Study On Preparation And Bactericidal Properties Of Biomimetic Nano-cones

By studying the interaction between bacterial cells and the surface structure of the cicada wing,a purely physical sterilization mechanism was proposed.That is,when the bacterial cells were adsorbed onto the nano-columns on the surface of the cicada wing,the cells suspended and extended within the intercolumn region,and the total area of the bacterial cell membrane increased sharply,along with the stretching of the membrane,which may lead to irreversible membrane rupture and bacterial death,revealing a new field of antibacterial surface research.This paper intends to use a simple and convenient method to prepare the surface of the cicada wing structure,and develop a sterilized,easily desorbable and transplantable surface for implanted medical devices.The template synthesis method is recognized as the most ideal method for synthesizing nano-materials and nano-arrays.Porous anodic alumina(PAA)templates have features such as mono dispersed pore size,high temperature resistance,high strength,low cost,easy availability,and easy shape control,and it is the most widely used templates so far.In this paper,an porous anodized alumina template with an inverted-tapered nano-pore array was successfully prepared by two-step anodic oxidation method.A highly ordered and cicada wing-like nano-cone structure was obtained on the surface of polymethyl methacrylate(PMMA),a medically used polymer,through hot-press forming technology,mold release and alkali etching processes.The bactericidal and bacteriostasis performance of the bionic surface was tested by the means of dead-live staining.The results show that the bionic surface has good bactericidal and bacteriostatic effects.During the preparation of the PAA template by two-step anodic oxidation,the first step of hard anodic oxidation is particularly critical.The setting of the oxidation voltage,the choice of the electrolyte system,and the purity of the selected aluminum sheet will affect the morphology of the final PAA template.However,during the process of preparing the surface of PMMA nano-cone by hot-press molding,the process of alkaline etching is very important.If the lye treatment time is too short,the entire conical structure will appear short and thick,and if it is too long,obvious cone tipping phenomenon will occur.When the alkali etching treatment time is controlled within the range of 80~100 min,an ideal ratio of height to diameter can be obtained.The results of bactericidal performance test shows that the PMMA surface with nano-cone morphology has excellent bactericidal properties,and it can kill most of the adherent bacteria after the inoculation of E.coli within 10 min.The nano-cone structure surface of PMMA with different morphologies have different bactericidal effects.Within a certain degree of order,the more tidy the surface nano-cone structures is,the less obvious of the sterilizing effect.The appropriate structural disorder helps to increase the bactericidal effect of the surface,which may be related to the distribution of bacterial cells on the surface of the nano-cone structure.The contact angle data of the surface of the PMMA imitating cicada wing structure indicates that the surface is a hydrophilic surface,which conforms to the Wenzel model.The hydrophilic property of the surface makes the surface easy to remove the bacterial cells that have been attached to the surface and colonized on its surface,and the bactericidal properties of its structure can be used as an ideal bactericidal surface.