Preparation And Biosensing Application Of Nano-porous Three Dimensional Graphene-like Carbon Materials

Biosensor is a cross-discipline product of physical,chemical,biological and information science and other related technology,which is more and more widely used in clinical diagnosis,farming husbandry,food industry and environmental protection.There are a lot of opportunities and innovations in this field.Graphene due to its good conductivity,wide electrochemical window,stability,biocompatibility is widely applied in biosensing.However,the 2D graphene cannot make the best of its large specific surface area,whose hydrophobicity is not conducive to the biochemical reaction in aqueous environment either.This paper mainly studied the following three aspects to overcome these challenges and prepare a biosensor with higher performance.(1)The nano-porous 3D graphene-like carbon materials were prepared.The compound bio-electrode is the key unit of an electrochemical biosensor based on biochemical reaction to output electric signal.Generally,a larger number of active substances loaded on the bio-electrode with larger surface can more effectively improve the performance of the sensor.In this paper the innovative continuous-molding-template was employed to prepare three-dimensional porous grapheme-like carbon materials which can form monolithic electrode with nano-pores whose size range from 100 to 200 nm and even decrease to sub-100nm.By adjusting the pore-size,the internal space of electrodes will be more effectively used,the inside surface will be enlarged,and there arise more sites for bioactive substances to be attached to.The new material provides a new way for the preparation of composite bio-electrodes and sensors with high performance.(2)3D graphene and graphene-like carbon materials were modified functionally.The electrochemical biosensor depends on the reaction between the electrode and determinand.In addition to larger internal surface area for higher density of active site participated in the reaction,promoting the activity of a single site can also facilitate the reaction rate to improve the performance of the sensor.3D graphene or graphene-like materials are inert and hydrophobic for the lack of functional groups on the surface.However,the most reactions of biological matters occur in the aqueous environment,so hydrophobicity is against the reaction.In this paper the inert graphene or grapheme-like materials were modified with functional groups through diazo chemical and oxidation.As a result,the introduction of hydrophilic groups improved the hydrophilicity and activities of the materials.The existence of functional groups may also be used for chemical adsorption of some bioactive substances to promote the rate of electron transfer between active materials and the electrode,which is favorable for the preparation of more sensors.(3)In this paper,the pore-size of prepared nano-porous three-dimensional grapheme-like material was controlled to nanoscale.The material has a very good response to hydrogen peroxide with sensitivity of 87?AmM-1cm-2 and linearity ranging from 30?M to 18mM because of abundant defects due to topology.But it takes long time to reach the steady state of current.After it was integrated with copper,the sensor for hydrogen peroxide was prepared.The conductivity of copper and the response of grapheme-like carbon materials to the hydrogen peroxide get the sensor excellent performance with sensitivity of 400pA/mM/cm2 and linearity ranging from 35?M to 6.5mM.And response time reduce from 10s to Is.