.5 mol / L, specifically 22.4 mol / L. In another embodiment of the present invention, the etching treatment temperature can be room temperature, and the time can be 1~2 hours, specifically 1.5 hours.

[0031] In one embodiment of the present invention, after the etching process, the reaction system is further subjected to centrifugation and freeze-drying in sequence. In another embodiment of the present invention, the freeze-drying temperature can be -60°C.

[0032] After obtaining hollow polydopamine, the present invention mixes vancomycin (Van) with hollow polydopamine and performs a grafting reaction to obtain hollow dopamine grafted with vancomycin (denoted as HPDA-Van).

[0033] In one embodiment of the present invention, the vancomycin can be used in the form of a Tris solution of vancomycin; the hollow polydopamine can be used in the form of a Tris solution of hollow polydopamine.

[0034] In one embodiment of the present invention, the concentration of the Tris solution of hollow polydopamine can be 2~3 mg / mL.

[0035] In one embodiment of the present invention, the grafting reaction temperature can be room temperature, and the reaction time can be 24~48h, specifically 24h, 30h, 36h, 40h, or 48h; the grafting reaction can be carried out under stirring conditions. In another embodiment of the present invention, after grafting, the reaction system is further centrifuged and then freeze-dried.

[0036] In this invention, lipoic acid-quaternary ammonium salt ionic liquid (ILs) and HPDA-Van are mixed, and the resulting mixture is subjected to ultrasonic treatment and filtration in sequence to obtain the drug-loaded composite nanoparticles (denoted as ILs@HPDA-Van).

[0037] In one embodiment of the present invention, the HPDA-Van can be used in the form of an ethanol solution of HPDA-Van. In another embodiment of the present invention, the ultrasonic treatment power can be 45-50W, and the time can be 10-15 minutes; the filtration time can be 20 minutes.

[0038] In one embodiment of the present invention, after filtration, the solid phase is further subjected to washing with anhydrous ethanol, centrifugation, and freeze-drying. In another embodiment of the present invention, the freeze-drying temperature can be -60°C.

[0039] The present invention also provides a drug-loaded microneedle, comprising drug-loaded composite nanoparticles and a microneedle; wherein the drug-loaded composite nanoparticles are the drug-loaded composite nanoparticles described in the above technical solution or the drug-loaded composite nanoparticles prepared by the preparation method described in the above technical solution.

[0040] The present invention also provides a method for preparing the drug-loaded microneedles, comprising the following steps: After injecting a dispersion of drug-loaded composite nanoparticles into a microneedle template, the drug-loaded composite nanoparticles are coated onto the surface of the microneedle using vacuum adsorption and then dried to obtain the drug-loaded microneedle.

[0041] The present invention also provides the application of the drug-loaded composite nanoparticles described in the above technical solutions or the drug-loaded composite nanoparticles prepared by the above preparation methods, and the drug-loaded microneedles described in the above technical solutions or the drug-loaded microneedles prepared by the above preparation methods in the preparation of products for the prevention and / or treatment of subcutaneous abscesses.

[0042] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0043] The quaternary ammonium salt used in the examples, comparative examples, and tests was dodecyl dimethyl benzyl ammonium chloride.

[0044] Example 1 Preparation of ILs@HPDA-Van: 1) 200.0 mg of silica nanoparticles (SiO2) were dispersed in Tris-HCl buffer solution (100.0 mL, pH 7.6) and sonicated for 5 min. Then, 200.0 mg of dopamine was added to the above solution, and the mixture was sonicated at 50 W for 5 min and stirred at room temperature for 48 h. The solution was removed by centrifugation 4 times. The obtained solid phase was freeze-dried at -60 °C to obtain silica powder (PDA@SiO2) with polydopamine coating.

[0045] 2) 200.0 mg PDA@SiO2 was dispersed in deionized water (60.0 mL) and sonicated for 2 min. While stirring at room temperature, 800.0 μL of 22.4 mol / L hydrofluoric acid solution was added dropwise. After etching SiO2 by stirring at room temperature for 1.5 h, the solution was removed by centrifugation 4 times. The resulting solid phase was freeze-dried at -60℃ to obtain hollow dopamine powder (HPDA).

