A Label-Free Electrochemical Biosensor Based on a Reduced Graphene Oxide and Indole-5-Carboxylic Acid Nanocomposite for the Detection of

A label-free DNA hybridization electrochemical sensor for the detection of Klebsiella pneumoniae was developed, which could be helpful in the diagnosis of bacterial infections. Indole-5-carboxylic acid (ICA) and graphene oxide (GO) were electrodeposited on a glassy carbon electrode, and the resulting reduced GO (rGO)-ICA hybrid film served as a platform for immobilizing oligonucleotides on a single-stranded DNA (ssDNA) sequence. The conditions were optimized, with excellent electrochemical performance. A significant change was observed after hybridization of ssDNA with the target probe under optimum conditions. Hybridization with complementary, noncomplementary, one-base mismatched, and three-base mismatched DNA targets was studied effectively by differential pulse voltammetry. The proposed strategy could detect target DNA down to 3 × 10-11 M, with a linear range from 1 × 10-6 M to 1 × 10-10 M, showing high sensitivity. This electrochemical method is simple, free from indicator, and shows good selectivity. Hence, electrochemical biosensors are successfully demonstrated for the detection of K. pneumoniae.