Aftab Aslam Parwaz Khan

Lead sensors development and antimicrobial activities based on graphene oxide/carbon nanotube/poly(O-toluidine) nanocomposite.

Graphene oxide/carbon nanotube/poly (O-toluidine) (GO-CNT-POT) nanocomposite was prepared by a situ polymerization method and characterized by X-ray powder diffractometry (XRD) and scanning electron microscopy (SEM). The antibacterial activity of the obtained GO-CNT-POT nanocomposite was also evaluated against Gram positive bacteria Bacillus subtilis, Gram negative bacteria Escherichia coli and antibiotics (Amoxicillin) using the agar plate. The antibacterial study showed that the GO-CNT-POT was found to be most effective against both B. subtilis and E. coli respectively which was significant compared to the amoxicillin and the simultaneously GO-CNT-POT nanocomposite were fabricated onto glassy carbon electrode (GCE) using conducting coating binders by I-V technique, where the total analytical parameters were measured for the development of sensitive lead sensors (Pb(2+)). The GO-CNT-POT nanocomposite were deposited on flat-GCE (surface area: ∼0.0316cm(2)) to result in a sensor that has a fast response to selective Pb(2+) ions in buffer system. Features including sensitivity, detection limit, reproducibility, linear dynamic range, selectivity, and electrochemical performances were investigated in details with the GO-CNT-POT nanocomposite fabricated GCE electrodes. The calibration plot is linear (r(2): 0.9907) over the large concentration range (0.1nM to 1.0mM). The sensitivity and detection limit is calculated as 8.53164μAcm(-2)μM(-1) and 89.0 pM (at a signal-to-noise-ratio, SNR of 3) respectively.

Mixed micellization of gemini surfactant with nonionic surfactant in aqueous media: a fluorometric study

Herein we report on the study of the interactions between alkanediyl-α,ω-type cationic dimeric (gemini) surfactant and the nonionic Triton X-100 in aqueous medium. The critical micelle concentrations of binary mixtures were determined by fluorometric study. Using the regular solution theory for the analysis of the experimental data, the attractive nature of interactions and synergistic behavior of gemini surfactant and Triton X-100 mixture were demonstrated. The micelle aggregation number was measured using steady state fluorescence quenching method. The micropolarity, binding constant and dielectric constant of mixed systems were determined from the ratio of peak’s intensity (I1/I3) in the pyrene fluorescence emission spectrum.

Sensor development of 1,2 Dichlorobenzene based on polypyrole/Cu-doped ZnO (PPY/CZO) nanocomposite embedded silver electrode and their antimicrobial studies

Cu-doped ZnO nanopowders and their composites of polypyrole (PPY)/CZO were prepared by a gel combustion method and an in-situ polymerization process, respectively. The synthesized nanocomposite are characterized by X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), FTIR, and TGA studies. Then the PPY/CZO/AgE nanocomposites were used for potential application in chemical sensing by easy and reliable I-V method, where 1,2 dichlorobenzene (1,2-DCB) is considered as a model target compound. The chemical sensor performances are exhibited the higher sensitivity, good stability, and repeatability of the sensor enhanced significantly using PPY/CZO/AgE of thin-film with conducting binders on silver electrodes (AgE; Surface area: 0.0216cm2). The calibration plot is linear over the large dynamic range (0.35nM∼3.5mM), where the sensitivity (∼2.702μAmM-1cm-2) and detection limit (∼0.34nM) is calculated based on signal/noise ratio (∼3N/S) in short response time. Finally, it is concluded that the structural and optical characteristics could be encompassed to a broad-scale in PPY/CZO/AgE composites and efficient chemical sensor applications for environmental fields. Simultaneously PPY/CZO composites was also evaluated against Gram positive bacteria Bacillus subtilis, Gram negative bacteria Escherichia coli and antibiotics (Amoxicillin) using the agar plate.

A New Trend on Biosensor for Neurotransmitter Choline/Acetylcholine—an Overview

Technology always has been an indispensible part in the development of biosensors. The performance of biosensors is being tremendously improved using new materials as transducer as well as binding material in their construction. The use of new materials allowed innovation on transduction technology in biosensor preparations. Because of the submicron dimensions of these sensors, simple and rapid analyses in vitro as well as in vivo are now possible. Portable instruments capable of analysing multiple components are becoming available, too. Sensors that provide excellent temporal and spatial resolution for in vivo monitoring such as for measurement of neurotransmitters have become prominent. The interest to improve the stability, sensitivity and selectivity of the sensors is paramount. This study tries to give an overview of the present status of the material-based biosensor design and new generation of choline/acetylcholine neurotransmitter biosensors.

Clouding Behavior of Amphiphilic Drug Clomipramine Hydrochloride with Pharmaceutical Excipients

Abstract The clouding behavior of amphiphilic drug clomipramine hydrochloride (CLP) in presence of different additives like bile salts, hydrotropes (anionic, cationic and nonionic), fatty acids, sugars and cyclodextrin has been investigated. These additives are commonly used as drug delivery systems. The additives like anionic hydrotropes, bile salts and fatty acid salts increase the cloud point (CP) of CLP, when added in low concentrations, whereas at high concentration, decrease it. Cationic and nonionic hydrotropes increase the CP of CLP at all concentrations. All sugars decreased the CP because of their water structure making property. β-cyclodextrin behaves like simple sugar and decreases the CP of the drug solutions. The thermodynamic parameters are also evaluated: where ΔGc° is found to be negative and ΔHc° and TΔSc° values are negative as well as positive depending upon type and nature of additive.

