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We report on the adsorption dynamics of phospholipid membranes on graphene-coated substrates using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. We compare the lipid vescle interaction and membranne formation on gold and silicon dioxide QCM crystal surfaces with their graphene oxide (GO) and reduced (r)GO coated counterparts, and report on the different lipid structures obtained. We establish graphene derivative coatings as support surfaces with tuneable hydrophobicity for the formation of controllable lipid structures. One structure of interest formed are lipid monolayer membrannes which were formed on rGO, which are otherwise challenging to produce. We also demonstrate and monitor biotin-avidin binding on such a membranne, which will then serve as a platform for a wide range of biosensing applications. The QCM-D technique could be extended to both fundamental studies and applications of other covalent and non-covalent interactions in 2-dimensional materials. [7], [8]. Graphene derivatives can solubilize and bind drug molecules and thus have the potential to be drug delivery vehicles [9]. Such properties can be exploited to increase the sensitivity of biosensors [10] and may act as a supporting platform for the construction of biological detection arrays [11], [12]. Graphene oxide (GO) has played an important role in the development of electrochemical [10], [13] and mass-sensitive sensors [14], [15] and inclusively it has shown strong antibacterial activity [16] by affecting the integrity of the cell membrane [17], which is formed by a continuous lipid bilayer. In GO, the main surface functional groups are hydroxyls and epoxies [18], with carboxylic acids and other keto groups on the edges [19]. GO retains sp 2 -carbon domains as well as sp 3 -carbon groups, endowing it with both hydrophobic and hydrophilic domains, respectively [20]. A majority of such functional groups can be removed upon treatment with a reducing agent, such as L-ascorbic acid [21] or hydrazine [22], or thermally [23] to form reduced (r)GO, which is overall significantly more hydrophobic, comparable to pristine graphene. Exploring different routes for the construction of supported lipid membranes (SLMs) (Scheme 1a), such as supported lipid bilayers (SLBs) or monolayers is pertinent since they are useful platforms for the study of fundamental cell functions and signaling, cell-cell interactions, drug delivery and biosensing [24]. SLMs help to establish a model for the cell membrane and can serve as the key component of biosensor devices. The most common membrane lipids are phospholipids; amphiphilic molecules composed of hydrocarbon chain tails attached to a phosphate head group.Here we present the study of the adsorption and rupture of small unilamellar vesicles (SUVs) (typically <100 nm) on GO-and rGOsubstrates, monitored using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique [25]. Substrates used here were produced by spin coating GO on QCM-D crystals. This coating technique i...

We present a sensitive and low-cost immunoassay, based on a customized open-source quartz crystal microbalance coupled with graphene biointerface sensors (G-QCM), to quantify antibodies in undiluted patient serum. We demonstrate its efficacy for a specific antibody against the phospholipase A2 receptor (anti-PLA2R), which is a biomarker in primary membranous nephropathy. A novel graphene–protein biointerface was constructed by adsorbing a low concentration of denatured bovine serum albumin (dBSA) on the reduced graphene oxide (rGO) sensor surface. The dBSA film prevents the denaturation of the protein receptor on the rGO surface and serves as the cross-linker for immobilization of the receptor for anti-PLA2R antibodies on the surface. The detection limit and selectivity of this G-QCM biosensor was compared with a commercial QCM system. The G-QCM immunoassay exhibited good specificity and high sensitivity toward the target, with an order of magnitude better detection limit (of 100 ng/mL) compared to the commercial system, at a fraction of the cost and with considerable time saving. The results obtained from patient sera compared favorably with those from enzyme-linked immunosorbent assay, validating the feasibility of use in clinical applications. The multifunctional dBSA-rGO platform provides a promising biofunctionalization method for universal immunoassay and biosensors. With the advantages of inexpensive, rapid, and sensitive detection, the G-QCM sensor and instrument form an effective autoimmune disease screening tool.