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Here we report successful demonstration of a FET-like electrochemical nano-biosensor to accurately detect ultralow concentrations of adenosine triphosphate. As a 2D material, graphene is a promising candidate due to its large surface area, biocompatibility, and demonstrated surface binding chemistries and has been employed as the conducting channel. A short 20-base DNA aptamer is used as the sensing element to ensure that the interaction between the analyte and the aptamer occurs within the Debye length of the electrolyte (PBS). Significant increase in the drain current with progressive addition of ATP is observed whereas for control experiments, no distinct change in the drain current occurs. The sensor is found to be highly sensitive in the nanomolar (nM) to micromolar ( μM) range with a high sensitivity of 2.55 μA (mM) (-1), a detection limit as low as 10 pM, and it has potential application in medical and biological settings to detect low traces of ATP. This simplistic design strategy can be further extended to efficiently detect a broad range of other target analytes.

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Fe-based modified activated carbon prepared by impregnation was used for adsorbents in Hg 0 purification.The influence of carriers, active components, FeCl 3 solution concentration and calcination temperature, were investigated for Hg 0 adsorption purification. The effects of the preparation conditions on the adsorbent were characterized by N 2 adsorption-desorption isotherms, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and (FTIR). The samples modified with FeCl 3 showed an obvious performance for Hg 0 removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg 0 ) into its oxidized form (Hg 2+ ). The mechanisms of mercury adsorption onto the Cl-impregnated activated carbon were proposed. The optimal conditions for adsorptive purification are an Fe 3+ concentration of 0.15 mol L À1 , calcination temperature of 300 C at an adsorption temperature of 40 C and carrier gas flow rate of 300 mL min À1 .