The Controllable Preparation Of Gold-Based Nanocomposites And Study Of Photothermal Antibacterial Properties

The pathogenic bacterial contaminations and infections are always the great challenge for the healthcare all over the world.Especially,due to the overused of antibiotic drugs,traditional antibiotic drugs show less effectiveness for fighting against the widespread infectious diseases caused by the multidrug-resistant?MDR?bacteria.Finding new long-term solutions for bacterial control and destruction,which could integrate biological methods with novel tools,is absolutely required.With the development of nanotechnology,it became possible to utilize nanomaterials as antimicrobial agents.The combination with Photothermal has emerged as an effective approach to address the problem of pathogenic bacteria infection irrespective of the drug resistant effect.Due to their low cost,high throughput,excellent yield,tunable properties,multifunctionality,controllability,and fast effect they have been recognized as an optimal candidate for defeating even the most challenging pathogens.The use of such nano-materials has shown great potential in many antibacterial applications.Gold nanomaterials have high biocompatibility,excellent photothermal conversion efficiency.The poor selectivity of Gold nanomaterials can be solved by modifying other functional materials.However,most of the gold-based photothermal materials have single function.The exploration of multifunctional photothermal agent is important for antibacterial photothermal lysis.So,three kinds of gold-based functional photothermal agents were designed and prepared to Photothermal bacterial lysis.The main research results are as follows:1.Dual-functional peptide conjugated gold nanorods for the detection and photothermal ablation of pathogenic bacteriaIn the present work,a dual-functional peptide coupling gold nanoconjugate?Au@P937 NRs?was facilely fabricated by conjugating an adhesion peptide?WGLHTSATNLYLHGGGC,P937?with Au nanorods?Au NRs?,of which the peptide P937 was designed by the phage display biopanning technology and showed specific binding affinity to bacteria.After the modification of P937,the longitudinal surface plasmon resonance?LSPR?absorbance peak of the Au@P937 NRs was found to be very sensitive to the variation of bacterial concentration.The Au@P937 NRs exhibited enhanced NIR-based photothermal conversion efficiency.Moreover,the Au@P937 NRs exhibited good biocompatibility.Hence,the Au@P937 NRs could be used as a dual-functional nanoconjugate for the detection and photothermal ablation of bacteria.For the bacterial detection by the Au@P937 NRs,the detection limit could reach 46 cfu mL^-11 for E.coli and 89 cfu mL^-11 for S.aureus,respectively.Both E.coli and S.aureus could be killed completely in 10 min by the Au@P937 NRs under 808nm laser irradiation.This work provided a facile,convenient and effective strategy for detecting and sterilizing bacteria.2.Near-infrared photothermal antibacterial properties of gold nanocomposites functionalized with amyloid polypeptide HIAPP_20-29In the present work,The HIAPP_20-290-29 was self-assembled on the surface of the gold nanorods by the ion and hydrophobic action.The assembled amyloid polypeptide HIAPP_20-290-29 monomer could induce the aggregation of the gold nanorods and was arranged according to the final assembly state of amyloid polypeptide HIAPP_20-290-29 to form Au@HIAPP_20-290-29 nanocomposite.It was found that it showed enhanced photothermal conversion efficiency,excellent bacterial adhesion ability and higher photothermal bactericidal efficiency.3.ReducedGrapheneOxideFunctionalizedwithGoldNanostar Nanocomposites for Synergistically Killing Bacteria through Intrinsic Antimicrobial Activity and Photothermal AblationIn the present work,a 2D reduced graphene oxide supported Au nanostar nanocomposite?rGO/AuNS?was prepared by the seed mediated growth method for synergistically killing multidrug resistant bacteria.Owing to the prickly and sharp-edge nanostructure,the rGO/AuNS displayed superior antibacterial activity probably due to the damaging of the cell walls or membranes.The cell viability of MRSA was as low as 32%when the MRSA were incubated with rGO/AuNS for 180min in the absence of light.The 2D structure of the rGO/AuNS facilitated the strong binding affinity towards bacteria.Upon the 808 nm NIR laser irradiation,significant enhancement in bactericidal efficiency?complete death?was obtained due to the localized hyperthermal effect of rGO/AuNS.Moreover,the RGO/AuNS displayed promising biocompatibility.It indicates that the rGO/AuNS can be an alternative and effective dual functional photothermal agent for synergistically killing the multidrug resistant bacteria.