A selective sterilization cationic carbon quantum dot porphyrin porous organic polymer and a preparation method and application thereof

Abstract

The application discloses a kind of selective sterilization cationic carbon quantum dot porphyrin porous organic polymer and preparation method and application thereof, belong to biological medicine technical field.The cationic carbon quantum dot porphyrin porous organic polymer with several aldehyde groups carbon quantum dots and with methyl pyridine ring porphyrin as structural unit, by Knoevenagel condensation form porous polymer, and pyridine nitrogen atom in porphyrin and alkyl iodine form N-methyl pyridine onium cation, iodine ion as counterion.The aldehyde group functionalized carbon quantum dots are used as three-dimensional covalent node and steric hindrance control unit in the application, so that tetra (6-methyl pyridine-3-yl) porphyrin is fixed around carbon quantum dot and forms carbon-carbon double bond containing covalent connection structure;Subsequently, pyridine nitrogen is N-methylated using iodomethane;Overcome the problems that porphyrin is easy to aggregate and quench in the existing light response antibacterial material, active oxygen species is difficult to control and the problem of insufficient sterilization selectivity.

Description

Technical Field

[0001] This invention relates to the field of biomedical technology, specifically to a selectively bactericidal cationic carbon quantum dot porphyrin porous organic polymer, its preparation method, and its application. Background Technology

[0002] The increasing prevalence of multidrug-resistant bacterial infections has become one of the most pressing threats to global public health. Traditional antibiotics, the cornerstone of antimicrobial therapy, are becoming increasingly ineffective due to the continuous spread of resistance genes, while their broad-spectrum activity often disrupts native microbial ecosystems and causes off-target toxicity to host tissues. This dual dilemma—ineffectiveness against drug-resistant pathogens and collateral damage to the host—calls for innovative treatment modalities capable of precisely eliminating pathogens while preserving beneficial symbiotic flora and surrounding healthy cells.

[0003] Among clinically relevant pathogens, Staphylococcus aureus (S. aureus) is a major causative agent in chronic, non-healing wounds, implant-related infections, and biofilm-related diseases. Its ability to colonize skin and mucosal surfaces, coupled with the rise of methicillin-resistant Staphylococcus aureus (MRSA), makes it an ideal target for precision antimicrobial therapy. Importantly, selectively eliminating S. aureus offers dual benefits. Specifically, it can directly reduce the infection burden without depleting protective commensal bacteria crucial for maintaining skin barrier integrity and preventing the overgrowth of opportunistic pathogens such as Clostridium difficile. Therefore, a treatment strategy capable of distinguishing Gram-positive pathogens (such as S. aureus) from other bacterial species while remaining harmless to mammalian cells would represent a significant advancement in infection management. Photodynamic therapy (PDT) and photothermal therapy (PTT) have attracted considerable attention as non-invasive, spatiotemporally controlled alternatives due to their lower likelihood of inducing resistance. However, a major obstacle to their clinical application is the lack of targeted specificity. Most phototherapy drugs generate large amounts of highly reactive oxygen species (ROS) or heat upon activation, indiscriminately attacking pathogens and host cells, leading to local inflammation, delayed wound healing, and damage to the skin microbiome. For example, patent application CN118420856A discloses a five-in-one antibacterial porphyrin cationic covalent organic framework material and its preparation method. First, tetrakis(6-methylpyridin-3-yl)porphyrin and octaaldehyde porphyrin are polymerized to obtain a COF, which is then reacted with iodomethane to obtain the five-in-one antibacterial porphyrin cationic covalent organic framework material. Although this material has five antibacterial modes, its antibacterial activity lacks selectivity: it can kill both Gram-positive and Gram-negative bacteria. This non-specificity not only narrows the therapeutic window but may also promote secondary opportunistic infections, a consequence often overlooked in the design of antibacterial materials.

[0004] Carbon quantum dots (CDs), also known as carbon dots or carbon nanodots, are a class of zero-dimensional carbon nanomaterials with remarkable fluorescence properties. They consist of ultrafine, dispersed, quasi-spherical carbon nanoparticles with a size of less than 10 nm. Due to their tunable optical properties, excellent biocompatibility, and surface functionalization capabilities, they have become an attractive photosensitization platform. However, pristine carbon quantum dots suffer from problems such as aggregation-induced quenching, short retention time, and uncontrollable systemic distribution, which reduce their photosensitivity. Incorporating carbon quantum dots into polymer matrices has been explored to address these issues, but most existing carbon quantum dot-polymer hybrids still generate various highly oxidizing reactive oxygen species (such as singlet oxygen, hydroxyl radicals, and superoxide anions) under light irradiation, leading to the same non-specific damage as traditional photosensitizers. For example, the paper "Carbondots as an electron extractant for enhanced photocatalytic antibacterial activity of covalent organic frameworks" (Liang et al., Journal of Materials Chemistry A, 2022) incorporates carbon dioxide (CDs) into carbon-containing fossil fuels (COFs). However, this paper loads carbon quantum dots onto the COF surface via hydrogen bonds, and simultaneously generates O2. •- , 1 O2 and •OH, among other ROS, possess broad-spectrum antibacterial properties. Therefore, how to introduce carbon quantum dots into COF while avoiding the quenching of carbon quantum dots and achieving selective clearance of pathogenic bacteria is a problem that needs to be solved. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a selectively bactericidal cationic carbon quantum dot porphyrin porous organic polymer, its preparation method, and its applications. This invention utilizes aldehyde-functionalized carbon quantum dots as three-dimensional covalent nodes and steric hindrance control units, immobilizing tetrakis(6-methylpyridin-3-yl)porphyrin around the carbon quantum dots to form a covalently linked structure containing carbon-carbon double bonds. Subsequently, iodomethane is used to N-methylate the pyridine nitrogen, giving the polymer stable pyridinium cation sites and iodide counterions. This overcomes the problems of easy aggregation and quenching of porphyrins, difficulty in controlling the types of reactive oxygen species, and insufficient bactericidal selectivity in existing photoresponsive antibacterial materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a selectively bactericidal cationic carbon quantum dot porphyrin porous organic polymer (MP-CD-I), which uses carbon quantum dots with several aldehyde groups and porphyrin with methylpyridine rings as structural units, and forms a porous polymer by Knoevenagel condensation. In this polymer, the pyridine nitrogen atom in the porphyrin undergoes an N-alkylation reaction with an alkyl iodine to form an N-alkylpyridinium cation, with the iodine ion acting as the counterion.

[0007] Preferably, the porphyrin with a methylpyridine ring is tetrakis(6-methylpyridin-3-yl)porphyrin; and the alkyl iodine is iodomethane.

[0008] Preferably, the polymer has a hierarchical pore structure consisting of micropores and mesopores.

[0009] A second aspect of the present invention provides a method for preparing a cationic carbon quantum dot porphyrin porous organic polymer, comprising the following steps: (1) Add glutaraldehyde and anhydrous ethanol into a high-pressure container, heat and cool, disperse the resulting solid in acetone and chloroform in sequence and centrifuge to remove high molecular weight carbon aggregates, and distill under reduced pressure to obtain carbon quantum dots with several aldehyde groups, denoted as CDs; (2) Mix CDs and tetra(6-methylpyridin-3-yl)porphyrin, add 1,4-dioxane and mesitylene, stir thoroughly, add trifluoroacetic acid for solvothermal reaction, cool to room temperature after the reaction is completed, filter to separate the solid product, wash, and the carbon quantum dot porphyrin porous organic polymer obtained is denoted as MP-CD; (3) Disperse MP-CD in acetone, add excess iodomethane, heat and stir to carry out the reaction, filter, wash and dry to obtain selectively bactericidal cationic carbon quantum dot porphyrin porous organic polymer MP-CD-I.

