Preparation And Property Of A Biosensor Based On Flexible Substrate Graphene Network

Biosensor is an important technique in analytical biotechnology.It is a multi-disciplinary production,which combines biology,analytical chemistry,materials science,information science and related technical detection of biological material for fast analysis and tracking.The arise of biosensors is driven by the interests of scientists and social development.After 40-years' development it has become an energetic field.This thesis focuses on following two aspects:(1)A biosensor was designed based on graphene oxide and simulation in vivo environment.Graphene oxide is a common derivative which has a lot of oxidation groups so that it is available for connecting metal oxide nanoparticles.Due to the intermolecular forces,the graphene oxide with metal oxides has weak mechanical and difficult to make electrode.So we added in PVA(Polyvinyl Alcohol)when making r-GO@WO3,which enhanced the mechanical property.Then we found that r-GO@WO3 possessed intrinsic capability to catalyze the redox of hydrogen peroxide as peroxidase mimics.And we tested the sample by colorimetric and electrochemistry.Colorimetric can visualize the biochemical reaction through visual changes.Owing to unnecessary of large analytical instruments,colorimetric is a cheap and quick analysis method.Then we tested the performance of its detection of hydrogen peroxide.But its sensitivity and linearity are not comparable to electrochemistry.Then we detected the Dopamine by electrochemistry.Dopamine is a biomolecule which is essential for human body.We found r-GO@WO3 showed good performance in both colorimetric and electrochemistry.(2)A biosensor was designed based on a flexible substrate.The biosensor was based on the carbon fiber(CF)and grown with graphene oxide(GO),multi walled carbon nanotubes(MWCNT)and ZnO nanocrystals.Its mechanical performance has not changed much after grown so many materials on it.It is so flexible to curve or fold.And this biosensor is accommodated biomolecules,bacteria or even cells to resemble the in vivo 3D environment,which provides a basis for simultaneous testing of the analyte.The r-GO enlarges the surface area and its large amounts of oxygen-containing groups provide reaction sites to connect the others.MWCNT enhances its electrical conductivity.ZnO nanocrystals act as reactive sites.The high specific areas of ZnO nanocrystals enlarge electrochemical catalytic active sites.The synergy of these materials makes the biosensor have a sensitivity of 2.75 mA mM-1 cm-2,3 s response time and good specificity.