Controllable Synthesis Of Copper Nanoparticles Decorated Different Fullerenol Composite With Multi-mophorlogy Towards Photodynamic Antibacterial Application

In recent years,bacterial infection has posed a severe challenge to public healthcare,imposing a heavy economic burden on patients.Though various antimicrobial agents like antibiotics have been developed to deal with this threat,the increasing resistance of bacteria to antibiotics has become a serious limitation due to their extensive use.Thus,it is rather urgent to develop new antibacterial materials or therapies to solve these problems.As a milder and safer treatment for bacteria inhibition,photodynamic therapy（PDT）has received extensive attention.Among numerous photosensitizers（PS）,fullerene possesses great potential due to its special conjugated structure and satisfactory biocompatibility.Under laser irradiation,fullerene continuously produces radical oxygen species（ROS）through energy transition and electron transfer to inhibit the growth of bacteria.At the same time,copper nanoparticles（CuNPs）have good synergistic antibacterial effects due to their high redox potential,low cost,and broad-spectrum bactericidal effect.Based on this,different CuNPs@fullerenol composites with multi-mophorlogy were prepared using liquid-liquid interface precipitation（LLIP）and photochemical reduction methods to enhance their antibacterial properties.The main researches are as follows:（1）Fullerenol was successfully prepared by hydroxylation reaction,and its water solubility was verified.The morphology of fullerenol controlled by the LLIP method,in which the mixed solvents were dimethylformamide（DMF）/methanol（3/1,v/v）,the most regular and smallest spherical clusters（about 150 nm）could be obtained.Then,CuNPs could be anchored on the surface of spherical and irregular fullerenol by photochemical reduction method so as to synthesize two new composite materials.（2）Compared with single materials（CuNPs,fullerenol）,the above two composite materials have stronger inhibitory activity（with a bacteriostatic rate up to 90%）against S.aureus（Gram-positive bacteria）and E.coli（Gram-negative bacteria）.Through the investigation of antibacterial mechanism,it was found that composite materials could generate a large amount of singlet oxygen（¹O₂）and superoxide anion（·O₂^-）for antibacteria under laser irradiation.CuNPs could play a synergistic antibacterial role by releasing Cu²⁺.The copper nanoparticles/spherical fullerenol has a stronger ability to generate ¹O₂ than copper nanoparticles/irregular fullerenol,and a better promoting effect on wound healing as well.（3）In order to investigate the effect of morphology on antibacterial properties of the composite,flake and acicular-shaped fullerenol were further prepared.The antibacterial properties of composite materials with different morphologies were tested under dark and laser-irradiation conditions,respectively.It was found that the stability and sharpness of composite materials under dark condition were the key factors affecting their antibacterial properties.The composite material with more active sites with oxygen and less energy required for energy band transitions has a stronger ability to produce ¹O₂ under laser irradiation,resulting better antibacterial performance.