[0010] Preferably, in step (1), the volume ratio of glutaraldehyde to anhydrous ethanol is 1:2; the heating treatment temperature is 150°C and the time is 2h.

[0011] Preferably, in step (2), the mass ratio of CDs to tetra(6-methylpyridin-3-yl)porphyrin is 3:2; and the volume ratio of 1,4-dioxane, mesitylene and trifluoroacetic acid is 10:10:3.

[0012] Preferably, in step (2), the temperature of the solvothermal reaction is 180°C and the time is 72h; the washing includes washing with N,N-dimethylformamide, methanol, dichloromethane and dimethyl sulfoxide in sequence until the filtrate is clear.

[0013] Preferably, in step (3), the ratio of the amount of MP-CD and iodomethane added is 100 mg: 1~3 mL; the heating and stirring temperature is 40°C and the time is 24 h.

[0014] A third aspect of the present invention provides the use of cationic carbon quantum dot porphyrin porous organic polymers in the preparation of selectively bactericidal antibacterial drugs.

[0015] Preferably, the selective sterilization is the killing of Gram-positive bacteria; the Gram-positive bacteria is Staphylococcus aureus.

[0016] The beneficial effects of this invention are: (1) The carbon quantum dots of the present invention simultaneously play the roles of covalent bonding, steric hindrance, and electronic regulation, enabling the porphyrin units to be distributed in a confined manner, reducing the tight π-π stacking and aggregation-induced quenching between porphyrin planes. The conjugated connection between carbon quantum dots and porphyrins, together with the quaternized pyridinium structure, regulates excited-state relaxation and charge transfer, making the material detectable with superoxide anion radicals but not with singlet oxygen and hydroxyl radicals, thus reducing non-specific damage caused by mixed highly reactive oxygen species.

[0017] (2) The pyridinium cation of the present invention can electrostatically adsorb onto the negatively charged bacterial surface, concentrating the photothermal and superoxide anion free radical interactions at the bacterial interface, reducing heat loss and diffusion loss of short-lived active species. The material exhibits concentration- and light power-dependent heating behavior under 638 nm light irradiation and remains stable after multiple switching cycles, and can synergize with the photodynamic effects mediated by superoxide anions.

[0018] (3) This invention can significantly reduce the amount of Staphylococcus aureus biofilm and destroy its three-dimensional structure, while having a low hemolysis rate, a high fibroblast survival rate and good in vivo safety. In a mouse model of full-thickness skin wounds infected with Staphylococcus aureus, the wound closure rate reached approximately 98.8% on day 9, promoting re-epithelialization and collagen deposition. Attached Figure Description

[0019] Figure 1 Synthesis route diagram of MP-CD-I; Figure 2 FTIR spectra of CDs, TMPP, MP-CD and MP-CD-I; Figure 3 MP-CD-I solid state 13 C NMR spectrum; Figure 4 Powder XRD pattern of MP-CD-I; Figure 5 (a) Low-temperature N2 adsorption isotherm of MP-CD-I at 77 K; (b) Pore size distribution curve of MP-CD-I; Figure 6 TGA of MP-CD-I under nitrogen atmosphere; Figure 7 Morphological characteristics and elemental analysis of MP-CD-I; (a) Scanning electron microscope (SEM) image of MP-CD-I at a scale bar of 100 nm; (b) Scanning electron microscope (SEM) image of MP-CD-I at a scale bar of 500 nm; (c) Transmission electron microscope (TEM) image of MP-CD-I at a scale bar of 0.5 μm; (d) Transmission electron microscope (TEM) image of MP-CD-I at a scale bar of 50 nm; (e) High-resolution transmission electron microscope (HR-TEM) image of MP-CD-I at a scale bar of 5 nm; (f) Elemental distribution map of MP-CD-I; Figure 8 EDS spectrum of MP-CD-I; Figure 9 The photodynamic and photothermal properties of MP-CD-I and the control group were compared. (a) Time-dependent fluorescence spectra of DHR123 in the presence of MP-CD-I under 638 nm laser irradiation; (b) Time-dependent fluorescence spectra of DHR123 in the presence of MP-CD under 638 nm laser irradiation; (c) Quantitative comparison of normalized DHR123 fluorescence intensity (A / A0) at 525 nm; (d) Temperature rise curves corresponding to MP-CD-I dispersion concentrations (0–450 μg / mL) under 638 nm laser irradiation; (e) Different laser power densities (0.5–1.5 W / cm²). 2 (f) Temperature rise curve of MP-CD-I (150 μg / mL); (g) Infrared thermal imaging of MP-CD-I dispersions (0, 75, 150, 300 and 450 μg / mL); (h) Photothermal cycling stability test of MP-CD-I in four consecutive on-off irradiation cycles; (f) Natural cooling process of MP-CD-I after a single heating. Figure 10 (a) MP-CD-I induced under dark or 638 nm laser irradiation conditions. 1 (a) EPR spectrum of O2; (b) EPR spectrum of •OH induced by MP-CD-I under dark or 638 nm laser irradiation conditions; (c) EPR spectrum of O2 induced by MP-CD-I under dark or 638 nm laser irradiation conditions. •- EPR spectrum; Figure 11 (a) UV-Vis absorption spectra of MP-CD at different concentrations; (b) UV-Vis absorption spectra of MP-CD-I at different concentrations; Figure 12 (a) Staphylococcus aureus irradiated with a 638 nm laser (1.5 W / cm²) 2(a) Colony photographs after treatment with different concentrations of MP-CD-I (0–150 μg / mL) at 10 minutes; (b) Quantitative survival rate of Staphylococcus aureus after corresponding treatments; (c) Colony photographs of Staphylococcus aureus after treatment in each group; (d) Quantitative survival rate of Staphylococcus aureus after treatment in each group; All error bars represent mean ± standard deviation (n = 3). Figure 13 (a) The comprehensive antibacterial activity of MP-CD-I against Escherichia coli at different concentrations (0–500 μg / mL) under 638 nm laser irradiation; (b) The corresponding quantitative analysis results of MP-CD-I against Escherichia coli at different concentrations (0–500 μg / mL); (c) The comprehensive antibacterial activity of MP-CD against Escherichia coli at different concentrations (0–500 μg / mL); (d) The quantitative results of the antibacterial activity of MP-CD against Escherichia coli at different concentrations. Figure 14 (a) Fluorescence microscopy images of Staphylococcus aureus stained with SYTO 9 / PI after different treatments; (b) Fluorescence microscopy images of Escherichia coli stained with SYTO 9 / PI after different treatments; (c) Representative transmission electron microscopy images of the changes in ultrastructure of Staphylococcus aureus after different treatments, all with a scale bar of 2 μm; (d) Representative transmission electron microscopy images of the changes in ultrastructure of Escherichia coli after different treatments, all with a scale bar of 2 μm. Figure 15 (a) Quantitative analysis of Staphylococcus aureus biofilm quality after treatment in each group using CV staining; (b) Quantitative analysis of Escherichia coli biofilm quality after treatment in each group using CV staining; (c) CLSM three-dimensional reconstruction images of Staphylococcus aureus and Escherichia coli biofilms after treatment in each group; (d) Quantitative mean fluorescence intensity (MFI) analysis of Staphylococcus aureus biofilm after treatment in each group; (e) Quantitative mean fluorescence intensity (MFI) analysis of Escherichia coli biofilm after treatment in each group; All error bars represent mean ± standard deviation (n = 3). Figure 16 Evaluation of the in vitro biocompatibility of MP-CD-I; including (a) the hemolytic activity of MP-CD-I; and (b) the cytotoxicity of MP-CD-I on NIH 3T3 cells. Figure 17 Evaluation of in vivo wound healing and biocompatibility of MP-CD-I; (a) wound images of each group during treatment; (b) quantitative wound closure rate within 9 days; (c) weight changes in each group; (d) skin H&E staining and Masson trichrome staining on day 9; data are mean ± standard deviation (n=3). Detailed Implementation

