Encapsulation Of Enzyme In Pickering Emulsion Droplets For Enzymatic Reactions

Lipase represents a versatile class of biocatalysts with numerous potential applications,one of the most advantages is that it can be completely dispersed in the water phase to achieve the favorable reaction efficiency.In this article,we use BCL as catalyst to convert the transesterification of alcohol with vinyl acetate in static Pickering emulsion system.Meanwhile,the efficient separation and recycling of BCL are also been achieved.Herein,we demonstrate a general strategy for static biphasic reactions that does not required specialized devices or special additives,and is based on transferring a biphasic system to one Pickering emulsion phase.It is demonstrated that such a stirring–free reaction system gave significantly enhanced reaction efficiency as compared to conventional biphasic systems even under vigorous stirring,which is attributed to the large reaction interfacial areas and the short molecule distances created by the droplets.The specific activity of BCL in this system was found to depend on the water droplet size,revealing the importance of the presence of droplets in the reaction system.Moreover,the efficient separation and recycling of BCL are also been achieved through simple demulsification by centrifugation.After 6 reaction cycles,the conversion could be still maintained as high as 86%.This stirring-free Pickering emulsion system provides an effective means for boosting the transesterification efficiency and facilitating recycling enzyme.The microcapsules were fabricated by a chemical cross-linking method based Pickering emulsion as template.Their particle sizes,wall thicknesses and pore diameters could be finely engineered.We use this kind of microcapsule to immobilized catalyst for two phase catalytic reaction,which is what we called the crosslinking methods to"reinforcement"Pickering emulsion,make Pickering emulsion on the basis of the original packaging function,its mechanical strength is optimized,broaden the scope of its application.The morphology and structure of emulsifier were fully characterized by SEM,EDS and N₂ physical sorption.The permeability,mechanical strength and polar solvent resistance of microcapsules were also investigated.Fluorescent molecular probes were utilized to explore the permeability of the microcapsules.It was found that the microcapsules allow uptake and release of fluorescent molecules through the silica shell.The mechanical strength tests verified the availability of the microcapsules for industrial fixed bed,which could be still stable under 1 MPa of hydraulic pressure even after 45 hours.Then the microcapsules were shifted from octane to ethanol,acetone,DMF and DMSO,it's morphology still constant.These unique properties of the obtained microcapsules including excellent mechanical strength to withstand high pressure,high temperature and strong polar solvent,ensured their applicability in fixed bed.The catalytic performance of the microcapsules encapsulated with CALB enzyme.The microcapsules in continuous flow reaction system were applied in transesterification reaction of ethyl butyrate and butane whose substrate concentration is 0.1 mol/L and flow rate was 2 mL/h,the conversion is 95%.Notably,the conversion is still maintained after 720 h.These experiments results further indicating that the microcapsules are applicable and stable in continuous flow reaction system.