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Updated: Jan 14, 2026
Bacterial Detection & Identification Using Electrochemical Sensors
Published on: April 23, 2013
Peptide nucleic acid-based biosensor for detection of E. coli with differential pulse voltammetry
Nurullah Çiftçi1, Zihni Onur Uygun2
1Faculty of Medicine, Department of Medical Microbiology, Kafkas University, Kars, Türkiye.
Aims:
This study aimed to develop a rapid and highly sensitive electrochemical biosensor for the sequence-specific detection of Escherichia coli 16S rRNA using a peptide nucleic acid (PNA) probe immobilized on a graphene - NH/gold-nanoparticle (GNH - AuNP) composite.
Materials & Methods:
An SH-terminated PNA probe was covalently attached to a GNH - AuNP nanocomposite layer deposited on gold screen-printed electrodes via 3-mercaptopropionic acid (MPA). The electrode assembly and hybridization processes were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). Quantification was achieved using differential pulse voltammetry (DPV) with hexaammineruthenium(III) (RuHex) as an electrostatic redox indicator.
Results:
Hybridization of the target 16S rRNA sequence produced a distinct "signal-on" DPV response proportional to target concentration. The biosensor exhibited excellent linearity from 1 to 1000 pM (R2 = 0.9984), with a limit of detection (LOD) of 0.21 pM and a limit of quantification (LOQ) of 0.70 pM. The neutral-backbone PNA probe improved hybridization kinetics and selectivity.
Conclusions:
The PNA/GNH - AuNP interface enabled fast, stable, and highly sensitive E. coli detection. Its disposable electrode format and portable electrochemical readout make it suitable for on-site diagnostic and food-safety monitoring applications.
