Graphene-Gold Nanoparticle-modified Electrochemical Sensor for Detection of Kanamycin Based on Target-induced Aptamer Displacement

A highly sensitive and selective label-free electrochemical sensor was developed for the determination of kanamycin. To improve the sensitivity of the electrochemical sensor, graphene-gold nanoparticles were prepared by a one-step electrochemical coreduction process and were modified on the surface of a glassy carbon electrode. The double-stranded DNA(ds-DNA) duplex probe was immobilized onto the graphene-gold nanoparticle-modified electrode. The introduction of target kanamycin induced the displacement of aptamer from the ds-DNA duplex into the solution. Methylene blue(MB) as a redox indicator monitored the current change using differential pulse voltammetry. Under optimal conditions, the designed electrochemical aptasensor exhibited a wide linear range from 0.1 pmol/L to 10 pmol/L with a detection limit of 0.03 pmol/L for kanamycin. The experimental strategy enabled the direct analysis of milk samples, and the results showed high sensitivity and good selectivity.