[0046] 3) 55.0 mg vancomycin (Van) was dissolved in 10.0 mL Tris-HCl buffer solution (pH 7.6), and 37.5 mg HPDA powder was dissolved in 18.0 mL Tris-HCl buffer solution. The resulting solutions were mixed and stirred at room temperature for 24 h. After centrifugation twice, the solution was removed, and the resulting solid phase was freeze-dried at -60 °C to obtain hollow dopamine nanoparticles grafted with vancomycin (HPDA-Van).

[0047] 4) 206.3 mg of lipoic acid (LA) and 372.9 mg of quaternary ammonium salt were dispersed in anhydrous ethanol solution (10.0 mL), stirred at room temperature for 24 h, and vacuum rotary evaporated for 30 min to obtain ionic liquids (ILs).

[0048] 5) Disperse 30 mg HPDA-Van in anhydrous ethanol (10.0 mL), add the ILs obtained in step 4) to the resulting solution, sonicate at 50 W for 10 min, filter for 20 min, then wash the solid phase with anhydrous ethanol, centrifuge twice to remove the solution, and freeze dry to obtain drug-loaded composite nanoparticles (ILs@HPDA-Van).

[0049] Comparative Example 1 The only difference from Example 1 is that "206.3 mg lipoic acid (LA) and 372.9 mg quaternary ammonium salt" in step 4) are replaced with "579.2 mg quaternary ammonium salt", and the final product is denoted as QAC@HPDA-Van.

[0050] Figure 1 Transmission electron microscopy images of PDA, HPDA, HPDA-Van, and ILs@HPDA-Van, from Figure 1It can be seen that SiO2 was successfully etched by hydrofluoric acid, leaving a hollow dopamine shell inside, forming hollow dopamine. In addition, the vancomycin grafting and the loading of ionic liquid did not destroy the original hollow structure.

[0051] Figure 2 The Fourier transform infrared spectrum of ILs@HPDA-Van is shown below. Figure 2 It can be seen that the HPDA-Van sample at 1500cm -1 A characteristic C=O peak appeared at 3000 cm⁻¹, and also at 3000 cm⁻¹. -1 ~3500 cm -1 The presence of NH and OH characteristic peaks indicates that vancomycin was successfully grafted onto HPDA nanoparticles.

[0052] Figure 3 The energy-dispersive X-ray spectral mapping of ILs@HPDA-Van is shown below. Figure 3 As shown in the EDS mapping figure, the characteristic signals of nitrogen (N), oxygen (O) and sulfur (S) elements were uniformly distributed in the ILs@HPDA-Van sample, which further proves that vancomycin was successfully bound to and modified on the surface of HPDA nanoparticles and that ionic liquids were successfully loaded into HPDA nanoparticles.

[0053] For the determination of ILs drug release, a standard curve was established using UV-Vis spectroscopy. ILs@HPDA-Van nanoparticles (1 mg) were dispersed in 4 mL PBS (pH=7.4) at 37 °C and shaken at 120 rpm to simulate drug release in vivo. At regular intervals, the mixture was centrifuged and analyzed using a UV-Vis spectrophotometer. 4 mL of the supernatant was then aspirated, and 4 mL of fresh buffer solution was added to continue the release of LA and QAC. The amounts of LA and QAC released from the nanoparticles were determined by their absorbance at 332 nm and 262 nm, and recorded to plot the release curve. Figure 4 (a) is the standard curve of lipoic acid (LA); (b) is the standard curve of quaternary ammonium salt (QAC); (c) is the release curve of QAC; and (d) is the release curve of QAC. The experimental results show that the multifunctional nanoparticles can achieve stable and smooth drug release in the tissue fluid environment.

