Application of chitosan/Fe3O4 microsphere-graphene composite modified carbon ionic liquid electrode for the electrochemical detection of the PCR product of soybean Lectin gene sequence

► A Fe3O4 microsphere, graphene and chitosan nanocomposite material modified carbon ionic liquid electrode was fabricated. ► DNA was immobilized on the modified electrode surface to get an electrochemical DNA biosensor. ► The specific ssDNA sequence can be detected in the range from 1.0 × 10−12 to 1.0 × 10−6 mol/L with the detection limit as 3.59 × 10−13 mol/L.