Au@Pt core@shell NPs were synthesized by a galvanic displacement reduction method and fabricated on an electrode surface for the investigation of methanol oxidation and oxygen reduction reactions.

The present study describes the facile and fast growth of Ag–Cu dendritic nanostructures (D-AgCuNSs) via an environmentally benign electro–electroless deposition method and determination of hydrazine (HZ) in water samples using the resultant D-AgCuNSs-grown indium tin oxide (ITO) electrode. HZ was also successfully determined with the aid of Raman spectroscopy, in which the Raman signal was enhanced 15-fold at D-AgCuNSs in the presence of HZ, in contrast to bare ITO. Initially, CuNSs were grown on the ITO substrates at different applied potentials and the resultant substrates were used in the galvanic displacement reaction with Ag+ ions and thereby grown D-AgCuNSs on the ITO substrate. The growth of D-AgCuNSs was followed by scanning electron microscopy (SEM), with respect to time and Ag+ concentration. The D-AgCuNSs grown on ITO substrates were further characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive spectroscopy (EDS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. XPS shows that the grown D-AgCuNSs contain zerovalent Ag and Cu. Furthermore, the D-AgCuNSs-modified ITO electrode was utilized for carcinogenic HZ determination and excellent catalytic activity was observed at this electrode, in contrast to bare and Cu-modified ITO electrodes. The amperometric determination was accomplished with a wide range of HZ concentrations, from 20 × 10–9 M to 50 × 10–6 M (correlation coefficient of R 2 = 0.9934). Furthermore, the ITO/D-AgCuNSs electrode detects HZ with the superior selectivity of 2500-fold in the presence of common interfering ions and biological compounds. The lowest limit of detection (0.12 nM (signal-to-noise (S/N) ratio of 3)) and superior sensitivity (3722 μA mM–1 cm–2) were achieved toward HZ. In addition, the present sensor was exploited for the determination of HZ in environmental samples and exhibits excellent recovery.

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The present work describes highly selective and sensitive determination of vitamin B1 (thiamine) using 4-amino-6-hydroxy-2-mercaptopyrimidine capped gold nanoparticles (AHMP-AuNPs) by spectrofluorimetry. The AHMP-AuNPs were synthesized by wet chemical method and were characterized by HR-TEM, XRD, UV-visible, zeta potential and spectrofluorimetry. They show emission maximum at 781 nm while exciting at 520 nm and a large stock shift (261 nm) with a narrow emission profile and good photostability. While adding 0.15 µM thiamine, the red color solution of AHMP-AuNPs changes to purple and the absorbance at 520 was decreased. This is due to the aggregation of AHMP-AuNPs and it was confirmed by HR-TEM. No change in absorbance was observed in the UV-visible spectra for AHMP-AuNPs in the presence of less than micromolar concentration of thiamine. On the other hand, the emission intensity of AHMP-AuNPs was enhanced even in the presence of picomolar concentration of thiamine. Based on the enhancement of emission intensity, the concentration of thiamine was determined. Interestingly, no change in the emission intensity was observed while adding even milli molar concentration of other vitamin B complexes. The present fluorophore showed an extreme selectivity towards the determination of thiamine in the presence of 10,000 fold common interferents including vitamin B2, B3, B6, B9 and vitamin C while the presence of cysteine and glutathionine interferes for the determination of thiamine. A good linearity was observed from 10 to 120 × 10 -12 M thiamine and a detection limit was found to be 6.8 fM/L (S/N = 3). The present method was successfully used for the determination of thiamine in human blood serum samples.of Technology, Trichy, for providing the instrument facility and PSG Institute of Advanced Studies, Coimbatore for HR-TEM measurements. Address

A novel organic-inorganic nile-blue-CeO2 (CeO2/NB) nanohybrid has been synthesized by environmentally benign ultrasonic irradiation method for the selective determination of the environmental pollutant, carcinogenic hydrazine (HZ) in environmental water samples. Hydrophobic dyes have generally been as redox mediators in electrochemical sensors fabrication due to strong electron transfer capacity and they would allow the oxidation and reduction of the analytes at lower potentials. The CeO2 nanoparticles were initially synthesized by the ultrasonic irradiation of Ce(NO3)2, NH4OH and ethylene glycol mixture for 6 h using probe sonicator (20 kHz, 100 W) followed by calcination. The organic-dye NB was then added and ultrasonicated further 30 min for the formation of CeO2/NB nanohybrid material. Various spectroscopic and microscopic tools such as UV-vis and FT-IR spectroscopy, XRD, SEM and high-solution TEM and surface analysis tool Brunauer-Emmett-Teller (BET) confirm the formation of the nanohybrid. HR-TEM images showed the well-covered CeO2 on NB molecules and the average size of the nanohybrid is ~35 nm. For the fabrication of environmental pollutant electrochemical sensor, the prepared CeO2/NB nanohybrid was drop-casted on the electrode surface and utilized for the determination of HZ. The nanohybrid modified electrode exhibits higher electrocatalytic activity by showing enhanced oxidation current and less positive potential shift towards HZ oxidation than the bare and individual CeO2 and NB modified electrodes. The fabricated sensor with excellent reproducibility, repeatability, long-term storage stability and cyclic stability exhibited the sensational sensitivity (484.86 µA mM−1 cm−2) and specificity in the presence of 50-fold possible interfering agents with the lowest limit of detection of 57 nM (S/N = 3) against HZ. Utilization of the present sensor in environmental samples with excellent recovery proves it practicability in the determination of HZ in real-time application.

The application of red luminescence BSA-AuNCs towards the selective determination of food additive tert-butylhydroquinone (TBHQ) was demonstrated by both fluorometric and colorimetric methods.

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