Metal/Metal Oxide Modified Graphene Nanostructures for Electrical Biosensing Applications: A Review

Tremendous accomplishments have been made in the field of metal/metal oxide modified graphene nanostructures to overcome the problems of agglomeration and restacking in graphene biosensors. Some review articles are available on electrochemical biosensing applications of graphene based composites and hybrids. However, none of them have made significant contributions in their applications in the domain of field effect transistor (FET) and impedance biosensors. In this manuscript, the authors analytically summarize not only the state-of-the art electrochemical biosensors using metal/metal oxide modified graphene but also a detailed discussion on FET and impedance-based biosensors has been presented along with the comprehensive physics behind enhanced sensing performance of such devices. It has been observed that sub-femtomolar detection limits are achievable using FET and impedance based label free sensing which has been attributed to the metal nanoparticle induced modulation in band gap. Moreover, the technological advancements in the synthesis techniques based on encapsulation of various metal nanoforms onto electrochemically activated graphene to initiate more reactive sites on the graphene surface have been thoroughly compiled. Despite these advances, the use of graphene-based hybrid nanostructures for biosensors is still in its early stages and we have highlighted the existing challenges and indicated the future research direction.