Controllable Assembly And Property Of Polyphenol-based Coacervates

Coacervate is typically the materials assembled by liquid-liquid phase separation based on intermolecular non-covalent interactions.Recent research mainly focuses on the polyelectrolyte-based coacervates driven by electrostatic interaction,which play key roles in the construction of protocells and preparation of functional materials.Since polyelectrolytebased coacervates are sensitive to salt concentration,it is limited and challenging for the application of electrostatic interaction-driven coacervates in different fields.Therefore,it is crucial to investigate the liquid-liquid phase separation process of multiple building blocks,as well as to tune their properties(e.g.,stability)for developing the functional materials.In this thesis,natural polyphenols(i.e.,tannic acid,TA)and poly(ethylene glycol)(PEG)were used as building blocks for the assembly of coacervates,which resulted in the salt-resistant coacervate materials with controllable sizes and morphologies.The assembly mechanism of coacervates was investigated and analysed using various techniques(e.g.,confocal laser scanning microscopy,nuclear magnetic resonance,dynamic lase scattering,infrared spectrum).Coacervate sizes,morphologies,and stability are tuned by the variation of concentrations and ratios of TA and PEG.Furthermore,the potential applications of coacervates,especially in bioimaging,drug loading,construction of protocells,and the intracellular regulation of radical oxygen species are investigated systematically.This thesis mainly includes the following contents.Chapter 1 is focused on the recent advances of coacervate systems,as well as their applications in the construction of the protocell model,disease diagnosis and treatment,and preparation of advanced functional materials,etc.In addition,the research progress of polyphenol-based functional materials is summarized.In Chapter 2,we introduce polyphenol-based coacervates,which are driven by hydrogen bonding,with tunable size,morphology,and stability.The underlying assembly mechanism is investigated by using different characterization methods.The size and morphology of coacervates are tuned by the variation of the concentration and ratios of the components.Specifically,the size can be controlled from 70 nm to 10 μm and the morphology can be varied from particles to capsules without the introduction of salts during the assembly.In Chapter 3,we investigate the properties and applications of polyphenol-based coacervates in drug encapsulation and intracellular regulation of radical oxygen species.During the formation of coacervates,bioactive molecules,drugs,fluorescence dyes,and inorganic nanomaterials can be simultaneously encapsulated in the polyphenol-based coacervates relying on the adhesive property of polyphenol.In addition,the unique feature of the building block endows the coacervates with the anti-oxidation feature.The obtained coacervates are expected to be applied in the field of catalysis,drug encapsulation,bioimaging and beyond.