Preparation Of Gold Nanostructure Materials Based Photothermal Agents And Near-infrared Photothermal Antibacterial Applications

The emergence of resistant bacteria caused by the abuse of antibiotics is seriously threatening human health and safety,and the traditional antibiotic antibacterial method is basically ineffective against drug-resistant bacterial infections.The development of the new antibacterial methods which are alternative,safe,high efficient and difficult to produce new antagonistic is an hot topic.Photothermal antibacterial method kills the bacteria through thermal ablation,which relies on the hyperthermia produced by the near-infrared irradiation on the photothermal agents.Because the photothermal antibacterial method is not easy to cause bacteria to develop resistance,it is a new antibacterial technology with good application prospect.The core of photothermal antibacterial method is photothermal agents,the design and preparation of photothermal material with good photothermal conversion performance has become one of the research focuses in the field of photothermal antibacterial.Due to high light stability,easy modification and high photothermal conversion efficiency,gold nanostructured materials are favored in the research of photothermal agents.The design and preparation of photothermal agents based on gold nanostructures provide new opportunities for the biological antibacterial field.In this paper,three kinds of gold-based nano-photothermal agents were designed and applied in the near infrared photothermal bacteria.The main results are as follows:1.Photothermal lysis of pathogenic bacteria by platinum nanodots decorated gold nanorods under near infrared irradiationFirstly,Au nanorods?NRs?with uniform morphology were prepared by gold seed growth method.Then,Au NRs were used as the core,and Pt nanodots were decorated on the surface by chemical reduction method to prepare nanostructured bimetallic Au@Pt NRs photothermal agents.The experimental results show that the Au@Pt NRs prepared from single-crystalline Pt nanodots modified Au NRs not only improve the photothermal conversion efficiency,but also significantly enhance the interaction with bacteria.Au@Pt NRs showed good photothermal bactericidal efficiency for both gram-positive and gram-negative bacteria.In addition,Pt loading and concentration of Au@Pt NRs,laser power density and irradiation time significantly affect photothermal efficiency.The cytotoxicity of Au@Pt NRs is lower than that of Au NRs.Au@Pt NRs is a kind of photothermal material with good biocompatibility and high efficiency,which can be used to kill various pathogens.2.Near-infrared photothermal antibacterial properties of peptide A?_25-35modified gold nanorodsFirstly,Au NRs with uniform morphology were prepared through gold seed growth method,and 11-sulfanylundecanoicacid was modified on the surface through Au-S bonds.Then,11-sulfanylundecanoicacid was activated by EDC/NHS to combine with the hydroxyl of peptide A?_25-35,leading to the synthesis of inorganic biocomposite nanostructured Au@A?_25-355-35 NRs.The experimental results show that Au@A?_25-355-35 NRs have higher photothermal conversion efficiency,better photothermal antibacterial effect and stronger interaction with bacteria than the original Au NRs.Au@A?_25-355-35 NRs exhibited good photothermal bactericidal efficacy against S.aureus.3.Peptide A?_25-35-templated synthesis of gold nanostructured materials and their photothermal antibacterial propertiesFirst,the peptide A?_25-355-35 monomer and fiber were prepared by controlling the incubation time for 0 h and 12 h.Then they were used as templates to prepare nanostructured Au_P00 and Au_P1212 in a single step by chemical reduction method,respectively.The experimental results show that the gold nanostructured material Au₀prepared without template has irregular particle morphology;the gold nanostructured material Au_P00 prepared by the templated method has uniform and regular spherical particles;Au_P1212 possesses a fibrous morphology.The results also show that compared with Au₀ and Au_P0,Au_P1212 has good photothermal conversion efficiency and can photothermal killing of MRSA effectively,so it is an ideal nano-photothermal agent.