Gold-nanoparticle-decorated boron-doped graphene/BDD electrode for tumor marker sensor

A boron-doped graphene (BG)/boron-doped diamond (BDD) composite film was obtained by continuously growing BDD and BG by chemical vapor deposition. In this process, the sp 3 C C bonds in the diamond phase structure are directly converted into sp 2 C C bonds in graphene to combine the two carbon materials, while BG nanosheets are vertically grown on the exposed planes of BDD crystals. These process features impart the vertical BG (VBG)/BDD film a large specific surface area and high electrocatalytic activity, resulting in an electroactive surface area of 2.35 cm 2 . Electrodeposition can be used to load a large number of Au nanoparticles (NPs) on the VBG/BDD electrode. The Au-VBG/BDD electrode was used to construct an immunosensor capable of simultaneously quantifying carcinoembryonic antigen (CEA) and carcinoma antigen 125 (CA 125) at concentrations of 0.5–100 pg mL –1 and 0.5–100 mU mL –1 , respectively, with corresponding detection limits of 0.15 pg mL –1 and 0.09 mU mL –1 . This method is suitable for the practical detection of CEA, CA125, and other tumor markers in human body fluids, allowing early cancer diagnostics and timely treatment.