Captavidin as a regenerable biorecognition element on boron-doped diamond for biotin sensing

Captavidin, a nitrated avidin with moderate affinity with biotin, irreversibly adsorbs on carboxymethylcellulose to form a regenerable biorecognition element for biotin. This layer was retained and stabilized on a boron-doped diamond electrode by a Nafion film for repeated impedance analyses of biotin down to below 1 nM. The labeless electrochemical sensing scheme was then demonstrated for the analysis of biotin in blood plasma. The incorporation of captavidin confers detection specificity and regenerability, whereas the Nafion and carboxymethylcellulose layers circumvent the diffusion of endogenous electroactive species. The biosensing layer is simply regenerated by applying oxidation of +2 V for 1 min instead of its submersion in carbonate buffer for 10 min. [Display omitted] •The use of captavidin with moderate affinity for biotin to form a regenerable sensing layer for biotin on boron-doped diamond.•Captavidin confers specificity/regenerability, while Nafion and carboxymethyl cellulose circumvent electroactive interferents.•With a detection limit below 1 nM, our label-free approach rapidly screens high concentrations of biotin in blood plasma.•A rapid and convenient method for screening biotin in blood, which causes significant interference in immunoassays.