Molecular Dynamics Study On Bioadsorption Behavior Of Marine Fouling In The View Of Peptide Conformation

Biofouling is one of the main sources of corrosion in marine equipment.It is generally inhibited by applying antifouling coatings to the equipment surface.However,the adsorption mechanism of fouling organisms on the material surface is complex and diverse.The adsorption behavior directly affects the design strategy of antifouling coatings.In order to accurately predict the adsorption behavior of fouling organisms on the surface of marine equipment,this paper studies the internal mechanism of marine fouling bioabsorption from the perspective of peptide conformation.In this paper,the intrinsic mechanism of marine fouling biosorption was investigated from the perspective of peptide conformation.Using the molecular dynamics simulation,taking barnacle as the research object which is the widely existing fouling organism,the following studies were carried out around the peptides which are composed of frequently occurring amino acid residues(Thr,Ala,Gly,Cys)in adhesion proteins.This thesis is divided into the following two parts:(1)Adsorption strength and adsorption behavior of peptide molecules on epoxy resin surface.For the commonly used commercial coating material epoxy resin,the peptide molecule-epoxy resin-water solution system was simulated by molecular dynamics with the developed epoxy resin force field parameters.The adsorption sites and adsorption mechanisms were determined according to the dynamic adsorption trajectory of peptide on the epoxy resin surface.The "four-box" method was used to calculate the adsorption energy of each peptide on the epoxy resin surface.The results show that the adsorption strength of different peptide molecules is positively correlated with the adsorption site.The accuracy of calculation results of peptide molecular conformation was improved by self-developed identification and statistical methods of PPII helix.According to the correlation analysis of the adsorption energy,adsorption site and secondary structure conformation ratio of peptide molecules on the epoxy resin surface,a method for judging the adsorption behavior of the peptide molecule on the epoxy resin surface by the peptide conformation was proposed.By simulating the adsorption behavior of control peptides on the epoxy resin surface,the dependence of adsorption site and peptide conformation on adsorption strength was further demonstrated.(2)Prediction and verification of adsorption behavior on epoxy resin surface based on analysis of peptide conformation under environmental influenceIn order to analyze the influence of environmental factors on the fouling biosorption behavior,molecular dynamics simulations were performed on the correlation between different seawater parameters such as ionic strength,ionic species,pH,and temperature,and peptide conformations.And the adsorption behavior on the epoxy resin surface was predicted based on the correlation between the adsorption strength and the peptide conformation given above.Finally,by simulating the adsorption strength of peptide molecules on the epoxy resin surface at different temperatures,the intrinsic relationship between environmental factors(temperature)-peptide conformation-adsorption strength was verified,which was consistent with the predicted conclusion.In conclusion,this paper presents a simulation method to study the adsorption mechanism of biofouling which was interpreted from the atomic scale.Different from previous studies on the adsorption mechanism of fouling organisms,this thesis analyzes the adsorption mechanism of marine fouling organisms from the perspective of peptide conformation.The results show that the conformations of peptides are decisive for its adsorption behavior on the epoxy resin surface.This method can be used to evaluate the adsorption behavior of peptide molecules on the surface of substrate materials,and can also predict the adsorption behavior of fouling organisms in different marine environments.This provides a clear judgment basis for the selection of antifouling coatings under different operating environments.