The Construction Of A Non-enzymatic Biosensor Based On Carbon Nanocomposites And Its Application In The Detection Of Natural Anticancer Substances

Cancer is one of the common health problems of the world.Population studies have shown that cancer risk reduction associated with fruit and vegetable intake.Thus,naturally occurring plant chemicals has a great potential for cancer prevention.Drugs developed from natural materials are indispensable sources of molecular and mechanism diversity in the anticancer drug.In order to obtain better anti-cancer effect,the concentration of natural anticancer substances needs to be strictly controlled for subsequent drug design and processing.Therefore,the detection of natural anticancer substances is very necessary.Enzyme based biosensors and non-enzymatic biosensors have attracted much attention.However,by reason of the thermal instability,poor storage stability and environmental influence of enzyme,the application of enzyme biosensor was once limited.As a new generation of biosensor,non-enzymatic biosensor does not need any natural enzyme as recognition element,and has high sensitivity,good stability and low price.In order to increase the effective active area and binding sites of the substrate materials,we prepared nanomaterials with high conductivity and catalytic activity.Metal matrix nanocomposite modified electrode was used to construct non-enzymatic electrochemical biosensor.The performance of the biosensor was adjusted by changing the size,morphology and composition of metal nanoparticles.Development of specific biosensor detection method for sensitive analysis of natural anticancer substances in complex samples.The specific research contents can be summarized into the following two parts:（1）Graphene oxide（PEI-RGO）nanocomposites were synthesized by the nucleophilic substitution reaction between the active amine group in polyethylenimine and the epoxy group on the surface of graphene oxide.On this basis,Pt and Pd were selected to prepare core-shell cubic bimetallic alloys,which were uniformly distributed on PEI-RGO,showing higher catalytic activity,excellent catalytic selectivity and even better anti-deactivation activity than single metal nanostructures.Benefiting from the synergistic effect of these advantages,the final gallic acid sensor shows high sensitivity,selectivity and stability.It shows the wonderful amperometric response to gallic acid in the linear range of 10μM-4.5m M,with limit of detection（LOD）of 4.56μM,which improves the performance of the existing gallic acid sensor and provides a reference for the development of gallic acid sensor with higher analytical performance gallic acid sensor provides a new idea.（2）Amino functionalization has been applied in carbon materials to enhance the controllable covalent bond of polymer or biomolecule.In this experiment,graphene oxide was modified into amino reduced graphene oxide（NH₂-RGO）by hydrazine hydrate and ammonia water.The formation of NH₂-RGO was verified by X-ray diffraction,X-ray photoelectron spectroscopy and TEM.Based on the exploration in the previous chapter,we try to synthesize waxberry like compounds composed of different metal elements Au@Pt Pd trimetal nanorods were used in combination with NH₂-RGO and were coated on the glassy carbon electrode.It turns out that Au@Pt Pd NRs-NH₂-RGO is an excellent electrochemical sensing platform.Cyclic voltammetry and differential pulse voltammetry were used to test the detection performance of chicoric acid.The results showed that the linear range of response was 0.1μM-70μM,the minimum detection limit was 0.038μM,and the sensitivity was 14.6μAμM^-1cm^-2It was successfully applied to the determination of chicoric acid in chicory with satisfactory results.