[0020] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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 application pertains.

[0021] As described in the background section, existing carbon quantum dot-polymer photosensitive systems typically generate multiple reactive oxygen species, such as singlet oxygen, hydroxyl radicals, and superoxide anions, under light irradiation, which may still cause non-specific oxidative damage.

[0022] Based on this, the purpose of this invention is to provide a selectively bactericidal cationic carbon quantum dot porphyrin porous organic polymer, its preparation method, and its applications. This invention first synthesizes a parent framework MP-CD by solvothermal condensation of CDs and TMPP in a two-solvent system of 1,4-dioxane and mesitylene under acidic catalysis. Benefiting from the high density of aldehyde sites on the CD backbone, the porphyrin units are arranged in a highly compact manner, producing a significant steric hindrance effect, forcing the chromophores into a non-π-π stacked, face-up configuration. This steric confinement effectively suppresses aggregation-induced quenching (ACQ) and establishes a specific superoxide radical (O2) target. •- The resulting heterojunction structure was then quaternized with iodomethane to introduce a positively charged pyridinium cation group, thus yielding the final MP-CD-I. This cation engineering not only significantly enhanced bacterial adhesion through electrostatic interactions but also optimized the excited-state energy transfer pathway, thereby achieving highly efficient photothermal and photodynamic synergistic therapy.

[0023] In this invention, the aldehyde groups retained on the surface of carbon quantum dots can condense with methylpyridylporphyrin, thereby integrating the three-dimensional spatial structure of carbon quantum dots, the photosensitive units of porphyrin, and the conjugated connection structure into the same framework. The cationic carbon quantum dot-porphyrin porous organic polymer is preferably an amorphous porous organic polymer. The amorphous state does not affect its structural stability as a porous covalent network, and the carbon quantum dot nodes and disordered covalent connections can form a hierarchical structure with micropores, mesopores, and interparticle pores, which is beneficial for mass transfer between oxygen, reactive oxygen species, and bacterial interfaces. Carbon quantum dots simultaneously play a role in covalent connection, steric hindrance, and electronic regulation, causing the porphyrin units to be distributed in a confined manner, reducing the tight π-π stacking and aggregation-induced quenching between porphyrin planes. The conjugated connection between carbon quantum dots and porphyrin, along with the quaternized pyridinium structure, regulates excited-state relaxation and charge transfer. Under the detection conditions of this invention, only superoxide anion radicals are detected, while singlet oxygen and hydroxyl radicals are not. This reduces non-specific damage caused by mixed highly reactive oxygen species, resulting in MP-CD-I having a significantly higher bactericidal effect against Gram-positive bacteria like Staphylococcus aureus than against Gram-negative bacteria like Escherichia coli. Both carbon quantum dots and porphyrins are easily quenched. The polymerization method of this invention avoids the quenching of both carbon quantum dots and porphyrins, primarily generating superoxide anion radicals with relatively mild oxidizing power. Compared to other ROS species, this selective O2... •- The generation of O2 has significant advantages. Unlike •OH, which has an extremely high oxidation potential (E0 ≈ 2.8 V) and reacts nonselectively with almost all biomolecules at a diffusion-controlled rate, O2... •- It exhibits a milder redox potential (E0 ≈ 0.94 V) and preferentially shows reactivity to specific targets. Similarly, although 1 O2 is a strong electrophilic oxidant that can react with a variety of unsaturated lipids, proteins, and nucleic acids, but O2 •- It exhibits more limited reactivity, primarily functioning as a moderate reducing and oxidizing agent in biological systems. O2 •- This inherent chemoselectivity directly translates into a biological therapeutic window, where isooxidative intensity can be effectively neutralized by cells with strong antioxidant defenses (such as superoxide dismutase, SOD), but is lethal to organisms with weak antioxidant capacity. Therefore, MP-CD-I is effective against O2. •- The controlled generation not only avoids the indiscriminate oxidative damage usually associated with mixed-ROS photosensitizers, but also utilizes the different antioxidant capacities of different bacterial species, thus establishing a molecular basis for selective bactericidal behavior.

[0024] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.

[0025] Unless otherwise specified, the pH of the PBS used in this invention is 5.5.

[0026] The test materials used in the embodiments of this invention are all conventional test materials in the art and can be purchased through commercial channels.

[0027] Example 1: Preparation of MP-CD-I (1) Preparation of CDs: 300 μL of glutaraldehyde (50%, Maclean) and 600 μL of anhydrous ethanol were added to a pressure-resistant reaction vessel, sealed, and placed in an oven at 150℃ for 2 h. After cooling, the resulting brown solid was redispersed in acetone and chloroform in sequence, and centrifuged at 10000 rpm for 15 min to remove the high molecular weight carbon aggregates; each solvent was purified three times. The supernatant was evaporated under reduced pressure to remove the solvent, and the brown carbon dot solids with aldehyde groups on the surface were obtained and denoted as CDs.

[0028] (2) Preparation of tetra(6-methylpyridin-3-yl)porphyrin TMPP 7.20 g of 3-formyl-6-methylpyridine (59.50 mmol, 98%, Leyan) and 150 mL of propionic acid were added to a reaction flask. Under stirring, 4.11 mL (59.50 mmol) of freshly distilled pyrrole was added dropwise through a constant-pressure dropping funnel. The mixture was heated to 140 °C and refluxed for 1.5 h. After cooling to room temperature, propionic acid was removed under reduced pressure. The residue was washed and neutralized with saturated sodium bicarbonate solution to remove acidic impurities. The crude product was subjected to silica gel column chromatography using dichloromethane / methanol at a volume ratio of 20:1 to obtain a purple crystalline solid, which was TMPP, in 9.4% yield.

