Construction Of Protein Biomimetic Materials Based On Interfacial Self-Assembly Strategy

With the development of supramolecular chemistry and the rise of nanotechnology,self-assembly has now been thoroughly studied in the fields of chemistry,physics,biology and materials engineering,and has also become an important"bottom-up"method of preparing new materials.Various structures can be created for different applications through a variety of assembly strategies,so it not only becomes a practical method for manufacturing nanostructures,but also shows great advantages in building ordered structures with different scale.Protein has a definite structure and function.The structure is a high-level structure formed by curling and folding polypeptide chain into various secondary structures and it can achieve reversible folding and unfolding through a variety of stimulus responses,making it have diverse characteristics.It enables the unique advantage of constructing different functional assemblies by arranging protein building blocks.At the same time,controlling the strength,number,or direction of protein-protein interactions may change the self-assembly behavior of proteins.In other words,the structure of the protein,the type of connection,and the way it is arranged have a significant effect on the final self-assembling structure of the protein.Therefore,scientists can precisely regulate the self-assembly behavior of proteins by rationally designing protein-protein interactions to construct structures such as cage?linear?circular?tubular?sheet and vesicle various supramolecular structures.In recent years,the rise of interface self-assembly has provided favorable conditions for the construction of large-sized structures.Because of its simplicity and efficiency,it has attracted widespread attention from scientists.Interfacial self-assembly is also an important way to drive protein assembly.Combining protein assembly with advanced nano-biotechnology will create various novel functional protein assemblies,which will provide new directions for the development of functional biomaterials.The research in this paper is based on the interface assembly method to drive the formation of large-scale protein assembly and realize the structure and function of the assembly,so as to achieve the purpose of simulating complex biological systems,and further realize the construction of functional biomaterials.Specifically,we will develop a new method of protein interfacial assembly,utilizing a complex of functional proteins and surfactants as a building block,and using the amphiphilicity of the building block to self-assemble at the oil-water interface and form a large protein assembly.By controlling the unfolding and refolding of the protein,it can realize the regulation of the function of the bionic system“on”and“off”.1.Construction of“breathing”vesicles based on proteinosomes structureWith the rapid development of nanotechnology and nanoscience,the way of interfacial assembly has received widespread attention.Interfacial self-assembly provides an effective method for the construction of proteinosomes.In this chapter,we develop a strategy based on protein interfacial self-assembly to construct giant proteinosomes,and simulate the"breathing"process of jellyfish.We choose BSA protein as proteinosomes building block.Due to its isoelectric point of 4.7,the surface of the BSA is negatively charged in a neutral PBS buffer solution.Therefore,we use the electrostatic interaction between the positively charged surfactant CTAB and the negatively charged BSA,and then add isooctanol.The complex of protein and surfactant aggregates spontaneously at the oil-water interface.The droplets of isooctanol provide templates,which cause the proteins to form giant proteinosomes.Proteinosomes can change their size by adding and removing denaturants,resulting in a unique"breathing"behavior.Inspired by the"breathing"process of jellyfish in nature,we construct proteinosomes containing the green fluorescent protein.The unfolding and refolding of the EGFP led to the disappearance and recovery of fluorescence,achieving the purpose of reversible fluorescence on and off caused by jellyfish-like expansion and contraction.This protein assembly model will open up a whole new research idea for the construction of"live"assemblies in cell simulation.2.Construction of light-harvesting system based on proteinosomes structureIt is an ideal strategy to design and construct artificial light harvesting systems to arrange chromophores with proteins as carriers.In this chapter,we make use of electrostatic interaction between negatively charged BSA protein and positively charged CTAB,constructing huge proteinosomes based on interfacial assembly method,and design an efficient intelligent light harvesting systems.We chose rhodamine B as the acceptor molecule and FITC as the donor molecule by chemical modification to connect to the building block protein.The chromophore-modified protein could still assemble into proteinosome through the interfacial assembly strategy.The proteinosome has a hydrophilic protein shell,which makes it easy to distribute donors and acceptors,and the proteinosome can be regarded as a curled sheet structure,which shortens the distance between the donor and the acceptor.The effective energy transfer between the donor and the acceptor can take place,thus a complete light harvesting system is formed.In addition,protein unfolding induced by denaturing agents can extend the distance between donors and acceptors,thereby closing energy transfer.The protein then refolds again,enabling energy transfer to happen again.This way of protein unfolding and refolding can realize the reversible cycle of energy transfer switch.The light harvesting system is expected to be used in the development of photocatalysis and optical devices in the future.3.Construction of efficient antibacterial materials based on protein sheetstructureBacterial resistance has become a serious global challenge,and effective treatments are urgently needed to replace traditional antibiotics.Natural enzymes are expected to be used in biomedical and other fields due to their advantages of extensive antibacterial activities,good biocompatibility and not easy to cause bacterial resistance.In this chapter,we use a variety of natural enzymes as building blocks to construct multi-enzyme protein assemblies by means of interfacial assembly,and develop an efficient intelligent antimicrobial system based on multi-enzyme combined catalysis.W build the complex of lysozyme,glucose oxidase,lassase and polymer to assemble the protein sheet structure at the oil-water interface.According to the characteristics of these three enzymes,lysozyme is a natural antibacterial enzyme.Glucose oxidase can produce H₂O₂ in the presence of the substrate glucose,while laccase can generate ROS in the process of oxidizing lignin.The combination of multiple enzymes greatly promotes the antibacterial effect.At the same time,the antibacterial activity of the system can be closed by denature-induced unfolding of the enzyme,and then the antibacterial ability can be restored by inducing the enzyme refolding.This process is expected to achieve multiple reversible cycles of the antibacterial activity.The intelligent antibacterial system provides a new idea for the development of intelligent materials,and it is expected that the intelligent antibacterial materials will be applied in the fields of biomedical in the future.