Paper-Based Electrodes Conjugated with Tungsten Disulfide Nanostructure and Aptamer for Impedimetric Detection of Listeria monocytogenes

In this study, we report on a novel aptasensor based on an electrochemical paper-based analytical device (ePAD) that employs a tungsten disulfide (WS2)/aptamer hybrid for the detection of Listeria monocytogenes. Listeria is a well-known causative pathogen for foodborne diseases. The proposed aptasensor signifies many lucrative features which include simple, cost-effective, reliable, and disposable. Furthermore, the use of an aptamer added more advantageous features in the biosensor. The morphological, optical, elemental composition, and phase properties of the synthesized tungsten disulfide (WS2) nanostructures were characterized by field-emission scanning electron microscopy (FESEM), RAMAN spectroscopy, photoluminescence (PL), and X-ray diffraction (XRD), while electrochemical impedance spectroscopy was performed to corroborate the immobilization of aptamer and to assess the L. monocytogenes sensing performance. The limit of detection (LoD) and limit of quantification (LoQ) of the aptasensor was found to be 10 and 4.5 CFU/mL, respectively, within a linear range of 10(1)-10(8) CFU/mL. The proposed sensor was found to be selective solely towards Listeria monocytogenes in the presence of various bacterial species such as Escherichia coli and Bacillus subtilis. Validation of the aptasensor operation was also evaluated in real samples by spiking them with fixed concentrations (10(1), 10(3), and 10(5)) of Listeria monocytogenes, thereby, paving the way for its potential in a point-of-care scenario.