ABSTRACT
Biomedical applications such as cell screening or cell-cell interaction studies require placement and adhesion of cells on surfaces with controlled numbers and location. In particular, single-cell arraying and positioning has come into focus as a basis of such applications. An ideal substrate would combine biocompatibility with favorable attributes such as pattern stability and easy processing. Here, we present a simple yet effective approach to single-cell arraying based on a graphene oxide (GO) surface carrying protein (fibronectin) microarrays to define cell adhesion points. These capture NIH-3T3 cells, resulting in cell arrays, which are benchmarked against analogous arrays on silanized glass samples. We reveal significant improvement in cell-capture performance by the GO coating with regards to overall cell adhesion and single-cell feature occupancy. This overall improvement of cell-arraying combined with retained transparency of substrate for microscopy and good biocompatibility makes this graphene-based approach attractive for single-cell experiments.
Subject(s)
Graphite , Animals , Cell Adhesion , Glass , Mice , NIH 3T3 CellsABSTRACT
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.
Subject(s)
Biosensing Techniques , Graphite , Humans , Immunoassay , Point-of-Care Systems , Quartz Crystal Microbalance TechniquesABSTRACT
The development of compressible supercapacitor highly relies on the innovative design of electrode materials with both superior compression property and high capacitive performance. This work reports a highly compressible supercapacitor electrode which is prepared by growing electroactive NiCo2S4 (NCS) nanosheets on the compressible carbon sponge (CS). The strong adhesion of the metallic conductive NCS nanosheets to the highly porous carbon scaffolds enable the CS-NCS composite electrode to exhibit an enhanced conductivity and ideal structural integrity during repeated compression-release cycles. Accordingly, the CS-NCS composite electrode delivers a specific capacitance of 1093 F g-1 at 0.5 A g-1 and remarkable rate performance with 91% capacitance retention in the range of 0.5-20 A g-1. Capacitance performance under the strain of 60% shows that the incorporation of NCS nanosheets in CS scaffolds leads to over five times enhancement in gravimetric capacitance and 17 times enhancement in volumetric capacitance. These performances enable the CS-NCS composite to be one of the promising candidates for potential applications in compressible electrochemical energy storage devices.
