Designing an electrochemical sensor which is simple, cheap, sensitive, fast, and accurate is inevitable, as it is important in drug quality control, point-of-care diagnosis, and other clinical studies. Sensors for simultaneous determination of paracetamol, tryptophan, and caffeine have not been reported so far, and we report an electrochemical sensor via incorporating tin sulfide (SnS) and titanium dioxide (TiO 2 ) on graphene oxide (GO) sheets (SnS/TiO 2 @GO ternary composite) for their separate and simultaneous determination through cyclic voltammetry and differential pulse voltammetry techniques. The surface morphology and structural properties of the composite were characterized by analytical techniques. The electrochemical study of SnS/TiO 2 @GO composite modified glassy carbon electrode (GC-SnS/TiO 2 @GO) showed high activity toward the oxidation of paracetamol, tryptophan, and caffeine with significant decrease in overpotential due to large surface and high carrier mobility. The peak currents during separate determination of paracetamol, tryptophan, and caffeine increased linearly with the increase in concentration from 9.8 nM to 280 μM for paracetamol, from 13.3 nM to 157 μM for tryptophan, and from 16.6 nM to 333 μM for caffeine. The detection limit (3σ/S) was 7.5, 7.8, and 4.4 nM for paracetamol, tryptophan, and caffeine, respectively. The electron transfer coefficient (α), surface coverage concentration (Γ), number of electrons transferred (n), and diffusion coefficient (D) were calculated and discussed. The fabricated electrode showed low detection limit, wide linear range, and excellent reproducibility, selectivity, and stability. The study was also extended to the analysis of commercial tablets, beverage and human blood serum.Therefore, the present electrode holds great promise for identification and quantification of drugs in combination.

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In the present study, a electrochemical sensor for the determination of dopamine was developed with green synthesised gold nanoparticles using curcumin as a reducing and, functionalizing agent.

Hydrogen Sulfide (H2S) is a common toxic gas released into the environment mainly during the energy production process from coal and crude oil. H2S causes several neurological damages to the human body which could also be fatal and thus needs to be monitored. Here, we report the incorporation of reduced graphene oxide (rGO) on β-Ga2O3 (β-Ga2O3/rGO) sensing layers followed by its deposition on alumina substrate by drop casting method for H2S gas sensing application. The structure and phase purity of the synthesized β-Ga2O3, GO and β-Ga2O3/rGO samples were characterized using X-ray diffraction (XRD). The gas sensing properties of the coated sensing layers of β-Ga2O3 and β-Ga2O3/rGO were analyzed by Electrochemical Impedance Spectroscopy (EIS) at 100 °C. The gas sensing results revealed superior sensitivity and selectivity of β-Ga2O3/rGO towards H2S detection when compared with different interfering gases (NH3, SO2, CO2 and CO). Nyquist plots and equivalent circuit fitting values clearly indicate that the grain boundary resistance was highly affected in H2S gas environment (3 ppm) compared to other interfering gases. Based on the findings the gas sensing mechanism is proposed.

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Four different novel magnetic core–shell nanocomposites stabilized with Au/Pd nanoparticles (NPs) were prepared by a simple procedure and demonstrated their catalytic activity for effective cleavage of pBR322 DNA. Initially, the Fe3O4–poly(styrene-divinylbenzene-vinylbenzyl chloride) (ST-DVB-VBC) matrix functionalized with 3-aminobenzoic acid was prepared and grafted with PPI-G(2) and PPI-G(3) dendrimers. Each core–shell matrix was immobilized with AuNPs and PdNPs separately. The resulting composites were characterized by FT-IR, UV–vis, SEM, TEM, XRD, VSM, XPS, Raman, and TGA. The magnetic core–shell nanocomposites at concentrations from 30 to 50 μM were employed separately to study DNA cleavage by agarose gel electrophoresis. Among the four magnetic core–shell nanocomposites, Fe3O4–poly(ST-DVB-VBC)–PPI-G(3)–AuNPs showed higher activity than others for DNA cleavage, and formed Form-II and -III DNA. When the concentration of Fe3O4–poly(ST-DVB-VBC)–PPI-G(3)–AuNPs was increased from 40 to 45 and 45 to 50 μM, Form-III (linear) DNA was observed with 10 and 22%, respectively, in addition to Form-II. This observation suggests formation of linear DNA from the supercoiled DNA via nicked DNA-intermediated consecutive cleaving process. The magnetic core–shell nanocomposites were stable and monodispersed, and exhibited rapid magnetic response. These properties are crucial for their application in biomolecular separations and targeted drug-delivery in the future.