The Application Of Protein-based Superhydrophobic Surface In The Crystallization Of Biological Macromolecules And Food Packaging

Learning from the natural world is an important way to develop new functional materials.In particular,the bionic superhydrophobic material,originated from nature and developed in nature,is widely used in many fields because of their special water resistance characteristics.However,the current superhydrophobic materials suffer from the problems such as complicated preparation process,harsh conditions,biological toxicity and so on,which are difficult to be used in the biological and food industries with high requirements for biosafety.In order to overcome these shortcomings,a new type of protein-based superhydrophobic surface was constructed based on phase-transited lysozyme,which is based on amyloid-like protein assembly.This material not only has the mild and simple synthetic method,but also features excellent material properties.Its biological safety is good due to the inherent characteristics of protein.The material has been used for the crystallization of biological macromolecules and food packaging with good performance,which provides a novel platform for the crystallization of biological macromolecules,and also has a broad application prospects in the food packaging industry.This research work mainly involves the following two aspects:(1)Biomolecule crystallization process on the protein-based superhydrophobic surfaceThe biomolecules crystallization at the interface is an important process in nature.Correct understanding on this process and obtaining the high-quality crystals will be helpful to break through the bottleneck to restrict the development of analytical protein crystallography,which is of great significance to explain well life activities.To solve this problem,this thesis proposes a new protein crystallization pathway that a protein-based superhydrophobic surface provides a biointerface platform that can induce the crystallization of proteins and peptides.Firstly,lysozyme is regarded as a model protein to discuss the effect of superhydrophobic environment on the protein crystallization's process supported by the protein-based surface.The changes of the parameters of the droplet on the surface are in-situ observed and its volume and concentration changes are calculated by establishing simple mathematical model of the protein solution droplet on the surface.It is revealed that the evaporation of a sessile protein buffer droplet on the superhydrophobic biointerface is proceeding in a mere Wenzel model from the beginning,and the resultant solute concentration is controllably enhanced.So it could provide a metastable environment for crystal growth and was beneficial to the growth of protein crystals.Therefore,the crystal quality on the superhydrophobic surface was high and the XRD diffraction signal was strong.The electron diffraction pattern proves the protein crystal as a single crystal.Secondly,this thesis used the common silicon-based superhydrophobic surface as a control to examine the role of the protein-based surface in the crystallization process.The study found that the protein-based surface had some special functional groups such as amino group,carboxyl group,thiol group and so on,which had a good effect on protein crystallization.The XRD showed the single crystalline form of the crystals grown on the protein-based surface compared with the silicon surface;the electron diffraction spot showed a single crystal-like pattern.Finally,the protein-based superhydrophobic surface is applied to the crystallization of ConA,insulin,and peptides,and correspondingly regular crystals were obtained in inorganic salt environment with a low concentration.(2)Preparation of protein-based coating for reducing the adhering residual liquid foodAt present,people are trying to ease the world food crisis through various means.However,the waste of food requires to be largely reduced.Therefore,in this thesis,a protein coating for reducing the adhering residual liquid food is prepared to resolve this problem.The micro-nano structures constructed by phase-transited lysozyme are used to chemically and physically modify the surface with low-energy substances to create a sparingly liquid residue on the protein-based coating.PDMS is filled in the coating voids to act as a "liquid lubricant" so that the surface of the liquid easily slipped to achieve anti-sticking effect of food residue.It is suitable for the anti-adhesion of commercial drinks,beer,and various brands of yoghurt that the static contact angles are up to 145° on the coating surface.When the tilt angle is 8° or more,the yoghurt droplets can smoothly slide off.So as to achieve the purpose of non-sticking of high-viscous food droplets.