A DNA biosensor for molecular diagnosis of <i>Aeromonas hydrophila</i> using zinc sulfide nanospheres

Abstract

Abstract. Today, identification of pathogenic bacteria using modern and accurate methods is inevitable. Integration in electrochemical measurements with nanotechnology has led to the design of efficient and sensitive DNA biosensors against bacterial agents. Here, efforts were made to detect Aeromonas hydrophila using aptamers as probes and zinc sulfide (ZnS) nanospheres as signal enhancers and electron transfer facilitators. After modification of the working electrode area (in a screen-printed electrode) with ZnS nanospheres through electrodeposition, the coated surface of a modified electrode with ZnS nanospheres was investigated through scanning electron microscopy (SEM). The size of synthesized ZnS nanospheres was estimated at about 20-50 nm and their shape was in the form of porous plates in microscopic observations. All electrochemical measurements were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and constant potential amperometry (CPA) techniques. The designed DNA biosensor was able to detect deoxyribonucleic acid (DNA) of Aeromonas hydrophila in the range 1.0 × 10 −4 to 1.0 × 10 −9 mol L −1 ; the limit of detection (LOD) in this study was 1 × 10 −13 mol L −1 . This DNA biosensor showed satisfactory thermal and pH stability. Reproducibility for this DNA biosensor was measured and the relative standard deviation (RSD) of the performance of this DNA biosensor was calculated as 5 % during 42 days.