Preparation Of Graphene/Boron Doped Diamond Film And Its Application In Sensors

Boron-doped diamond?BDD?has low background current,wide potential window,and chemical stability.Graphene has high electron mobility,large specific surface area and good biocompatibility.Both BDD and graphene are suitable for the preparation of biosensors.In this paper,we studied the preparation,modification and electrocatalytic activity of BDD and vertical boron-doped graphene?VBG?,and constructed a high-performance electrochemical immunosensor based on them for the simultaneous detection of carcinoembryonic antigen?CEA?and carbohydrate antigen CA125.We have fabricated BDD films on tantalum?Ta?substrates using electron assisted hot filament chemical vapor deposition?EA-CVD?equipment and have carried out two studies:i)Preferential etching of{111}planes by nickel-assisted hydrogen/argon plasma etching results in the nanoscale rectangular holes and triangular?or hexagonal?holes being etched on{100}and{111}planes of BDD,respectively.This nano porous structure increases the effective electroactive surface area and reduces the charge transfer resistance of the electrode.ii)The EA-CVD method was used to vertically grow graphene with different boron doping ratio on the surface of BDD.The gold nanoparticles were in situ prepared by electrochemical reduction method to construct the Au-VBG/BDD/Ta electrode.Antigen,antibody and probe vector were effectively immobilized on the electrode surface to construct sandwich-type structural immunosensor,and different concentrations of CEA and CA125 were tested by differential pulse voltammetry?DPV?.The probe current of sandwich immunosensor based on Au-VBG/BDD/Ta electrode is directly proportional to the logarithm of antigen concentration.The corresponding detection limits of two tumor markers of CEA and CA125 are 0.16 pg mL^-1 and 0.08 mU mL^-1,respectively.This method is actually suitable for the detection of CEA,CA125 and other tumor markers in human body fluids.The innovation of this paper is that the nickel-assisted hydrogen/argon plasma etching process is used to etch regular nano-holes on the surface of boron-doped diamond to form highly electrocatalytic porous boron-doped diamond.The EA-CVD method was used to prepare vertical boron-doped graphene/boron-doped diamond electrodes by changing the growth parameters in a one-step process for the enzyme-free simultaneous determination of two tumor markers,CEA and CA125.Neither of these two studies have been reported.It is worth mentioning that neither of these two studies have been reported yet.