Development of an electrochemical DNA biosensor for the detection of vitamin B12 (cyanocobalamin) at a carbon paste modified electrode with a manganese(II) complex

Abstract

A simple, fast, sensitive and selective electrochemical detection of vitamin B 12 (cyanocobala-min) has been developed using a DNA electrochemical biosensor and a modified carbon paste electrode. Carbon paste electrode was modified with electrochemically produced polymer of [Mn(thiophenyl-2-carboxylic acid) 2 (triethylonamine)] using cyclic voltammetry with a scan rate of 0.01 V/s and three number of scans. Vitamin B 12 was immobilized onto the modified electrode. Measurements were carried out using adsorptive transfer square wave voltammetry. Detection was achieved from 3.667 μg/L to 236.0 μg/L, presenting sufficiently low detection (i.e. 1.210 μg/L) and quantification (i.e. 3.667 μg/L) limits. The precision was tested showing excellent results (i.e. from 5.50 % and 5.35 %). The selectivity towards certain interferences was also investigated and revealed that none of them had significant effect on the detection of vitamin B 12 . The electrode has been applied in the determination of Vitamin B 12 in human urine sample.