Development And Application Of Protein-based Porous Materials Via Pickering High Internal Phase Emulsion Templates

Due to its unique pore structure and physical properties,porous materials have great application value in many areas,and have become a hot research issue.Porous materials prepared by the traditional oil-in-water emulsions have a limited application range because the internal pores are mostly cell-closed.The preparation usually requires a large amount of surfactant or synthetic polymer and the process is potentially harmful to the ecological environment and human health.The Pickering High Internal Phase Emulsion(HIPEs)template method stabilized by solid particles is not only non-toxic and environmentally friendly,but also simple to operate and has high stability.Aiming to prepare a hydrophilic porous material with open-cell structure,good mechanical properties,antibacterial,heavy metals adsorbable and other excellent properties,this research used gliadin particles(GP)and its composite particles as Pickering emulsifier to construct a protein-based Pickering HIPEs template.The main findings are as follows:1.Porous materials with open-cell structure were prepared using Pickering HIPEs template stabilized by self-assembled gliadin particles(GP).The effects of protein particle concentration and oil phase volume on the properties of HIPEs and porous materials were systematically investigated.The result showed that under pH4.0 environment,GP concentrations of 1.5%,2.0% and 2.5% and oil phase volume of 75%,80% and 85% can be used to prepare stable porous materials using HIPEs templates.Scanning electron microscopy(SEM)and mechanical properties tests showed that as the protein concentration increases,the internal structure of the material becomes thicker,the apparent density increases and the compressive modulus increases;as the oil phase volume increases,the internal pore size of porous materials and the number of through holes increases,while the apparent density and the compressive modulus decreases.2.Nanoscale silver-loaded gliadin colloidal particles(GP-Ag)were prepared by selfassembly of Trisodium citrate green reduction combined with anti-solvent protein,and antibacterial porous material with open-cell structure was prepared by using Pickering HIPEs template stabilized by GP-Ag loaded with nano-silver.Transmission electron microscopy(TEM)and particle inhibition zone results that AgNPs(3-5 nm)prepared by green reduction were evenly distributed in gliadin,and GP-Ag can effectively inhibit the growth of Staphylococcus aureus and Escherichia coli.In particular,with the same Ag equivalent,the antibacterial property of the silver-loaded porous material is superior to that of the antibacterial protein particles(GP-Ag),indicating that it would effectively enhance the antibacterial effect by bringing nano-silver into the pore wall of the material via silver-loaded colloidal particles interface adsorption.In addition,compared with the GP single stable HIPEs,the GP-Agstabilized Pickering HIPEs emulsion has higher stability,and the obtained porous material is more robust.3.Composite particles having different surface charges were prepared by reacting cationic polysaccharide(chitosan)or anionic polysaccharide(pectin)with gliadin in an antisolvent process.This research prepared a novel porous material with controllable surface charge by Pickering HIPES template stabilized by composite particle,and systematically studied the microstructure of the porous material as well as the adsorption properties of heavy metal ions.The results showed that at a concentration of 2.0%,both the two types of composite particles can be used to prepare stable porous materials by HIPEs template with oil fraction of 80% Compared with GP,the porous materials prepared by GPP and GCHP have stronger internal structure,better mechanical properties and stronger adsorption to heavy metals.Adsorption experiments on lead and cadmium showed that the porous material prepared by GPP has stronger adsorption capacity of heavy metal ions.When immersed for 720 min,its adsorption capacity of lead and cadmium ions in the porous material was as high as 30.93 mg/g and 24.91 mg/g,respectively.