Functionalized MoS2 nanosheets assembled microfluidic immunosensor for highly sensitive detection of food pathogen

Two dimensional nanomaterials such as molybdenum disulfide (MoS2) has gained significant interest in designing electrochemical devices for biosensing application. In this work, we have designed cetyltrimethyl ammonium bromide (CTAB) functionalized MoS2 nanosheets (CTAB-MoS2-NS) for conjugation of protein on the microfluidics electrode for Salmonella typhimurium (S.typhimurium) detection. MoS2 nanosheets from the bulk MoS2 were synthesized using CTAB assisted exfoliation methods resulting into positive charge on the CTAB-MoS2-NS. Further, optical and electron microscopic studies of CTAB-MoS2-NS reveal, its suitability for biosensing application. These CTAB-MoS2-NS were deposited onto the patterned hydrolyzed indium tin oxide (ITO) microelelctrode, utilizing the strong electrostatic interaction with the positively charged CTAB-MoS2-NS. Then microelectrode has been integrated with polydimethylsiloxane (PDMS) microfluidic device to design a Lab on a Chip platform for S.typhimurium detection. Detection of the S.typhimurium cells have been performed using electrochemical impedance spectroscopy (EIS) technique. The fabricated microfluidic immunosensor offers highly improved biosensing parameters, as sensitivity was found to be 1.79 kΩ/CFU−1 mL cm−2 with the detection limit 1.56 CFU mL−1in the wide detection range of 101–107 CFUmL−1.