Mangaka Matoetoe

Development of a silver functionalised polyaniline electrochemical immunosensor for polychlorinated biphenyls

An electrochemical immunosensor based on a silver nanoparticles (Ag NPs)-doped polyaniline (PANI) modified glassy carbon electrode (GCE) transducer, wherein polyclonal anti-polychlorinated biphenyl (PCB) antibody (Ab) was immobilized by a covalent linkage with glutaraldehyde (GA), was developed. The optimum conditions for the fabrication of the immunosensor were immersion, 30 min incubation in 1.0% GA. Electrochemical measurements of PCB 28 were done using the square wave voltammetry (SWV) technique. The optimum methodology conditions were a 20 mV s−1 scan rate, sweep potential range of −1 to 1 V and PCB incubation period of 2 h. The electrochemical response obtained under these optimum conditions was linear within 0.2 and 1.2 ng mL−1 with limit of detection (LOD) and limit of quantitation (LOQ) values of 0.063 ng mL−1 and 0.209 ng mL−1, respectively. The specificity of the developed sensor towards PCB 28 against benzyl chloride (BnCl) and PCB 180 was poor due to structural similarities. However, the PCB 180 results correspond to total PCB, thus indicating the sensors applicability to regular total PCB determination. Cations and anions tested had a minimum effect on the sensor. Recoveries in water and guava juice ranged from 90% to 102%. Thus, proving the immunosensors selectivity to PCBs and its possible application in the detection and monitoring of PCBs in food, water bodies and general environmental samples.

X-ray diffraction and band gap studies of bimetallic silver-platinum nanoparticles

X-beam imaging of mice utilizing a colloid arrangement of Au nanoparticles that were covered with silica and hence surface-adjusted with carboxymethylcellulose (CMC) (Au/SiO2/CMC) was acted in this work. The silica-covering for Au nanoparticles and the amination for silica-covered particles were at the same time acted within the sight of the Au nanoparticles with a size of 17.9 nm, which were set up by decreasing Au particles (III) with sodium citrate in water at 80°C and by surface-changing the Au nanoparticles with (3-aminopropyl)- trimethoxysilane, by a sol-gel measure utilizing tetraethylorthosilicate, (3-aminopropyl)- triethoxysilane, water and sodium hydroxide (Au/SiO2-NH2). The surface alteration of Au/SiO2-NH2 particles with CMC was performed by essentially adding CMC with carboxyl gatherings that respond with an amino gathering to the Au/SiO2-NH2 molecule colloid arrangement. The as-arranged the Au/SiO2/CMC molecule colloid arrangement was concentrated by centrifugation for estimations utilizing figured tomography (CT). Figure 1 shows a photo of the concentrated molecule colloid arrangement and a conveyance electron microscopy picture of the Au/SiO2/CMC particles in the concentrated colloid arrangement. Most particles contained a solitary center of the Au nanoparticles. Their molecule size was 67.4±5.4 nm. A CT estimation of the Au/SiO2/CMC molecule colloid arrangement with an Au convergence of 0.043 M was as high as 344±12 Hounsfield units (HU). This worth compared to 8.0×103 HU/M as for the Au fixation, which was bigger than that of Iopamiron 300, a business X-beam contrast specialist. Mouse tissues were imaged following infusion of the Au/SiO2/CMC molecule colloid arrangement.

Electrochemical Characterization of Silver-Platinum Various Ratio Bimetallic Nanoparticles Modified Electrodes

Silver-platinum (Ag-Pt) bimetallic nanoparticles (NPs) with varying mole fractions (1:1, 1:3 and 3:1) were prepared by co-reduction of hexachloroplatinate and silver nitrate with sodium citrate. Upon successful formation of monometallic and bimetallic (BM) core shell nanoparticles, cyclic voltammetry (CV) was used to characterize the NPs. The drop coated nanofilms on the GC electrode showed characteristic peaks of monometallic Ag NPs; Ag+/Ag0 redox couple as well as the Pt NPs; hydrogen adsorption and desorption peaks. Varying current trends were observed in the BM NPs ratios as; GCE/Ag-Pt NPs 1:3 > GCE/Ag-Pt NPs 3:1 > GCE/Ag-Pt NPs 1:1. Fundamental electrochemical properties such as; diffusion coefficient (D), electroactive surface coverage, electrochemical band gaps and electron transfer coefficient (α) and charge (Q) were assessed using Randles - Sevcik plot. High charge and surface coverage was observed in GCE/Ag-Pt NPs 1:3 accounting for its enhanced current. GCE/Ag-Pt NPs 3:1 showed high diffusion coefficient while GCE/Ag-Pt NPs 1:1 possessed high electron transfer coefficient, which is facilitated by its heterogeneous rate constant relative to other BM NPs ratios. Surface redox reaction was determined as adsorption controlled in all modified GCEs.

Potential of Silver Nanoparticles Functionalized Polyaniline as an Electrochemical Transducer

Modification of commercial platinum (Pt) and glassy carbon (GC) electrodes with polyaniline (PANI) and silver nanoparticles doped polyaniline (PANI/Ag NPs) through electropolymerization of aniline in the absence and presence of Ag NPs in 1 M hydrochloric acid (HCl) was interrogated. Fourier transform infrared (FTIR) and transmission electron microscope (TEM) techniques were used for structural, compositional and morphological elucidation. FTIR spectra for PANI and PANI/Ag NPs had the characteristic PANI functional groups as well as desired bands for the conducting emeraldine (EM) form. The predominance of the PANI pattern in the spectra is indicative of the intact PANI structure in the presence of Ag NPs while the slight band shifts are signify interfacial interactions between PANI and Ag NPs. TEM micrograms depicts different size one dimensional nanofibric tubes of the supramolecular structures of PANI. Ag NPs functionalized PANI had larger smoother tubes, suggesting organized morphology arrangement. An increased energy dispersive spectroscopy (EDS)-TEM count from 256 to 277 confirms incorporation of Ag NPs in PANI. GC/PANI/Ag NPs exhibited outstanding electroactivity (higher conductivity and rate of electron transfer).This might be a result of the large surface coverage, film thickness and diffusion coefficient as a result of the large GC surface area. Possibly, the improvement might be due to the GC electrode properties. The electroactivity of the electrodes increased in the order: Pt < GC < Pt/PANI < Pt/PANI/Ag NPs < GC/PANI < GC/PANI/Ag NPs. The effect of Ag NPs in the polymer was demonstrated by ultimate band gap reduction of PANI and enhanced magnitudes of current response per electrode.