Preparation And Properties Of Fe-aminoclay And Its Composite Structure

Fe-aminoclay is a kind of artificially synthesized nano-material with a layered structure.Compared with natural clay,it has the advantages of adjustable structure and functional design.In addition,with the development of nanoscience,new requirements have been put forward for materials with biological and chemical properties.The development of such self-assembled materials that can combine biological,organic and inorganic materials has become an innovative platform.In this paper,Fe-aminoclay is surface modified to increase its surface active groups.Fe-aminoclay was used as the immobilized carrier,and Fe-aminoclay nano-structured lipase?Feclay-lipase?and Fe-aminoclay lipase composite structure material?Aminoclay-lipase?were constructed by different immobilization methods.The main research results are as follows:?1?Study on Preparation and Properties of Bifunctional Fe-aminoclay.In this chapter,succinic anhydride modified Fe-aminoclay is used to improve the water dispersibility of Fe-aminoclay.The introduction of carboxyl functional groups can improve the surface activity of Fe-aminoclay.XRD,FT-IR,contact angle and other testing techniques were used to characterize the bifunctional Fe-aminoclay.The results show that the layered structure of the Fe-aminoclay remains unchanged after modification,and the C=O stretching can be seen from the infrared spectrum The vibration peak and-OH vibration peak were enhanced,indicating that the carboxyl group has been successfully grafted onto the Fe-aminoclay.From the analysis of contact angle,the hydrophilicity of the bifunctional Fe-aminoclay is enhanced compared with the Fe-aminoclay.The amino and carboxyl groups of the bifunctional Fe-aminoclay increase the binding sites with protein molecules and broaden its application scope,such as drug transport and release,and immobilized carriers.?2?Fe-aminoclay is a novel type of synthetic Talc-like organosilicate clay,which has important potential application in the field of enzyme immobilization used as the nanostructured support.In the presented study,Lipase from Aspergillus oryzae was immobilized on Fe-aminoclay support via 1-?3-Dimethylaminopropyl?-3-ethylcarbodiimide hydrochloride?EDC?as covalent crosslinking agent.The nanocomposite structure of immobilized lipase?Feclay-lipase?was characterized by XRD,TEM and FT-IR.The enzymatic properties of free lipase and Feclay-lipase were studied by enzymatic kinetics.The results showed that the optimal immobilization efficiency of Feclay-lipase was 82.88%,immobilization capacity was 414.4 mg·g^-1 support,and the enzyme activity was 28.24 U/mg,which was three times higher than that of free lipase?8.21 U/mg?.The optimum reaction temperature of Feclay-lipase increased from 45?to 55?,the optimum pH shifted to alkalinity,and the catalytic activity of Feclay-lipase did not decrease significantly after storage at 4?for one month.?3?Using the combination of Fe³⁺and lipase,this chapter constructs an Fe-aminoclay lipase composite structural material?Aminoclay-lipase?,and characterizes Aminoclay-lipase by XRD,FT-IR,Zeta potential and other techniques.The effects of lipase loads on the efficiency of enzyme immobilization were studied experimentally.The enzymatic characteristics of Feclay-lipase,Aminoclay-lipase and free lipase were compared.The differences between the two immobilized lipase under different environmental conditions were discussed.The experimental results show that the optimal immobilization efficiency of lipase is 89.25%,the enzyme loading is 148.75 mg/g,and the enzyme activity is 22.12 U/mg,which is 2.6 times higher than the free enzyme.Because Feclay-lipase lipase and the carrier are linked by covalent binding,the stability is better than Aminoclay-lipase.The lipase in Aminoclay-lipase is better than free lipase in optimal temperature and pH due to the protection of the carrier.And the lipase activity was still kept above 70%after one month of storage at low temperature.