The electrocatalytic properties of the redox couple Ni(OH) 2 /NiOOH at physiological pH was investigated in the presence of cationic polymeric films providing alkaline microenvironments, with the objective of developing a biosensor for cholesterol and glucose. The Ni(OH) 2 /NiOOH modified electrodes in presence of the cationic polymer overlayers were well characterized by optical and electrochemical techniques. The modified electrodes showed excellent catalytic properties toward hydrogen peroxide oxidation and exhibited a wide linear range compared to the conventional and expensive Pt based catalysts used in H 2 O 2 based sensors. The superb electrocatalysis of hydrogen peroxide could be combined with the enzymatic oxidation of cholesterol and glucose showing, the feasibility of monitoring biological metabolites like glucose and cholesterol using the basic catalyst Ni(OH) 2 /NiOOH at physiological pH. Modified electrodes were highly stable and yielded reproducible results. Further the influence of graphene layer in decreasing the overpotential of the detection of H 2 O 2 and its effect on the biosensing of cholesterol and glucose was further investigated. The sensing protocol was validated in the analysis of blood sugar in serum samples.

Delaminated 2D sheets of MoSe were prepared by liquid phase exfoliation and were embedded over high surface area hydrogen exfoliated graphene (HEG) by a simple technique. The MoSe/HEG hybrid composite exhibits fast heterogeneous electron-transfer (HET) and a high electrochemically active surface area compared to only HEG. When employed for detection of NADH, it exhibits electrooxidation at a low potential of 150 mV (vs. Ag/AgCl) with high sensitivity of 0.0814 µA⋅µM⋅cm over a wide linear range (1-280 μM), good selectivity, and a low limit of detection (1 μM). The good performance of the composite is due to the homogeneously dispersed 2D sheets of MoSe over large-surface area HEG, which retain its electrochemical activity, prevents restacking, and acts as an electron transfer channel. On the basis of the above analytical requirements and its easy synthesis, the hybrid composite represents a robust material for electrochemical sensing. Graphical abstract Schematic of the 2D MoSe/HEG composite for electrochemical detection of NADH.

Metal/metaloxide based composite materials have wide spread applications in electrochemical sensors and fuel cell applications. Hence, the present work is directed towards the fabrication of cost effective and highly sensitive electrode material for cysteine sensing. In this work, Co-Gd 2 O 3 nanocomposite is prepared by a simple electrodeposition route and used as electrochemical sensor material. The prepared nanocomposite materials are characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Xray Diffraction spectroscopy (XRD), Energy dispersive X-ray spectroscopy (EDX), and X-ray Photo electron spectroscopy (XPS). SEM images exhibited as hierarchical nanoflakes with open porous structure. EDX analysis showed the presence of cobalt and gadolinium. The reflections at 2q = 33 0 and 35.7 0 corresponds to the cubic structured Gd 2 O 3 nanoparticles validated the formation of nanocomposite. Electrooxidation of L-cysteine on Co and Co-Gd 2 O 3 was carried out using cyclic voltammetry technique. Upon addition of certain concentration of cysteine, the anodic peak current get increased with the simultaneous decline in the cathodic peak currents displayed the excellent electrocatalytic activity of Co-Gd 2 O 3 nanocomposite. The chronoamperometric experiments were performed to derive the analytical parameters like sensitivity, limit of detection and linear range. The reproducibility, stability and real sample analysis was studied using chronoamperometry.[a] S. Premlatha

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Co-crystals of L-phenylalanine hydrochloride (LPAHCl) were grown by slow evaporation technique in the presence of manganese sulphate and cadmium chloride. Crystallinity of the grown crystals was confirmed by single crystal X-ray diffraction. Optical transmission spectra showed very high transmittance in the entire visible region. The cut-off wavelength was observed at 250 nm for both the crystals. The optical band gap energy was found to be 4.37 eV and 4.31 eV for the grown co-crystals of LPAHCl with MnSO 4 and CdCl 2 , respectively. The second harmonic generation of the grown crystals was confirmed by Kurtz and Perry powder SHG method and compared with KDP. The frequency dependent dielectric properties of the co-crystals were studied at different temperatures.