Quartz crystal microbalance technique for studies of adsorption and binding dynamics on graphene platforms

The interaction between zwitterionic lipids and graphene derivatives, such as graphene oxide (GO) and thermally reduced graphene oxide (rGO), was investigated using the quartz crystal microbalance with dissipation monitoring (QCM-D), a technique with high time resolution that offers an ultra-low mass detection range. Graphene-based QCM sensors were developed using an effective route for thin film deposition of graphene dispersion where additional low-temperature thermal reduction was used to obtain rGO coatings. The overall study showed that this is a novel application of graphene derivatives on QCM systems targeted at biomolecular detections. It was corroborated that the hydrophobic degree of the supports plays a pivotal role in the adsorption dynamics and graphene emerges as a platform with tunable hydrophobicity. Lipid monolayers were obtained on rGO-coated QCM sensors while small unilamellar vesicles stayed unruptured jointly with bicelle-like structures to form a mixed lipid layer on GO-coated sensors. The effectiveness of the obtained supported lipid layers was demonstrated through the assay of a binding event of high specificity, as that of the biotin-avidin complex. In addition, an integrated QCM laboratory was developed and evaluated based on a commercially available and low-cost open-source QCM device.