Simple Label-Free DNA Sensor Based on CeO2 Nanorods Decorated with Ppy Nanoparticles

Abstract

A facile label-free DNA sensor based on cerium oxide nanorods decorated with polypyrrole nanoparticles (CeO2-NRs/Ppy-NPs) matrix has been developed for detection of Salmonella. The sensor was fabricated by hydrothermal synthesis of CeO2-NRs on the microelectrode surface followed by in situ chemical oxidative polymerization of pyrrole on the CeO2-NRs to prepare a CeO2-NR/Ppy-NPs electrode. Single-stranded DNA (ssDNA) sequences were immobilized onto the modified microelectrode by covalent attachment. The properties of the material were explored by field-emission scanning electron microscopy, x-ray diffraction analysis, and Fourier-transform infrared spectroscopy techniques. The response of the DNA biosensor was investigated by electrochemical impedance spectroscopy with [Fe(CN)6]3−/4− as redox probe. The results showed that the response of the DNA biosensor exhibited good linearity within the range of 1.0 × 10−9 mol L−1 to 1.0 × 10−6 mol L−1 with sensitivity of 14.7 × 106 Ω/mol L−1 cm−1. The limit of detection and limit of quantification of the DNA biosensor were low, with values of 2.86.10−7 mol L−1 and 9.56.10−7 mol L−1, respectively.