Graphene-coated soft elastic substrates for cell adhesion studies: Local nanomechanics and label-free electronic biosensing

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Cell culture has long been performed in plates where the stiff underlying substrate has only served as a support. Recent observations have shown that cells interact with their microenvironment and the stiffness of the underlying surface plays an active role in cell growth and proliferation. Varying the stiffness of substrates for cell growth provides a versatile handle to modulate the mechanical properties of the local cellular microenvironment and study the effect on cell-cell and cell-surface interactions. Most of the investigations on studying cell adhesion on soft elastic substrates utilize optical detection methods where labeling is often necessary and the possibility to obtain real-time information at the interfacial level is limited. Electronic readout of cell-substrate interactions by suitable electrodes placed between the cells and the growth substrate will allow the possibility to study cell adhesion in real-time in a label-free manner. Here we propose the realization of a biomaterial platform wherein soft elastic substrates are coated with a single sheet of graphene as electrode material for studying cell adhesion. Three specific aspects will be investigated in this proposal using this platform. First, the project aims at obtaining an improved understanding of the effect of single graphene sheets on the stiffness of elastic substrates by using dynamic nanomechanical scanning probe microscopy. A second principal goal is the realization of sensing devices based on the graphene sheet on soft substrates and utilize impedance detection to study cellular processes in real time. Finally, we will exploit chemical functionalization of graphene to provide suitable receptors at the interface and study the ensuing effect on cell behavior. Although the proposed activities will focus mainly on breast cancer cells, this unique sensing platform can be extended to other cell types and cellular processes.