[0029] (3) Preparation of carbon quantum dot-porphyrin porous organic polymer MP-CD Add 150 mg of CDs and 100 mg of TMPP to a reaction flask, followed by 2 mL of 1,4-dioxane and 2 mL of mesitylene. After thorough stirring and dispersion, slowly add 0.6 mL of trifluoroacetic acid (completely added dropwise over 10 min). Seal the reaction flask in a PTFE-lined reactor and react at 180 °C for 72 h. After cooling, filter and collect the solid. Wash the solid repeatedly with N,N-dimethylformamide (DMF), methanol, dichloromethane (DCM), and dimethyl sulfoxide (DMSO) sequentially until the filtrate is clear, indicating that residual impurities and unreacted starting materials have been completely removed. The final product is a black powder, named MP-CD.

[0030] (4) Preparation of cationic carbon quantum dot-porphyrin porous organic polymer MP-CD-I 100 mg of MP-CD was dispersed in acetone (10 mL), and 1 mL of iodomethane was slowly added dropwise (completed within 15 min). The mixture was stirred at 40 °C for 24 h. After the reaction was complete, the mixture was thoroughly washed with acetone and pure water to obtain a black powder, MP-CD-I. The synthetic route is as follows: Figure 1 As shown.

[0031] Example 2: Characterization (1) It was first used to verify the chemical structure of MP-CD-I, and compared with CDs, TMPP, MP-CD and MP-CD-I prepared in Example 1. The results are as follows: Figure 2 As shown, the FT-IR spectrum of MP-CD-I simultaneously reveals the characteristic signals of both the original CDs and the TMPP monomers. Compared to the precursor, MP-CD-I exhibits aldehyde (–CHO) stretching vibrations in the range of 1680–1720 cm⁻¹. -1 The effect was significantly reduced at approximately 1660 cm⁻¹, which is attributed to surface-modified CDs and is accompanied by [a decrease in concentration at approximately 1660 cm⁻¹]. -1 The new peak appearing at this point is attributed to the conjugated –C=C– double bond formed by Knoevenagel condensation. The characteristic skeletal vibrations of the porphyrin macrocycle occur at approximately 1500 cm⁻¹. -1 (Aromatic C=C stretching) and 1350 cm -1 (The C–N stretching of the pyrrole unit) is preserved at approximately 800 cm. -1 A distinct C–H bending vibration of the substituted benzene ring is observed at this location. Furthermore, through [the location] at approximately 1470–1480 cm [the point is missing in the original text]. -1 The strong absorption band at the point confirms the success of the tetrasubstituted reaction; this absorption band is attributed to C–N. + Symmetrical stretching vibration, and at approximately 2920 cm -1 Approximately 2850 cm -1 N appears at the location + Aliphatic C–H stretching bands linking methyl groups. Overall, these spectral changes clearly confirm the successful condensation reaction between CDs and TMPP, while preserving the aromaticity of porphyrins and introducing dense cationic sites.

[0032] (2) Solid state 13 C-cross polarized magic-angle rotation (CP / MAS) nuclear magnetic resonance spectroscopy is further used to resolve the composition of the carbon framework, such as... Figure 3 As shown, 13 The C10 NMR spectrum showed broad peaks spanning from the unsaturated carbon region to the saturated carbon region. Specifically, the characteristic peak at 52.9 ppm is attributed to the methyl carbon (–N) in the N-methylpyridinium group. +–CH3), confirming successful methylation. The signal in the 100–140 ppm range corresponds to the aromatic carbon of the porphyrin unit and the carbon dot skeleton, indicating that the porphyrin is effectively bound to the skeleton. Furthermore, the resonance at approximately 160 ppm is attributed to the aromatic carbon bound to the cationic nitrogen atom, further verifying the condensation reaction between the carbon dot and TMPP.

[0033] (3) The powder X-ray diffraction pattern of MP-CD-I only shows broad and diffuse scattering peaks, without obvious sharp Bragg diffraction peaks, such as Figure 4 As shown, the obtained material is an amorphous covalent porous network.

[0034] (4) Figure 5 (a) The 77 K nitrogen adsorption-desorption results for MP-CD-I show that MP-CD-I exhibits both microporous and mesoporous adsorption characteristics, with a BET specific surface area of ​​32.7 m². 2 / g, total pore volume is 0.039 cm³ 3 / g; the pore size distribution shows a predominantly microporous peak at approximately 1.8 nm, mesoporous characteristics at approximately 12.5 nm, and interparticle pores larger than 50 nm. The adsorption isotherm exhibits type I / IV bonding characteristics, showing significant adsorption at low P / P0, indicating a large number of micropores, while gradually increasing at higher relative pressures, attributed to the presence of mesopores. Small hysteresis loops suggest uniform pore connectivity, while the stable increase in adsorption capacity at extremely high pressures reveals the presence of macropores. Figure 5 (b) This demonstrates that the hierarchical pore structure was quantitatively verified through pore size distribution, with the results showing a predominance of micropore peaks and the presence of some mesopores. The measured specific surface area and total pore volume of Brunauer–Emmett–Teller (BET) were 32.7 m². 2 g -1 and 0.039 cm 3 g -1 This highlights the highly accessible porous nature of the framework. From a thermodynamic perspective, this hierarchical porous structure serves a dual purpose. Micropores create a confined environment conducive to the stability of photoinduced charge carriers, while mesopores and macropores facilitate unimpeded molecular transport and substrate diffusion, thereby enhancing their accessibility to active sites.

[0035] (5) The thermal stability of MP-CD-I was evaluated by thermogravimetric analysis (TGA) under nitrogen atmosphere from room temperature to 800 °C. Figure 6The TGA curves revealed a multi-step degradation process, with a slight weight loss of approximately 3.34% observed below 100 °C, attributed to the removal of physically adsorbed water. A significant decomposition then occurred between 100 and 200 °C, with a mass decrease of 6.96% (from 96.6% to 89.7%), likely corresponding to the evaporation of residual solvent. Upon further heating to 800 °C, an additional 53.6% weight loss was recorded, leaving a remaining mass of 36.1%. This final stage can be attributed to the gradual degradation of organic links and partial carbonization of carbon quantum dots. The substantial carbonaceous residue (36.1%) indicates a stable hybrid framework with high structural integrity. These results collectively suggest that MP-CD-I possesses moderate to high thermal stability, making it suitable for practical therapeutic applications involving localized photothermal heating.

[0036] (6) The morphology and pore structure of MP-CD-I were first examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For example... Figure 7 (a) and Figure 7 As shown in (b), the SEM image reveals an irregular, blocky material with a three-dimensional aggregated morphology, composed of tightly packed nanoparticle assemblies. This particle aggregation characteristic is observed through... Figure 7 (c) and Figure 7 (d) was further confirmed by TEM, which revealed a loosely interconnected network structure with abundant voids distributed throughout the matrix. Notably, the micrographs clearly revealed a hierarchical porous structure in which mesopores and macropores coexist, forming continuous channels throughout the entire framework. Figure 7 (e) High-resolution transmission electron microscopy (HR-TEM) imaging further revealed the widespread micropores in MP-CD-I, as seen in localized contrast variations. These observations are consistent with the pore size distribution curves obtained from nitrogen adsorption analysis. This hierarchical structure integrates the CDs-reinforced framework with interconnected macropores, facilitating efficient charge separation and rapid mass transport while maintaining structural robustness. Furthermore, Figure 8 Energy dispersive X-ray spectroscopy and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) elemental mapping in Figure 7(f) show that the mass percentage contents of C, N, O and I are 62.17%, 9.74%, 2.81% and 25.28%, respectively, which clearly verifies the successful introduction of porphyrin units and the uniform distribution of heteroatoms.

