Construction Of Two-dimensional Biological Nanomaterials Based On Interfacial Self-assembly Strategy

Supramolecular chemistry is one of the most popular branches of chemistry today,focusing on the multicomponent subsystems produced by non-covalent electrostatic,hydrophobic,hydrogen bonding,metal ligand coordination,van der Waals forces,and?-?stacking interactions.Supramolecular self-assembly has become an important method for"top-down"synthesis of materials in recent years due to its diverse and convenient assembly strategies.And the prepared materials or structures play a key role in the fields of biocatalysis,photoengineering,medical treatment,water treatment and so on.With the rise of biology,biomacromolecules(proteins)have attracted more and more attention by material scientists for their advantages of good biocompatibility and biodegradation.In addition,one of the characteristics of protein is that amino acids with different charges are distributed on its surface,resulting in different isoelectric points of each protein.According to the relationship between isoelectric points and p H,proteins can be made to have different charges by adjusting the p H value of solution.This advantage lays a good foundation for the construction of biological functional materials based on electrostatic interaction.In addition,a clear biological structure and function is also a major feature of the protein.What is more interesting is that the structure can be folded and unfolded through different stimulus responses,so as to realize the transformation of a variety of protein forms.Therefore,a variety of supramolecular structures,such as vesicles,two-dimensional nanosheets,nanowires and nanocages,can be constructed according to the characteristics of proteins and through scientific design of protein driving forces and precise regulation of protein assembly behavior,etc.Interface assembly is a recently popular way to drive supramolecular assembly.Due to its simple process,low energy consumption and environmental friendly assembly characteristics,it has been paid more and more attention by scientists.Combining functional proteins with advanced assembly technology,protein assemblies with unique and novel functions are constructed,thus unveiling the mysterious veil of developing novel biological functional materials.This thesis proposes to construct functional assemblies based on simple interface assembly methods with electrostatic interaction as the driving force of assembly and realize the construction of biological functional materials by regulating the structure of proteins.1.Construction of protein membrane dynamic regulation molecular separation based on interface assembly strategy.Developing the ultrathin membranes for high-perfermance separation still faces the challenge of both high permeance and selectivity.Herein,a large-area protein membrane was fabricated by interfacial self-assembly of bovine serum albumin(BSA)and surfactants at the oil/water interface of emulsions.Benefiting from the ultrathin thickness and unique protein-surrounded tortuous channels,the membrane displays ultrahigh permeation flux and selective sieving capability for various molecules ranging from small dye molecules to proteins based on a dual filtration mechanism.More importantly,the rejection precision can also be reversibly regulated by the folding/unfolding transition of proteins to control the effective pore size of transport channels,even under a pressure-driven condition.This dynamically tunable ultrathin protein membrane combines the advantages of high permeance,selectivity,controllability,recyclability,and mechanical stability,which may create new opportunities for advanced applications in extended fields.2.Construction of Bionic Antibacterial Materials Based on Interface Assembly Strategy.Antibiotic-resistant bacteria have seriously threatened human life and health,and millions of patients are suffering from these health and life-threatening bacterial diseases every year.Therefore,finding an effective substitute against drug-resistant bacteria is a key factor in solving the problem of antibiotic resistance.In this chapter,we use glucose oxidase and porphyrin derivatives as the building blocks.Negatively charged glucose oxidase and positively charged porphyrin derivatives are assembled into two-dimensional nanosheets at the interface through electrostatic interaction.As we all know,glucose oxidase can catalyze the oxidation of glucose by oxygen in the air to produce H₂O₂,which can effectively kill bacteria.Porphyrin molecules are the most common photosensitizers.Under light conditions,they can absorb light at a specific wavelength to form singlet oxygen ROS.ROS can kill pathogenic bacteria by destroying bacterial cell membranes or DNA.Due to the combination of the two,the nanosheet exhibits highly effective antibacterial activity.