Tin disulfide nanorod-graphene-ß-cyclodextrin nanocomposites for sensing dopamine in rat brains and human blood serum.

In the present work describes a facile synthesis of tin disulfide (SnS2) nanorods decorated graphene-ß-cyclodextrin (SnS2/GR-ß-CD) nanocomposite for robust and novel dopamine (DA) electrochemical biosensor applications. The DA biosensor was fabricated using the glassy carbon electrode (GCE) modified with SnS2/GR-ß-CD nanocomposite. The sonochemical and hydrothermal methods have been used for the synthesis of SnS2/GR-ß-CD. Different physicochemical methods were used to confirm the formation of the GR-ß-CD, SnS2, and SnS2/GR-ß-CD nanocomposite. The cyclicvoltammetric cathodic current response of DA was 5 folds higher than those observed at bare, ß-CD, SnS2-ß-CD, and GR-ß-CD modified GCEs. Under optimised conditions, the biosensor's DPV response current is linear to DA from the concentration of 0.01-150.76 µM. The detection limit of the biosensor was 4 nM. The SnS2/GR-ß-CD biosensor shows an excellent selectivity towards DA in the presence of common interfering species, including ascorbic acid and uric acid. Also, the as-prepared nanocomposite-modified electrode exhibited satisfactory long-term stability, sensitivity (2.49 µAµM-1 cm-2) along with reusability for detection of DA. The fabricated SnS2/GR-ß-CD biosensor was successfully used for the detection of DA in the rat brain and human blood serum samples.

Sonochemical synthesis of gum guar biopolymer stabilized copper oxide on exfoliated graphite: Application for enhanced electrochemical detection of H2O2 in milk and pharmaceutical samples.

A novel and cost-effective synthesis of biopolymer-based organic and inorganic composite materials have received substantial attention in a broad range application including electroanalysis of small molecules. In this perspective, we report the synthesis of gum guar (guar) biopolymer stabilized cupric oxide decorated on exfoliated graphite (GR-guar/CuO) composite. Different physicochemical characterization methods were used to confirm the successful exfoliation of graphite and formation of the GR-guar/CuO composite. A simple sonochemical method has been used for the preparation of guar stabilized exfoliated graphite (GR-guar). The flower-like CuO on GR-guar and guar stabilized CuO (CuO-guar) composites were synthesized using a hydrothermal method. Cyclic voltammetric studies revealed that the GR-guar/CuO composite modified screen-printed carbon electrode (SPCE) had enhanced electro-reduction ability towards H2O2 than GR-guar and pristine graphite/CuO-guar modified SPCEs. Under optimized experimental conditions, the GR-guar/CuO composite modified electrode detects H2O2 in the response ranges from 0.02 to 1296.6 µM. The sensor shows a lower detection limit of 5.8 nM with high sensitivity. The as-prepared GR-guar/CuO composite sensor is highly reproducible and had excellent selectivity and practicality towards the detection of H2O2. Consequently, the fabricated sensor can be used for the accurate detection of H2O2 in real samples.

Facile synthesis of cellulose microfibers supported palladium nanospindles on graphene oxide for selective detection of dopamine in pharmaceutical and biological samples.

The cost-effective synthesis of novel functional nanomaterials has received significant attention in the physical and chemical sciences due to their improved surface area, high catalytic activity along with unique morphological features. This paper reports a facile and eco-friendly synthesis of spindle-like palladium nanostructures (PdSPs) on graphene oxide-cellulose microfiber (GO-CMF) composite for the first time. The GO-CMF/PdSPs composite was synthesized by an electrochemical method without the use of additional surfactants and capping agents. The synthesized materials were characterized and confirmed by using transmission electron microscopy, high-resolution scanning electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy and Fourier-transform infrared spectroscopy. As-synthesized GO-CMF/PdSPs composite modified electrode was used as a selective electrocatalyst for the oxidation of dopamine (DA). The electrochemical redox behaviors of DA were investigated using cyclic voltammetry (CV). The CV results revealed that the GO-CMF/PdSPs composite modified electrode has 10 folds enhanced oxidation current response to DA than GO, PdSPs and GO-CMF modified GCEs. Under optimized conditions, the GO-CMF/PdSPs composite sensor exhibits a linear response to DA in the concentration range from 0.3 to 196.3 µM with the lower detection limit of 23 nM. The nanocomposite electrode also shows promising features towards the reliable and selective detection of DA, which includes high stability, reproducibility and high selectivity towards the commonly interfering species such as ascorbic acid, uric acid, and dihydroxybenzene isomers. The sensor was successfully tested for the real-time detection of DA in the commercial DA injections and human serum samples.