[0037] Example 3: Photodynamic and Photothermal Properties (1) Photodynamic performance Detection was performed using the non-fluorescent dye dihydrorhodamine (DHR123). · O2 -The dye is oxidized by superoxide anions to form rhodamine 123. During this oxidation reaction, the superoxide anion breaks the unsaturated bonds in DHR123, leading to a structural change and subsequent fluorescence. 3 μL of DHR123 (5 mM dissolved in DMSO) was added to MP-CD-I or MP-CD solution (150 μg / mL, pH 5.5 PBS), and the mixture was irradiated with a 638 nm laser for different time periods. Fluorescence emission was then measured using a fluorescence spectrophotometer at an excitation wavelength of 495 nm, and the emission spectrum was recorded between 500 and 600 nm, with a characteristic peak observed at 526 nm.

[0038] As shown in Figure 9(a), MP-CD-I exhibited gradual fluorescence quenching under illumination, while the fluorescence of the ROS-sensitive probe DHR123 was significantly enhanced. In contrast, Figure 9(b) shows that MP-CD exhibited significantly different spectral evolution curves under the same conditions, indicating that structural modification, particularly the introduction of the cationic moiety, profoundly altered the excited-state relaxation pathway. Quantitative analysis in Figure 9(c) further reveals that MP-CD-I mediated a significantly faster increase in the normalized absorbance (A / A0) of DHR123 compared to MP-CD and free DHR123. Notably, under the same irradiation conditions, the fluorescence intensity of MP-CD-I was approximately twice that of MP-CD, highlighting the crucial role of the cationic framework in promoting ROS generation efficiency. This accelerated and enhanced ROS production kinetics suggests that cationic modification not only promotes electrostatic bacterial targeting but also plays a key role in regulating electronic configuration, thereby facilitating more efficient energy transfer from the photosensitizer to molecular oxygen. It is noteworthy that under the same irradiation conditions, no other probes showed detectable signal changes. This probe-dependent response difference strongly suggests that the ROS generated by MP-CD-I is highly specific, rather than a mixture of multiple oxide species.

[0039] To clearly verify this selective photodynamic behavior and further explore its potential charge transfer mechanism, electron paramagnetic resonance (EPR) spin trapping experiments were conducted using 5,5-dimethyl-1-pyrrolline N-oxide (DMPO) as a radical species trapping agent. Figure 10 As shown, the corresponding DMPO–O2 was clearly observed under irradiation. •- The characteristic sextet signal of the adduct confirmed the formation of the superoxide anion. Crucially, no DMPO–•OH signal was detected under the same conditions, clearly ruling out the involvement of hydroxyl radicals in the photocatalytic process. For the detection of singlet oxygen, 2,2,6,6-tetramethylpiperidine (TEMP) was used as a spin trapping agent, which, along with… 1The O2 reaction forms a stable nitro-oxygen radical, TEMPO. Consistent with the chemical probe results, no TEMPO signal was observed, indicating the absence of singlet oxygen generation. Therefore, the comprehensive EPR evidence confirms the chemical probe findings, ultimately proving that MP-CD-I only produces O2. •- without producing •OH or 1 O2. These results collectively confirm that MP-CD-I is the sole generator of O2. •- As the sole ROS product, this remarkable selectivity is attributed to the unique electronic structure imposed by cation modification, which restricts excited-state relaxation channels and effectively suppresses alternative energy dissipation pathways. Therefore, the excitation energy is specifically directed to a single photodynamic pathway, ensuring highly controllable and predictable oxidation activity.

[0040] (2) Photothermal performance First, the UV-Vis absorption spectra of MP-CD and MP-CD-I at 638 nm were studied. Solutions of MP-CD and MP-CD-I were prepared with PBS at concentrations of 50, 75, 100, and 125 μg / mL to evaluate the light-harvesting capabilities of the materials. Figure 11 As shown, both MP-CD and MP-CD-I exhibit concentration-dependent absorption characteristics; compared with MP-CD, MP-CD-I shows a significantly higher absorbance at 638 nm, which may be due to the enhanced electron delocalization caused by cation modification.

[0041] Subsequently, the photothermal heating behavior of MP-CD-I was investigated. 1 mL of MP-CD-I aqueous suspension at concentrations of 0, 75, 150, 300, and 450 μg / mL was added to 1.5 mL EP tubes, respectively, and then heated with a power density of 1.5 W / cm². 2 The solution was irradiated with a 638 nm laser for 10 minutes. Simultaneously, 150 μg / mL MP-CD-I was irradiated with the same 638 nm laser at power densities of 0.5, 1.0, and 1.5 W / cm² for 10 minutes each. Temperature changes were monitored using an infrared thermal imaging camera, and thermal images were captured at different time points. The photothermal stability of MP-CD-I was evaluated using a laser-on-off cycle experiment. The procedure involved irradiating 1 mL of a 150 μg / mL MP-CD-I aqueous suspension with a 638 nm laser for 10 minutes, then turning off the laser and allowing it to cool naturally to the initial temperature. This cycle was repeated four times, with continuous recording of temperature changes. 150 μg / mL MP-CD-I was irradiated with the same 638 nm laser at power densities of 0.5, 1.0, and 1.5 W / cm² for 10 minutes each. 2After 10 minutes of illumination, the temperature rise increased with increasing power density. During the light-on-off cycle experiment, the material was allowed to cool naturally to the initial temperature after each 10-minute illumination. This process was repeated several times, and the temperature rise curve remained basically consistent, indicating that the material has good photothermal cycle stability.

[0042] As shown in Figure 9(d), the MP-CD-I dispersion exhibited a significant concentration-dependent temperature increase under laser irradiation (0–450 μg / mL), with the thermal response intensity increasing proportionally with increasing concentration. In contrast, pure water showed almost no heat generation under the same conditions. Figure 9(e) shows that the photothermal properties were also highly dependent on the laser power density, with temperature increases ranging from 0.5–1.5 W / cm². 2 The proportions remained consistent across the range. This trend was confirmed by infrared thermography of MP-CD-I dispersions at different concentrations (0, 75, 150, 300, and 450 μg / mL) under 638 nm laser irradiation for different durations, as shown in Figure 9(f). Notably, cation modification not only promoted electrostatic bacterial targeting but also appeared to promote non-radiative decay processes, thereby contributing to the excellent photothermal conversion efficiency of MP-CD-I. Figure 9(g) evaluated the photothermal stability of MP-CD-I through continuous on / off irradiation cycles. The material maintained a stable temperature profile without significant degradation, indicating its excellent photostability and recyclability. Furthermore, the single-cycle heating-cooling curves in Figure 9(h) depicted the rapid photothermal conversion kinetics, followed by passive cooling behavior, highlighting the material's responsiveness to laser activation.