Preparation, Electrical Conductivity, and Thermal Studies on Silver Doped Polyaniline Phosphotungstate Nanocomposite

Silver doped polyaniline phosphotungstate (PANI-PW/Ag) composite was synthesized sol-gel method and treated with silver nitrate resulting silver doped PANI-PW/Ag. Physicochemical characterization of PANI-PW/Ag was carried out by scanning electron microscopy and Fourier transform infrared spectroscopy (FT-IR). Electrical conductivity measurements and thermal effect on conductivity of PANI-PW/Ag was also studied after treatment with HCl. The dc conductivity was found within the range of 4.82 × 10−3 S/cm−1 for HCl doped, measured by 4-in line–probe dc electrical conductivity measuring technique. Thermal conductivity is stable with all temperatures in isothermal studies showing excellent stability of PANI-PW/Ag material.

Synthesis of Silver Embedded Poly(o-Anisidine) Molybdophosphate Nano Hybrid Cation-Exchanger Applicable for Membrane Electrode

Poly(o-anisidine) molybdophosphate was expediently obtained by sol-gel mixing of Poly(o-anisidine) into the inorganic matrices of molybdophosphate, which was allowed to react with silver nitrate to the formation of poly(o-anisidine) molybdophosphate embedded silver nano composite. The composite was characterized by Fourier Transform Infrared Spectroscopy, X-ray powder diffraction, UV-Vis Spectrophotometry, Fluorescence Spectroscopy, Scanning Electron Microscopy/Energy-dispersive X-ray Spectroscopy and Thermogravimertic Analysis. Ion exchange capacity and distribution studies were carried out to understand the ion-exchange capabilities of the nano composite. On the basis of highest distribution studies, this nano composite cation exchanger was used as preparation of heavy metal ion selective membrane. Membrane was characterized for its performance as porosity and swelling later on was used for the preparation of membrane electrode for Hg(II), having better linear range, wide working pH range (2–4.5) with fast response in the real environment.

Spectrophotometric interaction of the oxidation of captopril by hexacyanoferrate(III) in an alkaline medium: a kinetic and mechanistic approach

Spectrophotometric kinetic interaction of the oxidation of captopril (CPL) by hexacyanoferrate(III) (HCF(III)) in an alkaline medium has been studied spectrophotometrically. The reaction showed firstorder kinetics. The rate of the reaction increased with an increase in alkali concentration. Increasing ionic strength increased the rate of the reaction.A mechanism involving the formation of a complex between CPL and HCF(III) has been proposed. The reaction constants involved in the mechanism have been evaluated. There is a good agreement between the observed and calculated rate constants under different experimental conditions. Investigations at different temperatures allowed the determination of the activation parameters with respect to the slow step of the proposed mechanism.

Resonance Rayleigh Scattering Spectra, Nonlinear Scattering Spectra of Selected Cephalosporins-Cd(II) Chelate with Titan Yellow and Their Analytical Applications

Three simple and highly sensitive methods were designed for the determination of cephalosporins antibiotics (CFs) such as cefpodoxime proxetil (CFPD), cefdinir (CFDN), and cefuroxime axetil (CFRX) by means of the enhancement effect on resonance Rayleigh scattering (RRS) and nonlinear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS) intensities. All CFs under this project reacts with Cd(II) in BR buffer medium of pH 3.4 to form 1:1 cationic chelate which further react with titan yellow to form 2:1 ion association complexes as a result, RRS, SOS, and FDS intensities were markedly enhanced. The increments of scattering intensities were directly proportional to the concentration of CFs antibiotics in a certain range. The detection limit for the three CFs were 1.73–2.38 ng ml−1 for RRS method, 5.12–5.67 ng ml−1 for SOS, 6.25–7.26 ng ml−1 for FDS method, respectively. Among them the RRS method exhibited the highest sensitivity and the CFPD system was more sensitive then other antibiotics systems. The optimum reaction conditions, the effects of coexisting substances, the structure of ternary complexes, and the reaction mechanism were discussed. The methods were applied to the determination of CFs in pharmaceutical samples with satisfactory results.

Preparation of polyaniline grafted graphene oxide–WO3 nanocomposite and its application as a chromium(III) chemi-sensor

A nanohybrid of polyaniline grafted graphene oxide@WO3 (PANI-g-rGO@WO3) was prepared by oxidative polymerization of aniline in the presence of tungsten oxide and reduced graphene oxide. The physicochemical characterization of PANI-g-rGO@WO3 was done by FESEM, X-ray diffraction microscopy, FTIR, UV-Vis spectroscopy, thermogravimetric analysis and XPS. The composite was analyzed for hazardous metal selectivity and was found to be highly sensitive for trivalent chromium (Cr3+). For potential trivalent chromium (Cr3+) cation sensor development, the PANI-g-rGO@WO3 nanocomposite was deposited on a flat silver electrode (AgE, surface area, 0.0216 cm2) with conducting binders coating to give a sensor with a fast selective response towards trivalent chromium cations in the liquid phase. The sensor also exhibits good sensitivity, long-term stability, and enhanced electrochemical responses. The calibration plot is linear (r2 = 0.9815) over a 0.1 nM to 0.01 M Cr3+ concentration range. The sensitivity is ∼4.4251 μA mM−1 cm−2 and the detection limit is 0.031 ± 0.010 nM (signal-to-noise ratio, at a SNR of 3). The development of a sensitive sensor for hazardous and carcinogenic chromium cations is also commenced using the PANI-g-rGO@WO3 nanocomposite and the I–V method for promising potential future applications in the environmental and healthcare fields.