Determination of sulfate-reducing bacteria with chemical conversion from ZnO nanorods arrays to ZnS arrays

This work presents a novel specific detection method for sulfate-reducing bacteria (SRB) based on sulfuration conversion from ZnO arrays to ZnS arrays. The sulfuration process was conducted in two steps. First, ZnO@ZnS intermediate nanocomposite arrays were formed by the sulfuration reaction between ZnO and sulfide, which is the characteristic enzymatic metabolism product of SRB. Next, unconverted ZnO cores were washed away in ammonia buffer solutions, leaving ZnS arrays on the surface of ITO substrates. The array conversion process can be used for SRB detection because the final state of ZnS arrays was highly related with the amount of accumulated sulfide, which was decided by the initial concentration of SRB. Electrochemical impedance spectroscopy has been used to optimize experimental conditions and detect SRB in aqueous solutions. This SRB detection method based on arrays conversion from ZnO to ZnS can avoid the use of biological recognition elements, which are expensive and easy to lose specific recognizing abilities. In addition, compared with the widely used MPN method which would take up to 15 days to accomplish the detection process, the proposed method can shorten the detection time greatly.