Graphene Oxide as a Novel Signal Enhancer for Cell-Based Impedimetric Biosensors

Abstract

Electrical cell-based biosensors that use microelectrodes as singal transducers have been extensively used in various bio-related studies. A number of methods are available for increasing the biocompatibility of transducers to promote the biological conditions for mammalian cell adhesion and proliferation. Mimicking the extracellular matrix microenvironment using collagen or fibronectin-coated electrodes is one of the most favorable methods; however, high cost and unwanted signal have been identified as common disadvantages of these materials. Here, we introduce graphene oxide as an alternative and effective material for electrode modification. Graphene oxide nanosheets provide oxygen-containing groups and a rough surface, allowing spontaneous adsorption of proteins via a combination of interactions, intensifying cell binding and cell growth. The cellular impedance signal is accordingly more sensitive. In brief, an appropriate amount of graphene oxide, determined to be non-toxic was immobilized onto the surface of a gold electrode via pi-pi stacking interactions between the arene units of functionalized mercaptoarenes and graphene oxide nanosheets. After 6 h, graphene oxide was shown to remarkably enhance the attachment of A549 cells, based on both cellular morphology and impedimetric analyses. After 24 h, the cellular impedance signal was 1.31 times higher than when using a bare gold electrode. This study provides insight into the biological properties of graphene oxide and its potential applications in cell-based biosensor development.