We recently reported a simple and cost-effective green method to produce free-standing, flexible, and highly conductive electrochemically exfoliated graphene paper (GrP) for a supercapacitor application. To improve the capacitance behavior of GrP, manganese dioxide (MnO2) was electrochemically deposited on GrP with different number of MnO2 cycles. After the electrochemical deposition process, MnO2 nanoflowers were formed, which provide a fast transfer of electrolyte ions. After 10 cycles of electrodeposition, MnO2-coated GrP (GrP/10-MnO2, which is the optimal composition) exhibited an excellent capacitive performance with a high specific capacitance of 385.2 F·g–1 at 1 mV·s–1 in 0.1 M Na2SO4 electrolyte and outstanding capacitance retention after 5000 consecutive cycles. Taking advantage of both superior mechanical and capacitance behavior of GrP and GrP/10-MnO2 electrodes, a flexible solid-state asymmetric supercapacitor (SASc) device was assembled using GrP/10-MnO2 and GrP as positive and negative electrode, respectively. The fabricated SASc device exhibited not only high areal capacitances of 76.8 mF cm–2 at a current density of 0.05 mA cm–2 but also excellent cycling stability of 82.2% after 5000 consecutive galvanostatic charge/discharge cycles. This flexible supercapacitor can also deliver a high energy density of 6.14 mWh·cm–2 with a power density of 36 mW·cm–2. This research represents a new direction for exploring the potential of free-standing GrP and its nanocomposites in flexible energy-storage systems.

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We report the development of an antibody (anti-MC1R antibody)-functionalized polyaniline nanofibers modified screen-printed electrode capable of efficient electrochemical detection of melanoma cells at levels (1 cell per mL) not readily achieved by other methods. This immunosensor is highly selective in its detection of melanoma cells over normal human cells.

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A rapid and simple approach for visible determination of mercury ions (Hg(2+) ) in aqueous solutions was developed based on surface plasmon resonance phenomenon using L-arginine-functionalized gold nanorods (AuNRs). At pH greater than 9, the deprotonated amine group of L-arginine on the AuNRs bound with Hg(2+) leading to the side-by-side assembly of AuNRs, which was verified by transmission electron microscopy images. Thus, when Hg(2+) was present in the test solution, a blue shift of the typical longitudinal plasmon band of the AuNRs was observed in the ultra violet-visible-near infrared (UV-Vis-NIR) spectra, along with a change in the color of the solution, which occurred within 5 min. After carefully optimizing the potential factors affecting the performance, the L-arginine/AuNRs sensing system was found to be highly sensitive to Hg(2+) , with the limit of detection of 5 nM (S/N = 3); it is also very selective and free of interference from 10 other metal ions (Ba(2+) , Ca(2+) , Cd(2+) , Co(2+) , Cs(+) , Cu(2+) , K(+) , Li(+) , Ni(2+) , Pb(2+) ). The result suggests that the L-arginine-functionalized AuNRs can potentially serve as a rapid, sensitive, and easy-to-use colorimetric biosensor useful for determining Hg(2+) in food and environmental samples.