Design For New Types Of Self-assembled Pickering Emulsion And The Application In Enzyme Immobilization

This article is mainly to solve problems of catalysis and recyclability on immobilized enzyme in organic system.We have designed different particles and assembled a series of Pickering emulsions for enzyme immobilization.It mainly included Pickering emulsion stabilized by hydrophobic SiO₂ and Fe₃O₄@SiO₂ nanoparticles?NPs?as well as the cross-linkable colloidosome with polydopamine layer from interfacial polymerization.Furthermore,lipases were immobilized in Pickering emulsion and colloidosomes,then the catalytic property were investigated by the esterification of caproic acid and hexyl alcohol.The conclusions were drawn as follows.?1?Hydrophobic SiO₂-stabilized Pickering emulsion: hydrophobic SiO₂ nanoparticles were prepared by one step synthesis method and then used to form Pickering emulsion.It demonstrated that the particles were unable to form stable Pickering emulsion in strong polar solvents,while the solvent with weak polar such as toluene or heptane could stabilize the Pickering emulsion.In addition,with increasing content of SiO₂ loading and Ro/w,the diameter of Pickering emulsion droplets decreased gradually.?2?Synthesis of cross-linkable colloidosomes by interfacial polymerization of dopamine in a Pickering emulsion: on the basis of previous chapter,dopamine powder was added into the hydrophobic SiO₂-stabilized Pickering emulsion,and a cross-linkable colloidosome?SiN/PDACs?formed and lipsases were immobilized at the oil/water interface.The emulsion droplets were spherical and the shell of colloidosome was composed of SiO₂ nanoparticles and polymer layer.Under optimal conditions,the highest enzyme activity reached to 46.14 U mL^-1.In addition,the lipase-SiN/PDACs has a good stability and recyclability,and the retention rate of enzyme activity is respectively 80% and 86.6% after ten days and repeated for 15 times.?3?Hydrophobic Fe₃O₄@SiO₂-stablilized Pickering emulsion with a type of W/O: the magnetic Fe₃O₄ and hydrophobic Fe₃O₄@SiO₂ nanoparticles were respectively prepared by methods of coprecipitation and one step synthesis.The hydrophobic Fe₃O₄@SiO₂ nanoparticles were then used to build a new type of Pickering emulsion and applied on enzyme immobilization.The core-shell Fe₃O₄@SiO₂ nanoparticles were with a thick shell of 50 nm and the optimal enzyme activity was 15.32 U mL^-1.In addition,the specific activity of lipase maintained at 79.33% even after 8 cycles,showing a good stability and recyclability.