Research On Construction Novel Mimetic Enzyme Based On Bio-inspired Nanostructures

Life through millions years of evolution is almost completed intelligent controlall life processes. Learning from nature, artificial intelligence is the eternal theme ofnew materials and novel systems development. Natural enzymes could skillfullyregulate every biological process as biocatalysts in all living organisms. However, theproteins consist of natural enzymes, which practical application is restricted by poorstability. To obtain high efficiency and stability of the enzyme mimics has become acurrent research focus. Nanomaterials with its large surface area, surface energy, highbiocompatibility and other new features, has been widely used in constructingmimetic enzymes in recent years. Just under this research background, by use ofbiochemistry, nanochemistry, interface chemistry and other comprehensive researchmethods, a class of nanomatrials and systems with nature enzyme-like activity havebeen designed and synthesized. It will promote the mimetic enzyme system havingbetter biocompatibility and practical application value, and also lay the foundation forthe application of functional nanochannel materials. The primary contents of thedissertation are as follows:1) Based on natural transferrin shell which widely existed to organisms as thematerial, using the hollow spherical nanocage structure as template, through the pointcontrol technology to synthesis apoferritin paired gold clusters (Au-Ft). After thecharacterization of TEM, UV visible spectroscopic, and fluorescence spectroscopic,the results demonstrate the construction is successful and consistent with preliminarywork. A detailed study of enzymatic properties for Au-Ft has been carry out. The pHand temperature dependencies for Au-Ft is similar to nature HRP. The optimalreaction condition for Au-Ft is pH4.0,45°C. Compare with larger gold nanoparticles, Au-Ft has significant higher catalytic activity, and ferritin shell could enhance thereaction activity. Au-Ft has better pH stability, and still has activity in hightemperature environment. Steady state kinetics show that it follow theMichaelis-Menten properties, and determine the reaction mechanism consistent with aping-pong mechanism. The Kmvalue for Au-Ft is lower than natural enzyme towardsTMB, and the Kmvalue for Au-Ft is higher than natural enzyme towards H2O2, whichexhibit different substrate affinity. Finally, we construct a simple and fast method forthe detection of glucose by combining the nanozyme with GOx.2) Based on bionic intelligent nanochannel, ion track and chemical etching method,we prepared asymmetric single nanochannel with diodes rectification propertyThrough EDC/NHS method, a bioactive peptide (SRGDU) with GPx activity center ismodified on the inner surface of single conical nanochannel. Se as reactive centerexpose to GSH and tBuOOH, which cause changes on effective channel diameter ofnanochannel. When the enzyme channel system react with GSH and tBuOOH in turn,the rectification intensity and current were decreased firstly and then increased. Theresponse to tBuOOH increased following the increasing concentration of substrate. Inthe contrast experiment, both nanochannels without modified and with comparativepeptides exhibited the contrary changes. The mimetic enzyme system also havereversibility with three times response. This bionic intelligent simulation systemprovides a new design idea to develop the mimic enzyme.3) This paper has also carried on the application of bionic intelligent nanochannel inbiological toxin detection. Fumonisins (fumonisin B1) mainly exist in agriculture. Itnot only pollute food and related products, but also cause potential carcinogen andtoxic of certain animals. Based on the biomimetic intelligent channel materials, wedesign asymmetric nanochannel detection system with fumonisin response. Wemodified fumonisins antibody to inner surface of intelligent channel for thepreparation of detection device with specific response to fumonisins via a chemicalmodification method. As increasing the response concentration of toxin, therectification ratio of functional nanochannel presents an obviously decrease. Naked nanochannel do not show the variation of current and the rectification ratio after reactwith a series concentration of fumonisins. This study is based on the intelligentbiomimetic nanomaterial, the construction of new fumonisin detection system, andprovides a new idea for the detection of biological toxins.In conclusion, this thesis follows the idea of learning from nature by usingnatural apoferritin protein as a template to preparing Au-Ft. We found the peroxidaseactivity of Au-Ft for the first time. Furthermore, we examine its enzymatic properties,reaction mechanism and applied it to detect glucose at physiological level. Then basedon biomimetic nanomaterials, we construct the simulation system with GPx-likeactivity. The current intensity and rectification ratio changes are used to evaluationsystem in response to substrate. At the same time, we also successful construct a newmethod of fumonisin detection via combining the biomimetic nanomaterial withbiological toxin detection.