Listeria monocytogenes (LM) is one of the deadliest and most hazardous pathogens, posing extremely serious harm to the human health, hence developing simple and effective method for its highly sensitive detection is very important. In this work, by preparing Pt nanoparticles/hollow carbon spheres (Pt/HCNs) nanohybrid as nano-zyme, a simple and highly sensitive nanozyme-based electrochemical sensor was developed for the first time to detect LM based on aptamer (Apt)-regulated Pt/HCNs nanozyme activity. The as-prepared Pt/HCNs nanozyme can catalyze the oxidation of o-phenylenediamine to generate electroactive 2,3-diaminophenazinc (DAP) which offers an obvious reduction peak current. However, once bound to LM-Apt to form Apt/Pt/HCNs, the related enzyme-like activity of Pt/HCNs is inhibited remarkably and the reduction current of DAP nearly disappear owing to the covering of the active sites. Interestingly, in the presence of LM, the nanozyme activity can be recovered through the specific recognition of Apt towards LM. After optimizing various conditions, the designed Apt-regulated nanozyme-based electrochemical sensor shows excellent sensing performances for LM. Meanwhile, the designed sensors exhibits superior selectivity, specificity, reproducibility, stability and real applications. This work offers a simple and novel strategy for the effective and highly sensitive determination of various pathogens via altering simply the specific Apt.

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As one of the most hazardous and deadliest pathogens, Listeria monocytogenes (LM) posed various serious diseases to the human being, thus designing effective strategy for its detection is of great significance. In this work, by preparing Ti3C2Tx MXenes nanoribbon (Ti3C2TxR) as carrier and selecting thionine (Th) acted simultaneously as signal probe and functional monomer, a LM pathogen-imprinted polymers (PIP) integrated probe electrochemical sensor was design to monitor LM for the first time, that was carried out through the electropolymerization of Th on the Ti3C2TxR/GCE surface in the existence of LM. Upon eluting the templates from the LM imprinted cavities, the fabricated PIP/Ti3C2TxR/GCE sensor can rebound LM cells effectively. By recording the peak current of Th as the response signal, it can be weakened when LM cell was re-bound to the LM imprinted cavity on PIP/Ti3C2TxR/GCE, and the absolute values of peak current change increase with the increasement of LM concentrations. After optimizing three key parameters, a considerable low analytical limit (2 CFU mL−1) and wide linearity (10–108 CFU mL−1) for LM were achieved. In addition, the experiments demonstrated that the PIP/Ti3C2TxR sensor offers satisfactory selectivity, reproducibility and stability.

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 - 10_4-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.