A Study On Preparation Of Hydrophobic ZnO Thin Films And Anti-biofilm Performance

At present,the preparation,device development and the theoretical research of physicochemical property of nano-ZnO thin film materials have been investigated extensively,and larger progress has been achieved.As we know,the bacteria can adhere to solid surfaces and form a slippery biofilm in appropriate environments.Biofilm would result in equipment corrosion and food contamination,leading to huge economic losses.As a kind of antibacterial coating,ZnO film has been used to improve its antibacterial properties by ion doping,but has little been researched on inhibiting biofilm adhesion.In this paper,based on reducing the biofilm adhesion on the material surface,the preparation of ZnO thin films on the different base material surfaces and their performances have been studied,such as hydrophobic property,inhibit biofilm adhesion and antibacterial properties,and so on.Hydrophobic or superhydrophobic surface material have been obtained through the construction of micro-nanostructure and surface modification.Shewanella putrefaciens has been used as the indicator bacteria.The anti-biofilm properties of ZnO films have been affected due to the different micro-nanostructure and hydrophobic property.(1)Preparation and anti-biofilm properties of ZnO film by sol-gel methodIn this work,the Porous Anodic Alumina(PAA)films with different microstructures were prepared by two-step anodic oxidation firstly,and then the ZnO films were prepared by sol-gel method based on the different microstructural PAA.After modified by 1%Si69 ethanol solution,the ZnO films were translated to hydrophobic from hydrophilic due to the surface hydroxyl group on the ZnO particles.Among them,ZnO thin films with Hexagonal honeycomb frame structure have obtained the near-superhydrophobic properties.The results of microbial experiments showed that,the near-superhydrophobic properties reduced the number of bacteria adhesion in the initial stages of biofilm formation effectively.Moreover,due to its surface with more nano-ZnO particles,it exhibits stronger antibacterial activity against Shewanella putrefaciens.(2)Preparation and anti-biofilm properties of ZnO film by hydrothermal methodZnO films were prepared by hydrothermal method on the surface of stainless steel substrate.Some characteristic of ZnO films were affected by the pH value of reaction system and the amount of Ag doped,such as microscopic morphology structure,hydrophobic or hydrophilic properties,anti-biofilm adhesion and antibacterial properties.The length of Six prismatic ZnO nanorods were to be increased with pH value rises.When the pH value was 11.5,the ZnO nanorods gathered into a bundle at the top every several nanorods.Furthermore,the space between ZnO nanorod bundles was enlarged with the amount of Ag doped and the ZnO films had a more uniform micronano-structure.After modified by stearic acid,the surfaces ZnO nanorods were combined with hydrophobic groups and the spaces between ZnO nanorod bundles were filled with more air.The synergy between them caused water droplets alienating from the surface of ZnO film and led to lotus effect more powerfully.The adherence of Shewanella putrefaciens were effectively reduced due to the super-hydrophobic properties of ZnO films.Furthermore,the zinc ion and the silver ion eluted from the surface of Ag doped ZnO films were combined with the active protease in bacteria and made them out of activity,which led to bacteria cells damage until death.This illustrated there were synergistic antibacterial effects between the zinc ion and the silver ion.(3)Preparation and anti-biofilm properties of ZnO film by cathodic electrodeposition methodZnO films were prepared by cathodic electrodeposition method on the surface of titanium substrate.Microscopic morphology structure and hydrophobic or hydrophilic properties of ZnO films were affected by the difference of reaction system,reaction time and temperature.Meanwhile,anti-biofilm adhesion and antibacterial properties were analyzed.The hydrophobic properties of ZnO film were influenced directly its microstructure.In KCl system,with the extension of electrodeposition time,the microstructure of ZnO deposited on titanium substrate was transformed from six prismatic columns to bulks until to primrose auricular structure on the bulk surfaces.In CH₃OONH₄ system,with the increase of electrodeposition temperature,the microstructure of ZnO deposited on titanium substrate was transformed from tracery nano-walls to mixed structure of tracery nano-walls and nanorods until to nanorod structure.The results indicated that ZnO films with primrose auricular and tracery nano-walls micro-nanostructure gained hydrophobicity or super-hydrophobicity more easily.The adherence were effectively reduced due to the super-hydrophobic properties of ZnO films,and the ZnO films with smaller nanoscale(primrose auricular and tracery nano-wall)structure showed outstanding antimicrobial properties.