[0054] To investigate the photothermal properties of different samples (normal saline, HPDA-Van, and ILs@HPDA-Van), the samples were continuously irradiated with a microwave therapy device at 40W power at room temperature for 6 minutes, with temperature changes recorded by an infrared thermal imaging camera every minute. Simultaneously, to test the stability and repeatability of the photothermal properties of the ILs@HPDA-Van samples, the samples were continuously irradiated with a microwave therapy device at room temperature for 10 minutes, followed by a 10-minute cooling period after the microwave therapy device was turned off. This was repeated four times, with temperature changes recorded by an infrared thermal imaging camera every minute throughout the process. Figure 5 As shown in (a), compared with Normal Saline, both HPDA-Van and ILs@HPDA-Van samples can be heated to about 50℃ within 6 minutes, exhibiting good photothermal conversion performance; Figure 5 As shown in (b), the ILs@HPDA-Van sample can be heated to about 60℃ in all 4 cycles of the experiment, which shows that the photothermal performance of the ILs@HPDA-Van sample is stable and repeatable.

[0055] In vitro antibacterial function test Gram-positive Staphylococcus aureus was used as a bacterial model to evaluate the antibacterial activity of nanoparticles. The bacterial suspension in the exponential growth phase was diluted to 1×10⁻⁶. 8 CFU / mL, then 375 µL of bacterial suspension was incubated with nanoparticles and sterile PBS at 37°C for 4 h (microwave group was irradiated for 20 min before incubation). Finally, the bacterial suspension was diluted with 5 mL of sterile PBS, and the resulting bacterial solution (100 µL) was evenly inoculated onto agar plates and incubated at 37°C for 16 h. The number of colonies was counted and analyzed. Figure 6 (a) is a photograph of the solid culture medium for Staphylococcus aureus, as shown in Figure 1. Figure 6 (b) shows the survival rate of Staphylococcus aureus. Under non-microwave irradiation conditions, a large number of bacteria were present on the surfaces of Control, HPDA, and HPDA-Van samples. QAC@HPDA-Van showed a significant bactericidal effect, while ILs@HPDA-Van showed a slight bactericidal effect, indicating that QAC has certain bactericidal properties. Under microwave irradiation conditions, compared with the Control, HPDA, and HPDA-Van sample groups, the ILs@HPDA-Van sample showed almost no bacterial colonies on the surface of the culture medium, with a bactericidal rate of up to 99.9%, indicating that microwave heat and ionic liquids achieve a synergistic and efficient bactericidal effect that combines physical and chemical processes.

[0056] Anti-inflammatory performance test of drug-loaded nanoparticles The antioxidant activity of nanoparticles was evaluated by scavenging 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) radicals. Specifically, various nanoparticle samples were mixed in 3 mL of DPPH ethanol solution (40 μg / mL) and reacted with each other in the dark. UV-Vis spectroscopy was used, and complete wavenumber scans were recorded at regular intervals. Here, Control represents the absorbance of the blank containing only DPPH, and Sample represents the maximum absorbance of the mixture with DPPH and various samples. Figure 7 The graph shows the in vitro reactive oxygen species (ROS) scavenging capacity of ILs@HPDA-Van. Figure 7 It can be seen that the absorbance of HPDA and HPDA-Van sample solutions decreased over time, while the absorbance of ILs@HPDA-Van sample solution decreased significantly, indicating that ILs@HPDA-Van sample has good DPPH free radical scavenging ability and excellent antioxidant capacity.

[0057] Characterization and antibacterial performance testing of drug-loaded nanoparticles incorporated into microneedles Multifunctional drug-loaded nanoparticles (HPDA, HPDA-Van, QAC@HPDA-Van, ILs@HPDA-Van) were dispersed in a suitable polyvinylpyrrolidone (PVP) solution, then immersed in a microneedle template. The composite nanoparticles were then uniformly coated onto the microneedle surface using vacuum adsorption. Subsequently, the coated microneedles were dried to obtain the final microneedle patch. The microneedle patch underwent relevant characterization experiments.

