Study On Applications Of Enzyme-mimicking Metal Oxide In Biosensor

With the continuous development of biotechnology,biosensor catches the attention of more and more researchers.As a very important detection tool in biochemistry,biosensor has broad application prospects in fundamental research,food analysis,clinical medicine and diagnosis,environment security detection,process control and testing and so on.Currently,enzyme biosensor is widely used.The fundamental principle is that enzymes are used as sensitive materials of enzyme biosensors,and through testing the measurable signals of physical or chemical parameters which are proportional to the concentration of the target,quantitative analysis of the target substrate will be achieved.Enzyme biosensor has the advantages of fast response,high sensitivity,simplicity and so on.Enzymes have significant advantages,such as high catalytic activity and strong specificity.However,enzymes are highly dependent on the environment.They are easy to become inactivated in high temperature,strong acid,strong alkali,and so on,which makes the stability of enzyme biosensor poor and life of enzyme biosensor short.With the further study of nanomaterials,researchers have found that certain rare earth,transition metal oxide nanomaterials have enzymatic activity.Compared with the natural biological enzymes,they have the advantages of simple preparation,strong stability and low cost,and they can replace enzymes as biosensor sensitive materials.These studies provide an opportunity for the development of new biosensors.We prepared CeO₂,MnO₂,Co₃O₄ and their composite oxide nanoparticles,finding that they have catalytic activity similar to oxidase.In addition,the applications of enzyme-mimicking metal oxide in biosensor were realized.The following results have been achieved:1.We developed a new type of detection system for hydrogen peroxide and glucose based on the characteristic of CeO₂ with oxidase,which is a reaction system about Ce?OH?CO₃·H₂O/H₂O₂/TMB.After sequential addition of H₂O₂ and TMB to Ce?OH?CO₃·H₂O powders,a typical color reaction occurred in a slightly acidic aqueous solution.The color depth varies in accordance with the H₂O₂ concentration,which realized the colorimetric determination of H₂O₂.The linear response concentration of H₂O₂ was in the range of 0-80 ?M,the detection limit was 0.3 ?M,and the relative standard deviation was less than 5.1%.After modification,this reaction system could allow the detection of glucose.The linear response concentration of glucose was in the range of 0-140 ?M,the detection limit was 0.4 ?M,and the relative standard deviation was less than 5%.2.Ce-Mn and Co-Mn composite oxide nanoparticles were prepared by oxidation-reduction method.In the colorimetric detection experiment TMB,OPD and so on as substrates,we found that Ce-Mn and Co-Mn composite oxide nanoparticles have the catalytic activity similar to oxidase,are able to work in a slightly acidic environment without inactivation,and have a wide working range of temperature sensing,and strong reusability.These materials can be used to develop new stable biosensors.In addition,these oxides can be highly efficient to catalyze oxidation of TMB,Az BTS,DOPA and so on.They can be used to degrade environmental pollutants.3.The color reaction occurs when the metal oxides and their composite oxides catalyze TMB,Rh640 and so on.The essence of this reaction is the redox reaction and electron transfer.The prepared composite oxide materials were coated on a glassy carbon electrode as a biosensor electrode to test cycle voltammetry curve.The results showed that these materials played the role of electron transfer media in the process,and they could accelerate the electron transfer.Therefore,the application of these materials to biosensors can greatly improve the detection sensitivity of biosensors.