Nanostructured metal oxides, especially zinc oxide, ZnO had attracted great attention for the construction of biosensor due to its high isoelectric point (IEC). This high IEP of ZnO made it a good material for immobilisation of DNA through electrostatic interaction. On the other hand, the good conductivity, large surface area and biocompatibility have made carbon based materials such as reduced graphene oxide, rGO  suitable candidate for electrochemical biosensor. In addition, rGO is an unique materials which has the ability to accept the electrons from the photocatalyst, ZnO and to slow down the recombination rate of electron-hole of ZnO. The limitation of ZnO as photocatalyts can be overcomed by forming hybrid with rGO. Thus, we used the rGO-ZnO thin film  for biosensing and as photocatalyst for photoinactivation for bacteria in water. In this paper, reduced graphene oxide (rGO) was utilised to form hybrid with zinc oxide (ZnO) by electrodeposition. This rGO-ZnO thin film electrode acted as a hybrid-platform both for electrochemical and photoelectrochemical biosensor for the detection of S.Typhi in water. After biosensing, the same rGO-ZnO thin film, as photocatalyts too, was used to accelerate the sunlight-mediated inactivation of S.Typhi in the water sample.

Acknowledgement

This research is supported by University Malaya Flagship Grant project FL001A-14AET, and Transdisciplinary Research Grant Scheme (TRGS TR002A-2014) from Malaysian Ministry of Higher Education.