The Design And Application Research Of Pickering Emulsions And Microfluidic Droplets As Bioreactor

The biological microreactor refers to a kind of new type bioreactor with micrometer size and high efficiency.How to control the reaction effectively and strengthen the reaction procedure is a persistent challenge.There are so many ways to trigger the emulsion reaction,but the methods suitable for enzymes with biological activity is poor,using visible light to regulate the biological reaction in emulsion droplets can yet be regarded as an efficient way.Because of the dynamic interface and large specific surface area,microfluidic droplet flow solves the thorny problem effectively that the oil-water two phase interface enzyme catalytic rate is slow.Nevertheless,the mass transfer mechanism of the oil-water two phase enzymatic reactions is still unclear.Based on this,this research focuses on the design and construction of the Pickering emulsion microreactor with visible light response and microfluidic droplets flow microreactor,studied its performance and mechanism,implementing regulation and strengthen biological reactions under microscale.For building Pickering emulsion microreactor,using short carbon chain alkyl silane grafted TiO2 nanoparticles doped nitrogen to stabilize Pickering emulsion,with the aid of visible light irradiation caused emulsion droplet coalescence and then trigger the enzymatic reaction;For fabrication of microfluidic microreactor,the coaxial flow loop structure composed of capillary glass(inner tube)nested in transparent silicone tube(outer tube),can produce slug W/O droplets flow effectively,the materials of which need no modification and simple to manufacture,under the flow rate of 30 mL·h-1,and explore the effect of flow parameters on the strengthening of the enzymatic reaction.The design and making of microreactor above laid a solid foundation for the further research on performance of the microreactor.Pickering emulsion enzymatic microreactor:with s-N-TiO2 nanoparticles produced by sol-gel method as the emulsifier,urease decomposition reaction of urea as the research object,set up a visible light-activated Pickering emulsion enzymatic microreactor,explored the effect of the amount of nitrogen doped into s-N-TiO2 nanoparticles and visible light response of the emulsion performance,nanoparticles with 1 Wt%of Nitrogen do emulsifier can form a stable W/O emulsion;In visible light around 10 h,as the surface of s-N-TiO2 nanoparticles gradually changed from hydrophobic to hydrophilic,the coalescence of emulsion droplet caused enzymatic reactions in droplets.Microfluidic droplet flow enzymatic biological microreactor:with the hydrolysis reaction of tributyrin catalyzed by lipase as the research object,studied the strengthen law of interface enzymatic reaction in microfluidic W/O slug flow,the enzymatic reaction rate of microfluidic can reach up to 2.28 μmol·mL-1-min-1,which is 20 times as much as the beaker enzymatic reaction rate.This reason is that the microfluidic slug droplet flow has large specific surface area,short mass transfer distance and high diffusion rate.Droplet size,the total flow and the bend degree of reaction channel has an important impact on strengthen the enzymatic reaction.All in all,this study focuses on visible light-activated Pickering emulsion enzymatic microreactor and microfluidic droplet flow enzymatic microreactor,which are applied to trigger urease reaction and strengthen the lipase enzyme catalytic reaction respectively.We hope to provide references for the regulation and strengthen of enzymatic microreactions in microreactors.