Liposome functionalized reduced graphene oxide for rapid electrochemical sensing of bacteria

Pathogenic bacteria represent a severe threat to global public health, particularly with the growing rate of antibiotic resistance, and, therefore, indicate a critical need for developing efficient sensing platforms. Liposome-based sensors are collocating interest due to their intrinsic fusogenic ability to fuse with the outer membrane of bacteria. However, the lack of a conducting property limits their applicability for developing biosensing platforms. In this study, we report conjugation of liposomes with reduced graphene oxide (rGO) for fabricating a rapid and sensitive biosensor for electrochemical detection of Escherichia coli (E. coli). The large surface area of rGO facilitated binding of liposomes with their surface, and the intrinsic electrical and biocompatible properties assisted electrochemical sensing of bacteria. The electrochemical response of the liposome and the rGO-liposome coated electrode shows nonconducting and conducting characteristics, respectively. A significant change in the peak current of differential pulse voltammetry with the gradual variation of bacterial density in the electrolyte was observed for the glassy carbon electrode rGO-liposome (GCE-L-rGO) surface only. The detection sensitivity of GCE-L-rGO sensors was ∼26 μA/106 cells per ml of electrolyte for varying cell densities from 3 × 103 to 3 × 104 cells/ml. The proposed sensing technique can serve as an alternative to conventional methodologies for rapid and in situ detection of bacterial load in different samples, laying the foundation for new applications in clinical diagnostics.