[0043] Example 4: Selective antibacterial activity against Staphylococcus aureus (1) Staphylococcus aureus ( S. aureus As a representative of Gram-positive bacteria, the antibacterial properties of MP-CD-I were tested. The experiment consisted of six concentrations: 100 μL of bacterial suspension containing Staphylococcus aureus (colony count 10⁻⁶) was used for each concentration. 8 CFUmL -1 Add 0, 30, 60, 90, 120, and 150 μL of 1 mg / mL MP-CD-I suspension (prepared in PBS) to 2 mL EP tubes, then add sterile neutral PBS to each EP tube to a final volume of 1 mL. The MP-CD-I suspension concentrations are 0 (pure PBS), 30, 60, 90, 120, and 150 μg / mL. The sample is then analyzed at 638 nm and 1.5 W·cm⁻¹. -2 After 10 minutes of laser irradiation, 80 μL of the diluted bacterial suspension was evenly spread onto a solid culture medium plate. The plates were incubated at 37°C for 24 hours. Bacterial growth morphology was observed, and relative bacterial activity was assessed by counting colonies and comparing them with a 0 μg / mL control group.

[0044] As shown in Figure 12(a), MP-CD-I exhibited a strong, concentration-dependent bactericidal effect against *S. aureus*. Quantitative results... Figure 12 (b) shows that at relatively low concentrations of 30 and 60 μg / mL, MP-CD-I inhibited bacterial proliferation, reducing colony formation by approximately 10% and 30%, respectively, compared to the PBS control group (0 μg / mL). Increasing the concentration to 90 μg / mL further reduced the survival rate to approximately 40%, while at 120 μg / mL, only a small number of colonies remained, corresponding to a survival rate of approximately 20%. Notably, at 150 μg / mL, MP-CD-I achieved near-complete clearance of *S. aureus*, with the survival rate plummeting to 0.93 ± 0.138%, demonstrating its remarkable efficacy against this pathogen.

[0045] (2) MP-CD and MP-CD-I with Staphylococcus aureus (100 µL, 1×10⁻⁶) 8 CFU / mL) were co-cultured at a concentration of 150 µg / mL and maintained at 37°C. The experiment was divided into a light treatment group (exposed to a 638 nm laser for 10 minutes at a power density of 1.5 W / cm²). 2 The bacterial suspensions were divided into a light-treated group and a non-light-treated group. The light-treated groups included PBS + laser, MP-CD + laser, and MP-CD-I + laser. The non-light-treated groups included PBS, MP-CD, and MP-CD-I. All groups were cultured for 24 hours. After serial dilutions, 80 μL of the diluted bacterial suspension was inoculated onto solid culture media. The antibacterial activity of MP-CD and MP-CD-I was assessed using the plate count method. All experiments were repeated three times.

[0046] Figure 12(c) and Figure 12(d) shows that MP-CD exhibits only moderate activity against Staphylococcus aureus, with an antibacterial rate of only 63.89 ± 1.963% under laser irradiation. This moderate effect can be attributed to the mild photodynamic therapy (PDT) and photothermal therapy (PTT) contribution of the carbon dot-porphyrin hybrid framework, which lacks the enhanced electrostatic interactions provided by cationic modification. In contrast, MP-CD-I achieved near-complete eradication of Staphylococcus aureus (survival rate <1%) under the same irradiation conditions. Notably, neither MP-CD nor MP-CD-I showed significant antibacterial activity in the absence of light, confirming that the bactericidal effect is strictly photosensitive and that the cationic framework primarily acts as a targeting and photophysical modulator, rather than a traditional antibacterial agent. These control experiments collectively demonstrate that the significant efficacy of MP-CD-I stems from the synergistic effect between cationic targeting and phototriggered ROS generation.

[0047] (3) With Escherichia coli ( E. coli As a representative of Gram-negative bacteria, the antibacterial properties of MP-CD-I were tested. The experiment consisted of six concentrations: 100 μL of bacterial suspension containing *E. coli* (colony count 10⁻⁶) was used for each concentration. 8 CFU mL -1 Add 0, 100, 200, 300, 400, and 500 μL of 1 mg / mL MP-CD-I suspension (prepared in PBS) to each EP tube, followed by the addition of sterile neutral PBS to each tube until a final volume of 1 mL is reached. The MP-CD-I suspension concentrations are 0 (pure PBS), 100, 200, 300, 400, and 500 μg / mL. The suspension is then analyzed at 638 nm and 1.5 W·cm⁻¹. -2 After 10 minutes of laser irradiation, 80 μL of the diluted bacterial suspension was evenly spread onto a solid culture medium plate. The plates were incubated at 37°C for 24 hours. Bacterial growth morphology was observed, and relative bacterial activity was assessed by counting colonies and comparing them with a 0 μg / mL control group.

[0048] like Figure 13 As shown in (a), MP-CD-I showed significantly weaker activity against Escherichia coli, exhibiting almost no inactivation ability even at concentrations as high as 300 μg / mL. Figure 13Quantitative analysis in (b) further confirmed this significant specificity. Significant antibacterial activity against *E. coli* was only observed at 400 μg / mL, at which point the survival rate remained at 48.3 ± 2.178%. Even at the highest tested concentration of 500 μg / mL, the survival rate of *E. coli* was still 3.83 ± 0.941%, a concentration (500 μg / mL) more than three times the concentration required to eradicate *Staphylococcus aureus* (150 μg / mL). This significant difference in sensitivity highlights the intrinsic insensitivity of Gram-negative bacteria to MP-CD-I-mediated phototherapy, indicating that selectivity against *Staphylococcus aureus* is an inherent characteristic of the MP-CD-I cationic backbone. Furthermore, according to... Figure 13 (c)~ Figure 13 (d) It can be seen that although the toxicity of MP-CD to Escherichia coli is negligible, indicating that MP-CD also exhibits selectivity in bactericidal activity, it is not necessarily true that the selectivity of MP-CD is higher than that of MP-CD-I. This is because MP-CD-I has a significantly higher bactericidal rate against Staphylococcus aureus at low concentrations (≤150 μg / mL) than MP-CD. However, both have weak bactericidal effects against Escherichia coli at the same or similar concentrations. Therefore, MP-CD-I exhibits a more obvious selective anti-Staphylococcus aureus activity. The selectivity of MP-CD-I originates from two aspects: the conjugated connection between carbon quantum dots and porphyrin, and the quaternized pyridinium structure jointly regulate excited-state relaxation and charge transfer.

[0049] Example 5: Bacterial Morphology and Biofilm Experiments (1) The SYTO-9 and PI dual-fluorescence staining method was used to distinguish between live and dead bacteria. SYTO-9 can penetrate the cell membrane of all bacteria (regardless of membrane integrity), causing them to exhibit green fluorescence; while PI can only penetrate bacteria with damaged membranes, causing them to exhibit red fluorescence, and at the same time weakening the green signal of SYTO-9. The experimental groups were the same as in Example 4 (2), divided into 6 groups, at a power density of 1.5 W / cm². 2 The bacteria were irradiated with a 638 nm red laser for 10 minutes. Then, 100 μL of bacterial solution was taken from each group. Under dark conditions at 37°C, 20 μL of a 1.5 × 10⁻⁶ solution was added. -3 20 μL of SYTO-9 (mol / L) and PI (at the same concentration) were used. After staining for 15 minutes, excess dye was removed by centrifugation with PBS buffer. The bacteria were then resuspended in 50 μL of PBS and placed on a glass slide. Finally, images of Escherichia coli and Staphylococcus aureus were acquired using an inverted fluorescence microscope. Each experimental procedure was repeated three times to ensure the reliability of the results.

