A Novel Nanostructure-based Genosensor for Detection of Shigella dysenteriae in Human Plasma Samples by Porous MoS۲ Nanosheets and Au Nanoparticles

Shigella dysenteriae (S. dysenteriae) is a species of the rod-shaped bacterial genus Shigella. Shigella species can cause shigellosis (bacillary dysentery). The most commonly observed signs associated with Shigella dysentery include colitis, malnutrition, rectal prolapse, tenesmus, reactive arthritis, and central nervous system problems. Further, S. dysenteriae is associated with the development of hemolytic-uremic syndrome, which includes anemia, thrombocytopenia, and kidney failure. If infected with S. dysenteriae, an individual will experience a severe case of shigellosis. Most cases of shigellosis are in developing countries. Shigellosis outbreaks in Asia, Latin America and Africa have had mortality rates of up to ۲۰%. Due to negative effects of the S. dysenteriae in human health, highly-sensitive determination of this pathogenic agents is of great importance. In this study, electrochemical oligonucleotide genosensor based on DNA hybridization process was developed to detect Shigella dysenteriae in human plasma samples. The porous MoS۲ nanosheets were initially casted on the electrode. Then, Au nanoparticles (AuNPs) was electro-deposited on the electrode surface. The obtained modifier agent was effectively used for electrochemical analysis of the bio-assay. Various electrochemical techniques including cyclic voltammetry (CV) and Differential pulse anodic stripping voltammetry (DPASV) have been used to investigate the applicability of the fabricated genosensing bio-assay. Under optimal conditions, LOD were calculated ۹.۱۴ fM. In addition, a wide linear range was obtained. The fabricated bio-detection assay indicated high selectivity for ۱, ۲, and ۳ base mismatch sequences and also high recovery indexes in human plasma samples. In addition, a negative control of the biosensing platform was provided. The obtained results confirmed that the biosensor possess high selectivity. Moreover, the RSD% (relative standard deviation) was below ۵ which indicated the high accuracy and repeatability of the sensing assay.