[0058] The experiment was divided into two groups: a microwave-stimulated group (MW+) and a non-microwave group (MW-), to observe the effect of microwave-assisted antibacterial efficacy. Target bacteria were evenly inoculated onto prepared agar plates, and microneedle patches were used to cover the surface of the plates for both the control and experimental groups. Samples in the MW+ group were stimulated with microwaves of a predetermined power for a preset time, while the MW- group received no microwave treatment. The plates were incubated at 37°C for 24 hours. After incubation, bacterial growth on the plates was observed and recorded, and the antibacterial effect was assessed based on the number and distribution of bacterial colonies.

[0059] Figure 8 This image shows the antibacterial effect of microneedle patches on a flat plate. Figure 8As can be seen, in the absence of microwave treatment (MW-), both QAC@HPDA-Van microneedles and ILs@HPDA-Van microneedles exhibited good antibacterial effects, significantly reducing bacterial colony counts compared to the control group and microneedles containing only HPDA. Under microwave stimulation (MW+), ILs@HPDA-Van microneedles showed a stronger antibacterial effect, almost completely inhibiting bacterial growth, further verifying the synergistic bactericidal effect of microwave thermal effect and ionic liquid. ILs@HPDA-Van microneedles demonstrate excellent antibacterial effects under microwave assistance, and the multifunctional drug-loaded nanoparticles maintain excellent bactericidal performance even after being loaded into the microneedle system.

[0060] Cell biocompatibility evaluation of multifunctional nanoparticle microneedle patches Acetylmethyl ester (AM) and propidium iodide (PI) dyes were used to label live and dead cells. Cells treated with microneedle patches (HPDA, HPDA-Van, QAC@HPDA-Van, ILs@HPDA-Van) were seeded onto culture plates, and experiments were performed on samples from each group. After 24 hours of culture, cells were stained with AM and PI dyes; AM labeled live cells, and PI labeled dead cells. The stained cells were photographed using a fluorescence microscope, and the green (live cells) and red (dead cells) fluorescence signals of each group were observed and recorded. It can be seen that the control group and each experimental group (HPDA-MN, HPDA-Van-MN, QAC@HPDA-Van-MN, ILs@HPDA-Van-MN) had a higher proportion of live cells (green) and fewer red signals (dead cells), indicating that the multifunctional drug-loaded nanoparticle microneedles have low cytotoxicity.

[0061] Cell proliferation and toxicity were assessed using a CCK-8 assay kit to evaluate cell viability. CCK-8 cell viability assays included... Figure 10 ( Figure 10 (a) shows the statistical graph of CCK-8 assays for RAW264.7 cells under different sample treatments; (b) shows the statistical graph of CCK-8 assays for RAW264.7 cells under different sample treatments. Cells were seeded into 96-well plates and cultured for 24 hours. Then, microneedle patch (HPDA, HPDA-Van, QAC@HPDA-Van, ILs@HPDA-Van) treatment solutions were added, and incubation continued for another 24 hours. CCK-8 reagent was added, and the cells were cultured at 37℃ for 1-2 hours. Absorbance was measured at 450 nm using a microplate reader to calculate cell viability. The results showed that cell viability in all experimental groups was above 80%, further indicating good biocompatibility of the microneedle samples.

[0062] Data from the embodiments demonstrate that this invention constructs a multifunctional microneedle drug delivery system with microwave-responsive ionic liquid-based antibacterial and anti-inflammatory functions. The system uses HPDA nanoparticles as its core, whose hollow structure provides sufficient space for drug molecule loading. Vancomycin (Van) is chemically grafted onto the surface, further enhancing the antibacterial ability and ensuring a sustained antibacterial effect during delivery. Furthermore, the minimally invasive penetration characteristics of the microneedle system enable precise local drug delivery. The ionic liquid components include quaternary ammonium salt (QAC) and lipoic acid (LA). QAC generates a significant thermal effect under microwave stimulation, synergistically enhancing the antibacterial effect in conjunction with its chemical bactericidal action. Lipoic acid (LA) possesses excellent free radical scavenging capabilities, playing a significant role in inhibiting local inflammation and thus providing an anti-inflammatory effect.