[0050] Figures 14(a) and 14(b) show the live / dead fluorescence staining: In the PBS group, bacterial cells were predominantly stained green (SYTO 9, indicating live cells with intact membranes), while red fluorescence (propidium iodide, PI, indicating dead cells with damaged membranes) was negligible, reflecting strong viability. The MP-CD and MP-CD-I groups (150 μg / mL) without laser irradiation showed no significant difference from the control group, confirming that the dark toxicity of these materials was negligible. In stark contrast, 638 nm laser irradiation triggered a fluorescence transition from green-dominant to red-dominant, reflecting gradual membrane damage and impaired cell viability. Notably, unlike the MP-CD+ laser group, which showed a uniform distribution of green and red fluorescence (indicating moderate and incomplete bacterial killing), the MP-CD-I+ laser group showed predominantly red staining, confirming almost complete bacterial clearance. This visual trend perfectly matched the quantitative colony count results, validating the powerful bactericidal effect of MP-CD-I under light activation.

[0051] (2) The experimental grouping was the same as in Example 4(2), divided into 6 groups. Each group solution was added to 2.5 wt% glutaraldehyde solution and fixed at 4℃ for 24 h. After that, it was washed 3 times with PBS, embedded and blocked with agar. The bacteria were treated with ethanol solutions of 30 wt%, 50 wt%, 70 wt%, 90 wt%, 95 wt% and 100 wt% concentrations for 10 min in sequence to dehydrate them. Then they were treated with acetone for 3 h for gradient permeation embedding. Finally, the bacteria were negatively stained, fixed on nickel grid and observed by transmission electron microscopy. The transmission electron microscopy of Figures 14(c) and 14(d) showed that the Staphylococcus aureus cells in the PBS group exhibited the characteristics of healthy cocci, with intact and smooth cell membranes, uniform electron-dense plastids and well-organized intracellular contents with obvious compartmentalization. In contrast, the bacteria exposed to MP-CD-I under laser irradiation showed severe morphological deformation, indicating catastrophic damage. Obvious cell membrane contraction, wrinkling, and local rupture can be clearly observed, accompanied by leakage of cytoplasmic contents into the extracellular space. In more severe cases, some cells exhibit vacuolation, cytoplasmic disintegration, and loss of their typical spherical morphology, indicating that intracellular disintegration goes beyond simple membrane damage.

[0052] (3) Biofilm detection was performed using the crystal violet method. Staphylococcus aureus and Escherichia coli were used for modeling: 150 μL of liquid culture medium and 50 μL of bacterial suspension were added to each well of a 96-well plate, and the plates were incubated for 72 hours. The experiment was divided into a control group (PBS group), an MP-CD-I group, and an MP-CD-I + laser group. 50 μL of MP-CD-I was added to each group containing MP-CD-I; the laser group used a 638 nm, 1.5 W / cm² laser. 2 Laser irradiation for 10 min. The above groups were added to the incubated bacterial culture and incubated for another 5 hours. After incubation, the bacteria were stained with crystal violet (CV): washed with PBS, fixed with 100 μL of methanol for 30 min, washed with PBS, and finally incubated with 50 μL of 0.1% crystal violet for 20 min. After incubation, washed with PBS until clear, added 100 μL of glacial acetic acid, and incubated for 30 min. The supernatant was then transferred to a blank plate to measure the OD value (490 nm). Biofilm ratio = OD value of each treatment group / OD value of the PBS control group × 100%.

[0053] As shown in Figure 15(a), CV staining revealed a significant reduction in *S. aureus* biofilm biomass after treatment with MP-CD-I (150 μg / mL) combined with 638 nm laser irradiation. In the absence of light, MP-CD-I had almost no interference with bacterial adhesion and biofilm formation, with comparable absorbance values ​​between the PBS and MP-CD-I groups. However, after laser activation, the biomass of *S. aureus* biofilm in the MP-CD-I + laser group decreased sharply, by approximately 80% compared to the PBS group. This quantitatively confirmed its strong photokilling efficiency against bacteria embedded in the extracellular polymeric matrix (EPS). Figure 15(b) shows that under the same treatment conditions, the biomass of *E. coli* biofilm remained essentially unchanged, with absorbance values ​​comparable to the PBS control group, highlighting the significant selectivity of MP-CD-I for Gram-positive biofilms.

[0054] Confocal laser scanning microscopy (CLSM) was further employed to obtain high-resolution, three-dimensional information on the structural integrity and viability distribution of residual biofilms. CLSM images in Figures 15(c)–15(e) show that in both the PBS and MP-CD-I groups, *Staphylococcus aureus* and *Escherichia coli* exhibited dense, continuous, and highly fluorescent biofilm matrices, indicating minimal biofilm damage in the absence of laser irradiation. In contrast, under 638 nm laser irradiation, the MP-CD-I + laser group showed significant degradation of the *Staphylococcus aureus* biofilm structure; three-dimensional reconstruction revealed an almost bare basal layer with only a few punctate fluorescent residues. Conversely, the *E. coli* biofilm remained largely intact under the same laser irradiation, exhibiting a dense and continuous structure comparable to the *E. coli* group. CLSM observations clearly confirm that MP-CD-I had minimal impact on *E. coli* biofilms while effectively removing them. Quantitative analysis, including mean fluorescence intensity (MFI) analysis, confirmed these visual findings. These results indicate that when MP-CD-I is activated by laser light, it can effectively disrupt and eradicate established *S. aureus* biofilms, while showing almost no activity against *E. coli* biofilms. This selective antimicrobial biofilm efficacy can be attributed to the same mechanism as selective bactericidal activity: the cationic framework electrostatically targets the *S. aureus* surface, while the restricted O2... •- It produces (moderate oxidative strength) antioxidants that can effectively overwhelm the weak antioxidant defenses of Gram-positive bacteria, but can be easily neutralized by the strong protective mechanisms of Gram-negative species. It can selectively disrupt *S. aureus* biofilms without damaging the symbiotic *E. coli* population, making MP-CD-I a promising precision medicine candidate for combating biofilm-associated infections.

[0055] Example 6: Biocompatibility Experiment (1) Cell hemolysis experiment: Fresh blood was collected from female KM mice (purchased from Jinan Pengyue Experimental Animal Breeding Co., Ltd.). Red blood cells were harvested after centrifugation at 10,000 rpm for 10 minutes and then washed three times with PBS. The suspension containing 4% (w / w) red blood cells was mixed with MP-CD-I at a volume ratio of 1:9. After incubation at 37°C for 3 hours, the mixture was centrifuged at 10,000 rpm for 10 minutes. 100 µL of supernatant from each group was transferred to a 96-well plate. The absorbance was measured at 570 nm using a microplate reader, with distilled water as a positive control and PBS as a negative control. .

[0056] like Figure 16(a) shows that the hemolysis rate was 0.16±0.20% to 1.58±0.10% in the range of 50 to 400 μg / mL, all of which were less than 5%.

