| Pathogenic bacterial infections are one of the main threats to the healthy security of human life,but the long-term use of antibiotics can lead to the emergence of drug-resistance,which can reduce the effectiveness of treatment.Therefore,developing new and efficient treatment strategies that effectively reduce the risk of drug resistance has become one of the major challenges of pathogenic bacteria research.Porphyrins,as an organic photosensitizer with visible near-infrared light absorption properties that are widely present in nature,can be used as a potential photoresponsive antibacterial agent due to their excellent photodynamic properties.However,the poor water solubility of porphyrins leads to weaker antibacterial activity.Bio-metabolizable materials such as porphyrins and black phosphorus are assembled into nano-inhibitors through metal coordination to improve bacterial targeting via electrostatic action,and the combination of photothermal and photodynamic therapies can significantly enhance bacterial inhibition efficiency.Therefore,the thesis summarized the research progress of light-sensing antibacterial agents,I have designed and prepared three new porphyrin-derived antibacterial agents,investigated their structure,composition and performance,and further explored the inhibition efficiency and mechanism against E.coli and S.aureus.The main findings are as follows:（1）Preparation of black phosphorus europium porphyrins and research on its antibacterial properties:In this section,the coordination of black phosphorus（BP）with europium ions(Eu3+)was first investigated and Eu-loaded nanomaterials（BP@Eu）were prepared,followed by black phosphorus europium porphyrins（BP@Eu-TCPP）obtained by coordination of europium with 5,10,15,20-tetrakis（4-carboxyphenyl）porphyrin（TCPP）.Raman,FT-IR and XPS spectras demonstrate the presence of Eu-P and Eu-O coordination bonds.The results showed that the photothermal properties,photothermal stability and inhibition efficiency of BP@Eu-TCPP were significantly higher than those of BP;BP@Eu-TCPP had a stronger affinity for bovine serum protein and lipase with binding constants of 9.26*103and6.52*102respectively.Further studies revealed that BP@Eu-TCPP inhibited the photodynamic properties of TCPP due to the interaction of europium with TCPP;L-arginine could interact with BP@Eu-TCPP to restore the fluorescence and photodynamic properties by forming a TCPP-L-Arg complex.BP@Eu-TCPP can act as a fluorescent turn-on probe for the detection of arginine with a detection limit of4.02μM.The antibacterial mechanism of BP@Eu-TCPP was further investigated and found to be able to alter the original morphology of bacteria,disrupt the integrity of the cell wall and interfere with the uptake of iron ions,pyruvate and the normal redox balance of NADH/NAD+by bacteria.The results show that BP@Eu-TCPP is an L-arginine-activated photodynamic photothermal inhibitor and an L-arginine fluorescence-sensing probe.（2）Preparation of porphyrin covalent organic frameworks encapsulated with gallium black phosphorus and research on their antibacterial properties:In this section,black phosphorus gallium（BP@Ga）was prepared and used as a template to induce 5,10,15,20-tetra（4-aminophenyl）porphyrin（TAPP）and terephthaloyl chloride to form nanoporous materials by amide bonding,followed by copper ion coordination assembly to obtain porous spherical black phosphorus-based porphyrin-copper covalent organic framework materials（BPGa@COF-Cu）.BPGa@COF-Cu has been proven to have high performance in the red light driven generation of single line oxygen and photothermal properties.It was shown that BPGa@COF-Cu acted as a nanoenzyme and catalyzed the production of hydroxyl radicals from hydrogen peroxide.The minimum bactericidal concentration of this compound against E.coli and S.aureus under light was only 1 and 3μg/m L,respectively.BPGa@COF-Cu also disrupt bacterial biofilms by photoactivation.The results show that BPGa@COF-Cu was a synergistic agent for bacterial inhibition that combines photothermal,photodynamic,and chemical dynamic modals.（3）Preparation of metalloporphyrin cellulose and research on its antibacterial properties:In this section,a porphyrin cellulose（CEL-THPP）was prepared using 5,10,15,20-tetra（4-hydrazinyl phenyl）porphyrin（THPP）and dialdehyde cellulose（DAC）by covalent acylhydrazone coupling,with the assembly of Zn ions investigated,resulting in a light-responsive porous metalloporphyrin cellulose（CEL-THPP@Zn）.CEL-THPP@Zn showed a forbidden band width of 1.69e V,a broad absorption band at 400-900 nm and strong fluorescence emission at 662nm.Therefore,the single-linear oxygen production capacity of CEL-THPP@Zn under red light irradiation was superior to that of CEL-THPP.Further studies revealed that CEL-THPP@Zn demonstrated good inhibition of both E.coli and S.aureus and had an adsorption effect on the bacteria.In summary,CEL-THPP@Zn is a surface porous spherical rod-shaped luminescent fibre with a good bacterial adsorption performance,showing a superior broad-spectrum bacterial inhibition in both dark and light conditions. |
