Aqueous Synthesis And Catalytic Properties Of Enzyme-contained Microgels With Semi-interpenetrating Network Structure

Energy issue is a great challenge for human beings in 21 century.At present,fossil fuels are the most important energy sources in human society,which are non-renewable and formed over millions year.The burning of fossil fuels leads to large emissions of anthropogenic CO2,nitrogen oxides and sulfur oxides,causing a series of environmental problems.This has forced people to look for clean and renewable energy.Enzymes catalyze reactions with the properties of high catalytic efficiency and high exclusive performances and mild conditions,provide a green and feasible approach for reducing CO2 into methanol,while methanol is a clean and renewable energy.A combination of formate dehydrogenase,formaldehyde dehydrogenase and alcohol dehydrogenase can reduce CO2 into methanol with the present of reduced nicotinamide adenine dinucleotide.However,the enzymes have the shortcomings of poor stability,difficult recovery and high price.Immobilizing enymes into suitable carriers using appropriate methods can overcome the above shortcomings.Stimuli-responsive microgels have outstanding characters of stable and transparent structure,good biocompatibility,small size,large specific surface area and rapid respond towards environment stimulus,which makes stimuli-responsive microgels as a perfect carrier for enzymes immobilization.Immobilizing enzymes into microgels by semi-interpenetrating network is well able to maintain the activity of enzymes and avoid enzymes leakage.So far most of enzymes immobilization by semi-interpenetrating network achieved through inverse emulsion polymerization.Inverse emulsion polymerization used organic solvents,which could reduce enzymatic activity and selectity.Therefore,aqueous synthesis of enzyme-contained microgels with semi-interpenetrating network structure is significant.Some research about this method has been carried out,but it needs further development.Herein,we synthesize enzyme-contained microgels with semi-interpenetrating network structure in aqueous through simple operation and study their catalytic properties.(1)We prepare alcohol dehydrogenase-contained ADH@PNA microgels in aqueous,and such microgels exhibit the enhancement of catalytic properties compared with free ADH.(2)We prepare formaldehyde dehydrogenase-contained FaDH@PNA microgels in aqueous,which have higher thermal stability,formaldehyde yield and affinity for reduced nicotinamide adenine dinucleotide.(3)We prepare ME@PNA microgels in aqueous which contain formate dehydrogenase,formaldehyde dehydrogenase and alcohol dehydrogenase.ME@PNA microgels can reduce NaHCO3 into methanol,and show different catalytic performance with free enzymes.