[0063] In summary, the materials used in this invention all possess excellent biocompatibility, and combined with the effective delivery of the microneedle system, they achieve both safety and high efficiency in local treatment. This microwave-thermally responsive ionic liquid-based drug-loaded microneedle exhibits both long-lasting bactericidal and anti-inflammatory functions, demonstrating promising clinical application prospects.

[0064] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Drug-loaded composite nanoparticles, characterized in that, The hollow polydopamine comprises vancomycin grafted on the surface, and the liponic acid-quaternary ammonium salt ionic liquid is loaded in the cavity of the hollow polydopamine.

2. The drug-loaded composite nanoparticle of claim 1, wherein, The mass ratio of the liponic acid and the quaternary ammonium salt in the liponic acid-quaternary ammonium salt ionic liquid is 0.5-1:1; the quaternary ammonium salt comprises one or more of dodecyl dimethyl benzyl ammonium chloride, dipenta decyl dimethyl ammonium chloride and trioctyl methyl ammonium chloride.

3. The drug-loaded composite nanoparticles as described in claim 1, characterized in that, The mass ratio of the hollow polydopamine with vancomycin grafted on the surface and the liponic acid-quaternary ammonium salt ionic liquid is 1-5:16-20. The mass ratio of the hollow polydopamine and vancomycin is 2-6:

4.

4. The drug-loaded composite nanoparticle of any one of claims 1-3, wherein the drug is a small molecule drug. The preparation of the liponic acid-quaternary ammonium salt ionic liquid comprises the following steps: mixing the liponic acid anhydrous ethanol solution and the quaternary ammonium salt anhydrous ethanol solution, and then evaporating to obtain the liponic acid-quaternary ammonium salt ionic liquid.

5. The method of preparing drug-loaded composite nanoparticles according to any one of claims 1 to 4, characterized in that, The preparation method comprises the following steps: (1) dissolving the silica nanoparticles and dopamine to obtain a solution, and then polymerizing and coating the dopamine to obtain silica with a polydopamine shell; (2) mixing the water dispersion of the silica with the polydopamine shell and a hydrofluoric acid solution, and then performing etching treatment to obtain hollow polydopamine; (3) mixing vancomycin and the hollow polydopamine, and then performing grafting reaction to obtain hollow polydopamine with vancomycin grafted thereon; (4) mixing the liponic acid-quaternary ammonium salt ionic liquid and the hollow polydopamine with vancomycin grafted thereon, and then performing ultrasonic treatment and suction filtration on the obtained mixture in sequence to obtain the drug-loaded composite nanoparticles.

6. The production method according to claim 5, wherein The concentration of the hydrofluoric acid solution is 20-22.5 mol / L; the etching treatment is performed at room temperature for 1-2 h.

7. The production method according to claim 5, wherein The grafting reaction is performed at room temperature for 24-48 h; The ultrasonic treatment is performed at a power of 40-50 W for 10-15 min.

8. A drug-loaded microneedle, characterized by, The drug-loaded composite nanoparticles are the drug-loaded composite nanoparticles of any one of claims 1-4 or the drug-loaded composite nanoparticles prepared by the preparation method of any one of claims 5-7.

9. The method of claim 8, wherein the drug-loaded microneedle is prepared by, The preparation method comprises the following steps: After the dispersion of the drug-loaded composite nanoparticles is injected into the microneedle template, the drug-loaded composite nanoparticles are coated on the surface of the microneedle by vacuum adsorption, and then dried to obtain the drug-loaded microneedle.

10. The drug-loaded composite nanoparticles of any one of claims 1-4 or prepared by the preparation method of any one of claims 5-7, the drug-loaded microneedle of claim 8 or prepared by the preparation method of claim 9 are used for preparing a product for preventing and / or treating subcutaneous abscess.

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