Preparation Of Nano-gold Composites By Atmospheric Pressure Microplasma And Their Photothermal Antibacterial Properties

Atmospheric pressure microplasma（APM）technology is widely used in the preparation and surface treatment of polymers and metal materials due to a series of advantages such as high efficiency,convenience,simple equipment,clean and pollution-free.This technology has been used for the connection between ceramics and metals,and can also be applied for the synthesis of nanocomposites.Based on the clinical requirement of skin wound dressings and periodontal membrane repair materials,this thesis employed chlorauric acid（HAu Cl₄）,polyvinyl alcohol（PVA）and hydroxyapatite（HAP）as the raw materials,and three kinds of nanocomposites,including AuNP/PVA,AuNP/HAP and AuNP/HAP/PVA were successfully synthesized by APM technology.The effects of raw material component concentration/content on the structure and properties of nanocomposites were discussed in detail,the interactions between different components in the nanocomposites were analyzed,and their biomedical application potential was preliminary explored.The main conclusions are as follows:（1）During the APM treatment of AuNP/PVA solution,plasma jet reduced Au³⁺to Au⁰,and PVA molecules were connected with AuNPs via the C-O-Au bond,which avoided the aggregation of AuNPs.With the increase of HAu Cl₄ concentration,the particle size and dispersion of AuNPs increased,while the surface pore size,porosity,swelling rate,and plasticity of AuNP/PVA nanocomposites decreased,along with increased tensile strength.After NIR irradiation,the surface temperature of AuNP/PVA nanocomposites increased,thus increasing their antibacterial rates.With the increase of PVA content,the dispersion of AuNPs became better,and the particle size did not change significantly;meanwhile,the surface pore size,porosity and swelling rate of materials reduced sharply,while the tensile strength and plasticity increased.After NIR irradiation,the surface temperature of materials decreased slightly,and their antibacterial rates did not show any obvious changes.Among the prepared materials,2.0 m M AuNP/m-PVA nanocomposite possessed good photothermal antibacterial properties,mechanical properties,and coagulation ability,showing great potential for wound dressing applications.（2）In the UV spectra of AuNP/HAP solution,the transverse LSPR peaks of gold nanoparticles were observed,which indicated the successful preparation of AuNPs by plasma jet.The results of FTIR,XPS and XRD diffraction peaks showed that AuNPs were adsorbed on the surface of rod-like HAP nanoparticles through electrostatic interaction.With the increase of HAu Cl₄ concentration,the particle size of AuNPs increased,the degree of agglomeration increased,the solution temperature increased after NIR irradiation,and the antibacterial rate increased.With the increase of PVA content,the particle size of AuNPs increased,the degree of agglomeration decreased,and the solution temperature increased after NIR irradiation.Particularly,1.0 m M AuNP/m-HAP nanocomposites showed the best antibacterial performance,which is very attractive for anti-bacterial applications.（3）During the APM process,Au³⁺in the AuNP/HAP/PVA solution was reduced to elemental gold by plasma jet.AuNPs were predominantly adsorbed on the surface of HAP nanoparticles by electrostatic interaction,and the remaining ones formed C-O-Au bonds with the-OH bond of PVA.With the increase of HAu Cl₄ concentration,the particle size and aggregation of AuNPs increased.The pore size and porosity of AuNP/HAP/PVA nanocomposites decreased first and then increased,which was consistent with the change of swelling rate and tensile strength;however,the plasticity of materials showed an opposite change.After NIR irradiation,the surface temperature of materials increased,and the antibacterial rate increased.With the increase of HAP content,the particle size and aggregation of AuNPs,the surface pore size and porosity of nanocomposites,and the swelling rate and tensile strength of materials decreased slightly,while the plasticity of materials increased first and then decreased.After NIR irradiation,the surface temperature of materials increased,and the bacteriostatic rate also increased.Especially,1.0 m M AuNP/m-HAP/PVA nanocomposite exhibited high photothermal antibacterial ability and good mechanical properties,which are attractive for periodontal membrane repair.In conclusion,APM provides a convivence and efficient approach for engineering nanocomposites,in which the properties of nanomaterials can be tailored via the optimization of raw materials.The AuNP/PVA,AuNP/HAP and AuNP/HAP/PVA nanocomposites prepared in this thesis possessed good photothermal antibacterial ability,which are very attractive for potential biomedical applications such as wound dressing and periodontal membrane repair.The thesis has 50 figures,5 tables and 136 references...