Nazar Hussain Kalwar

l-cysteine protected copper nanoparticles as colorimetric sensor for mercuric ions

This report demonstrates a novel, simple and efficient protocol for the synthesis of copper nanoparticles in aqueous solution using L-cysteine as capping or protecting agent. UV-visible (UV-vis) spectroscopy was employed to monitor the LSPR band of L-cysteine functionalized copper nanoparticles (Cyst-Cu NPs) based on optimizing various reaction parameters. Fourier Transform Infrared (FTIR) spectroscopy provided information about the surface interaction between L-cysteine and Cu NPs. Transmission Electron Microscopy (TEM) confirmed the formation of fine spherical, uniformly distributed Cyst-Cu NPs with average size of 34 ± 2.1 nm. X-ray diffractometry (XRD) illustrated the formation of pure metallic phase crystalline Cyst-Cu NPs. As prepared Cyst-Cu NPs were tested as colorimetric sensor for determining mercuric (Hg(2+)) ions in an aqueous system. Cyst-Cu NPs demonstrated very sensitive and selective colorimetric detection of Hg(2+) ions in the range of 0.5 × 10(-6)-3.5 × 10(-6) mol L(-1) based on decrease in LSPR intensity as monitored by a UV-vis spectrophotometer. The developed sensor is simple, economic compared to those based on precious metal nanoparticles and sensitive to detect Hg(2+) ions with detection limit down to 4.3 × 10(-8) mol L(-1). The sensor developed in this work has a high potential for rapid and on-site detection of Hg(2+) ions. The sensor was successfully applied for assessment of Hg(2+) ions in real water samples collected from various locations of the Sindh River.

Ultra-fast catalytic reduction of dyes by ionic liquid recoverable and reusable mefenamic acid derived gold nanoparticles.

We synthesized mefenamic acid (MA) derived gold nanoparticles (MA-AuNps) in aqueous solution (MA-Au sol). Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) of the sol at 1, 5, 15 and 60 min showed changes in size and shape of formed AuNps. Fourier Transform Infrared (FTIR) Spectroscopy revealed the interaction between AuNps and MA. Each Au sol exhibited exceptional catalytic activity for the reduction of Methylene Blue (MB), Rose Bengal (RB) and Eosin B (EB) dye individually as well as collectively. However, complete reduction of dye(s) was accomplished by Au sol of 5 min in just 15s. The catalytic performance of Ma-Au sol was far superior to that adsorbed on glass. AuNps were recovered with the help of water insoluble room temperature ionic liquid and reused with enhanced catalytic potential. This finding is a novel, rapid and highly economical alternative for environmental safety against pollution by dyes and extendable for control of other reducible contaminants as well.

Estimation of ibuprofen in urine and tablet formulations by transmission Fourier Transform Infrared spectroscopy by partial least square

A rapid, reliable and cost effective analytical procedure for the estimation of ibuprofen in pharmaceutical formulations and human urine samples was developed using transmission Fourier Transform Infrared (FT-IR) spectroscopy. For the determination of ibuprofen, a KBr window with 500 μm spacer was used to acquire the FT-IR spectra of standards, pharmaceuticals as well as urine samples. Partial least square (PLS) calibration model was developed based on region from 1807 to 1,461 cm(-1) using ibuprofen standards ranging from 10 to 100 μg ml(-1). The developed model was evaluated by cross-validation to determine standard error of the models such as root mean square error of calibration (RMSEC), root mean square error of cross validation (RMSECV) and root mean square error of prediction (RMSEP). The coefficient of determination (R(2)) achieved was 0.998 with minimum errors in RMSEC, RMSECV and RMSEP with the value of 1.89%, 1.63% and 4.07%, respectively. The method was successfully applied to urine and pharmaceutical samples and obtained good recovery (98-102%).

Synthesis and Characterization of Highly Efficient Nickel Nanocatalysts and Their Use in Degradation of Organic Dyes

The present study describes the synthesis of highly active and ordered structures of nickel nanocatalysts by a facile, green, and economically viable approach. The study reveals efficient catalytic activity for the degradation of a number of toxic organic dyes, such as eosin-B (EB), rose bengal (RB), eriochrome black-T (ECBT), and methylene blue (MB). The stable ordered nickel nanostructure (Ni NSs) arrays were prepared via a modified hydrazine reduction route with unique and controlled morphologies in a lyotropic liquid crystalline medium using a nonionic surfactant (Triton X-100). Characterization and optimization studies for the fabricated Ni NSs involving their surface binding interactions, size, and morphologies were carried out using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM).

Highly sensitive electrochemical determination of captopril using CuO modified ITO electrode: the effect of in situ grown nanostructures over signal sensitivity

The study describes a new approach for the direct electro-oxidation of captopril (CAP) drug using a CuO modified ITO electrode. The modified ITO electrode consists of an in situ grown film which accommodates dense CuO nanostructures with morphological features similar to flowers. The in situ growth over the ITO substrate was achieved using a simple hydrothermal route with the assistance of malonic acid which acted as an effective growth template. The devised electrode was evaluated in reference to its slurry-derived counterpart which involved surface modification of GCE using a conventional approach (drop-casting). The competitive evaluation of the discussed electrodes against the electro-oxidation of CAP, provided significant evidence to support the importance of controlled nanostructure distribution over the electrode surface to achieve higher signal sensitivity and reproducibility. The devised ITO/CuO electrode was known to possess excellent sensing capability against CAP within the linear working range of 0.01 to 3.43 μM with signal sensitivity down to 2 × 10−3 μM. Moreover, the ITO/CuO was noted to exhibit high charge transfer co-efficient (α), diffusion co-efficient (D) and rate constant values of 0.83, 9.28 × 10−5 cm2 s−1 and 3.5 × 103 mol−1 L s−1 respectively. In addition, the successful usage of ITO/CuO for CAP determination from commercial tablets and human urine samples further indicated the practical workability of the proposed electrode system.