Electrochemical DNA-based disposable chip for the detection of Klebsiella pneumoniae: a prominent causal agent for urinary tract infections

Abstract The aim of this study was to develop an electrochemical DNA sensor for the detection of Klebsiella pneumoniae, a prominent causal agent of UTI, by immobilizing a 5’NH2-labelled ssDNA probe specific to the fimH gene of Klebsiella pneumoniae ( K. pneumoniae ) on a GQD-modified, screen-printed, disposable electrode. The present study involved the synthesis of graphene quantum dot (GQD)-based nanoparticles using a hydrothermal method and characterized them using Fourier transform infrared (FTIR) spectroscopy, particle size analysis and fluorescence spectroscopy. The synthesized nanoparticles were drop cast onto a screen-printed carbon electrode (SPCE) surface and used in electrochemical biosensors for detecting Klebsiella pneumoniae , which is among the world’s leading pathogens causing urinary tract infections. In this study, a specific NH 2- labelled probe was immobilized onto a GQD-fabricated electrode surface, and the electrochemical response was recorded by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Electrode surface characterization was performed using FE-SEM and FTIR spectroscopy. This nanofabricated chip was found to be very specific, user friendly, less time consuming and affordable to everyone. The sensor was also validated with patient samples and showed an excellent sensitivity and LOD of 70.5 mA/mm 2 /ng and 0.002 pg/µl respectively using CV.