[0057] (2) Cytotoxicity assay: The viability of NIH / 3T3 mouse embryonic fibroblasts (from the Cell Bank of the Chinese Academy of Sciences) was detected using the MTT assay. After digestion, centrifugation, and counting of NIH / 3T3 cells in logarithmic growth phase, they were seeded into 96-well plates with 100 μL of cell suspension added to each well. Excessive evaporation was prevented by adding 200 μL of PBS solution to the surrounding replicates. After 24 hours of incubation, drug solutions were added according to the grouping and concentration gradient of the in vitro antibacterial assay, and the plates were incubated for another 24 hours with the control group. Subsequently, MTT solution (4 mg / mL) was added to each well, and the 96-well plates were incubated for another 4 hours. After 4 hours of incubation, the supernatant was removed, and 150 μL of DMSO was added. After shaking on a shaker for 10 minutes, the absorbance of the 96-well plates was measured at 570 nm using an enzyme-linked immunosorbent assay (ELISA) reader. Each experiment was repeated three times. Figure 16 (b) shows that, within the range of 50–400 μg / mL, the cell viability of NIH-3T3 mouse embryonic fibroblasts after co-incubation with MP-CD-I for 24 h was still higher than 80%, even at a concentration of 400 μg / mL.

[0058] Example 7: Infected Wound Experiment Wound model was established using 5-week-old female KM mice weighing approximately 25g (purchased from Jinan Pengyue Experimental Animal Breeding Co., Ltd.). Mice were randomly divided into 5 groups: PBS group (I), MP-CD group (II), MP-CD-I group (III), MP-CD+laser group (IV), and MP-CD-I+laser group (V), with three mice in each group. Before formal infection, the weight of each group of mice was measured, and all mice were anesthetized. The hair on their backs was shaved, and the wounds were disinfected with 75wt% ethanol (volume fraction) to create a wound with a radius of approximately 5mm. Staphylococcus aureus (1×10⁻⁶) was added to the wound. 6 Mice were infected with CFU / mL and divided into groups. After 24 hours, each group was divided into groups and treated accordingly. The dosage for each group was 50 μL, with MP-CD-I and MP-CD concentrations of 150 μg / mL, and laser irradiation power of 1.5 W cm⁻¹. -2The irradiation time was 10 min. Changes in the back wounds of mice were recorded on days 1, 3, 5, 7, and 9, and the mice's weight was monitored daily. The weight changes and back wound area were plotted. On day 9, mice were anesthetized, and blood was collected from the eyeballs. After blood collection, the mice were euthanized, and the back wounds and major organ tissues (heart, liver, spleen, lungs, and kidneys) were fixed with 10% formalin. Then, H&E staining and Masson's trichrome staining were performed. Two mL of blood was collected from each group for complete blood count analysis.

[0059] As shown in Figure 17(a), clear signs of acute infection were present on day 0, namely purulent discharge, local redness and swelling, and significant swelling at the wound edges, clearly indicating that the effective establishment of the infection focus had been tested. As shown in Figure 17(b), the wound area gradually decreased over time in all groups; however, the closure rate varied greatly among different treatment regimens. Quantitative analysis showed that the MP-CD-I + laser group achieved the most significant healing rate, reaching 98.8 ± 0.225% on day 9, significantly higher than the other four groups (MP-CD + laser group: 91.81 ± 0.204%, MP-CD-I alone: ​​86.82 ± 0.353%, MP-CD alone: ​​72.90 ± 0.484%, PBS control group: 70.34 ± 0.881%). Meanwhile, the body weight measurements in Figure 17(c) showed a gradual and steady increase in all groups, comparable to the PBS group, indicating that MP-CD-I treatment did not cause systemic toxicity or impair normal physiological growth during treatment. The quality of tissue regeneration was systematically assessed using H&E and Masson trichrome staining. Figure 17 The image in (d) shows that the MP-CD-I + laser group exhibited significantly accelerated wound contraction compared to the PBS control group. By day 9, the treatment group showed almost complete wound closure with smooth epidermal coverage and re-epithelialization, while the control group's wounds remained open with obvious crusting. This stark visual contrast clearly highlights the treatment's advantages.

[0060] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A selectively bactericidal cationic carbon quantum dot porphyrin porous organic polymer, characterized in that, A porous polymer is formed by Knoevenagel condensation using carbon quantum dots with several aldehyde groups and porphyrins with methylpyridine rings as structural units. The pyridine nitrogen atom in the porphyrin undergoes an N-alkylation reaction with an alkyl iodide to form an N-alkylpyridinium cation, with the iodide ion acting as the counterion. The porphyrin with the methylpyridine ring is tetrakis(6-methylpyridin-3-yl)porphyrin, and the alkyl iodide is iodomethane. The carbon quantum dots with several aldehyde groups are prepared by the following method: Glutaraldehyde and anhydrous ethanol were added to a high-pressure vessel and heated. After cooling, the resulting solid was dispersed in acetone and chloroform in sequence and centrifuged to remove high molecular weight carbon aggregates. Carbon quantum dots with several aldehyde groups were obtained by vacuum distillation, denoted as CDs. The mass ratio of CDs to tetra(6-methylpyridin-3-yl)porphyrin is 3:

2.

2. The cationic carbon quantum dot porphyrin porous organic polymer according to claim 1, characterized in that, The polymer has a hierarchical pore structure consisting of micropores and mesopores.

3. The method for preparing the cationic carbon quantum dot porphyrin porous organic polymer according to claim 1 or 2, characterized in that, Includes the following steps: (1) Add glutaraldehyde and anhydrous ethanol into a high-pressure container, heat and cool, disperse the resulting solid in acetone and chloroform in sequence and centrifuge to remove high molecular weight carbon aggregates, and distill under reduced pressure to obtain carbon quantum dots with several aldehyde groups, denoted as CDs; (2) Mix CDs and tetra(6-methylpyridin-3-yl)porphyrin, add 1,4-dioxane and mesitylene, stir thoroughly, add trifluoroacetic acid for solvothermal reaction, cool to room temperature after the reaction is completed, filter to separate the solid product, wash, and the carbon quantum dot porphyrin porous organic polymer obtained is denoted as MP-CD; (3) Disperse MP-CD in acetone, add excess iodomethane, heat and stir to carry out the reaction, filter, wash and dry to obtain selectively bactericidal cationic carbon quantum dot porphyrin porous organic polymer.

4. The preparation method according to claim 3, characterized in that, In step (1), the volume ratio of glutaraldehyde to anhydrous ethanol is 1:2; the heating treatment temperature is 150℃ and the time is 2h.

5. The preparation method according to claim 3, characterized in that, In step (2), the mass ratio of CDs to tetra(6-methylpyridin-3-yl)porphyrin is 3:2; the volume ratio of 1,4-dioxane, mesitylene and trifluoroacetic acid is 10:10:

3.

6. The preparation method according to claim 3, characterized in that, In step (2), the temperature of the solvothermal reaction is 180°C and the time is 72h; the washing includes washing with N,N-dimethylformamide, methanol, dichloromethane and dimethyl sulfoxide in sequence until the filtrate is clear.

7. The preparation method according to claim 3, characterized in that, In step (3), the ratio of MP-CD to iodomethane is 100 mg: 1~3 mL; the heating and stirring temperature is 40℃ and the time is 24 h.

8. The use of the cationic carbon quantum dot porphyrin porous organic polymer according to claim 1 or 2 in the preparation of selectively bactericidal antibacterial drugs.

9. The application according to claim 8, characterized in that, The selective sterilization refers to the killing of Gram-positive bacteria; the Gram-positive bacteria is Staphylococcus aureus.

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