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Chromium is recognized as a serious environmental pollutant because of high toxicity and carcinogenic properties. In this paper, we have developed cadmium sulfide quantum dots (CdS QDs) based fluorescence sensor for sensitive and selective detection of chromium ions. CdS QDs were synthesized by wet chemical method using pectin biopolymer as capping agent and taurine as an antioxidant. The fluorescence emission intensity of CdS QDs at 450 nm was selectively quenched by chromium ions, whereas other cations and anions showed negligible changes. The fluorescence intensity of CdS QDs is linearly proportional to the chromium concentration from 0.016 to 0.260 μM with a detection limit of 16 × 10 −9 M. The proposed sensor recognizes chromium ion at a wide range of pH from 4 to 10. In addition, CdS QDs were also used to detect chromium ions in biological fluid, sewage water, pond water and tap water samples, with low interference. [ABSTRACT FROM AUTHOR]

Abstract A simple single-stage method, based on refluxing edible carrot with aqueous trisodium phosphate (TSP) has been reported to synthesize blue color luminescent carbon dots (CDs). Transmission electron microscopy (TEM) image showed that CDs are almost spherical in shape and the size is around 3–8 nm. Fourier-transform infrared (FTIR) and 1H NMR spectroscopy study revealed that the carbohydrates present in the carrot undergone carbonization to produce luminescent CDs. Optimization study indicate that refluxing 5 g of carrot in 80 mM TSP aqueous solution for 120 min is adequate to produce highly luminescent blue CDs. The CDs produced are used as luminophore to image bacteria through fluorescence microscopy. CDs have membrane good permeability and minimum toxicity against Gram-negative and Gram-positive bacteria. The CDs capability for direct reduction of silver ions to elemental silver (Ag0) and gold ions to elemental gold (Au0) without additional reducing and stabilizing agent was demonstrated. The resulting Ag and Au nanoparticles have a size of 8–22 nm and 5–15 nm, respectively. The catalytic activity of nanoparticles in the hydrogenation reaction was investigated. The results suggest that the nanoparticles had high catalytic activity in the sodium borohydride mediated hydrogenation of nitroaromatic compounds. Graphical abstract Unlabelled Image Highlights • Easily adaptable procedure to synthesis carbon dots was reported. • CDs has good membrane permeability to label live cells. • CDs reduces silver and gold ions into nanoparticles. • Silver and gold nanoparticles exhibit good catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Designer surfactants with C8 to C18 chain length designed, synthesized & studied. • Relationship between product yield, surfactant hydrophobicity and CMC identified • Key Intra/Inter C C & C N bond forming reactions performed. Designer micellar medium was explored for the transformation of diverse anilines to the corresponding densely substituted biologically relevant skatole derivatives in an aqueous medium via 5-exo-trig cyclization reaction. The scope of the reaction was extended to intermolecular Csp2-Csp2 and Csp2-N bond forming reactions in water. Systematic investigations revealed that altering hydrophobicity of surfactant influences the yield of both C C and C N bond forming reactions in water. [ABSTRACT FROM AUTHOR]

Herein, we report a facile method to synthesis copper nanoparticles (CuNPs) using fatty acid amide, N -lauryltyramine (NLTA) and hydrazine as capping and reducing agent, respectively. As prepared CuNPs aqueous solution appears brown in color and shows intense surface plasmon resonance (SPR) band at 580 nm. In presence of amino acid, cysteine (Cys), the brown CuNPs solution turned to olive green with concomitant change in SPR maximum, while other amino acids show negligible change in the color and UV–vis spectra of CuNPs. The spectrophotometry detection limit of the proposed sensor is 0.10 μM, whereas naked eye limit of detection was estimated to 20 μM. FTIR studies revealed that Cys forms layer on the surface of the CuNPs, which was further supported by electrochemical studies. The proposed method has been successfully validated by detecting Cys in blood plasma and tap water samples. [ABSTRACT FROM AUTHOR]