Study On Antifouling Surface Using Synergistic Effect Of Surface Topology And Biological Modification

With the vigorous development of global shipping industry and the increased attention on environmental protection,technologies which relates to green ship should be emphasized.The bio-fouling effect brought by marine organisms is a main reason that affects the performance and life span of ships.Traditional anti-fouling coatings have negative impacts on the marine environment and thus many researchers focus on the non-toxic anti-fouling method.In this paper,due to the fact that surface microstructure can reduce the surface energy of materials,micro-topological structure was designed and processed on 304 stainless steel surface to reduce the surface energy.At the same time,the biologic peptide with two sulfur bonds was added to react with the topological surface to form the organic surface.This article analyzed these surfaces,including surface character,the size of the structure,as well as anti-bacterial abilities of these designed surfaces.In this paper,the topology structure of the surface was designed based on the theory of attachment points and roughness index.The width of two type of structure was divided into three types and 6 kinds of surfaces at all.The above-mentioned surface structure was machined by Reactive Ion Etching(RIE)on the surface of 304 stainless steel and then the parameters and dimensions of the surface were measured by the Laser Confocal Scanning Microscope.As a result,the surface roughness of the material increased compared to the original surface,about 0.4?m.The processing error before and after are both less than 10% and the depth of the structure is about 0.8?m.In the bio-peptide modification process,the peptide used in the experiment was modified by adding two disulfide bond to improve the reaction ability between biopeptide and the metal surface.Its sequence number is NCLNPNTASACMHV(C-C disulfide).The surface reaction of biologically modified peptides was verified by Xray photoelectron spectroscopy(XPS)and XPS results showed that element S significantly increased after reaction.Besides,element N can prove that the peptide did react with the metal material.Quantitative analysis of XPS showed that the surface of vertically arranged structure was more likely to bind to the bio-peptide than the liner arranged structure.The change of surface energy on the 304 stainless steel surface was reflected by testing the contact angle(CA)with water,the CA was measured by the contact angle measuring instrument.The contact angle of the original surface was 74.90±0.86 °.After the bio-peptide treatment,the contact angle of the 304 stainless steel surface increased to 85.00±2.02° and the surface contact angle increased to 98.88±1.60° after the surface structure treatment.The contact angle with surface structure as well as bio-peptide treatment reached up to 113.62±2.32 °,which indicates that the effect of biological peptide treatment and surface structuring on 304 stainless steel surfaces can be superimposed.In addition,different types of grooves have different effects on surface energy.The smaller the width of surface groove is,the larger the contact angle of 304 stainless steel surface,and the contact angle of the liner arranged structure is larger than the contact angle of the vertically arranged with the same width.Bacterial biofilm test and anti-fouling performance test showed that the surface structure has a certain effect on inhibiting biological fouling.Compared to the inhibitory effect to formation of bacterial biofilm brought by structure surface without bio-peptides treatment,the surfaces with bio-peptides treatment had better inhibitory effects.The smaller the groove width is,the greater the inhibition is and the inhibition effect to E.coli is greater than the S.aureus.Anti-fouling test showed that the inhibition of surface structure on seaweed was obvious and the inhibition rate was further improved after bio-peptide treatment.Meanwhile,the width of surface structure would affect the inhibition rate of algae on the surface,and the smaller the width is,the higher the inhibition rate to algae,and vice versa.Compared with the original 304 stainless steel,the surface with structure and bio-peptide treatment have lower surface energy,which can inhibit the formation of bacterial biofilm as well as adhesion of algae.It provides a new idea for the development of environmental anti-fouling technology.