Highly Sensitive Electrochemical Immunosensing for Listeria Monocytogenes Based on 3,4,9,10-Perylene Tetracarboxylic Acid/Graphene Ribbons as a Sensing Platform and Ferrocene/Gold Nanoparticles as an Amplifier

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As a gram-positive foodborne pathogen, Listeria monocytogenes (LM) can cause many serious diseases to the human health coupled with high mortality rates; thus, constructing an effective method to detect LM is of great significance. Herein, a novel sandwich-type electrochemical immunosensor is proposed for LM by introducing 3,4,9,10-perylene tetracarboxylic acid/graphene ribbons (PTCA/GNR) nanohybrids as a sensing platform and ferrocene/gold nanoparticles (Fc/Au NPs) as a signal amplifier. The high conductivity and large surface area of GNR can increase the immobilizing amount of the primary antibody (PAb) and enhance the electron transport rate, while Au NPs can carry secondary antibodies (SAb) and Fc derivative (Fc-SH) to form a SAb-Au NPs-Fc signal amplifier. Through using Fc molecules as a signal probe, its peak current can appear and increase varied from the LM concentrations; hence, a highly sensitive sandwich-type immunosensor was constructed wide linear range from 10 to 2 × 10⁴-CFU mL⁻¹ and low limit of detection of low to 6 CFU mL⁻¹. Furthermore, the specificity of the immunosensor was also studied and a satisfactory result was obtained.