Synthesis, electrodynamics and biosensor applications of novel sulphonated polyaniline nanocomposites

Philosophiae Doctor - PhDThe overall aim of this thesis was to prepare nanostructured more processable heteronuclear sulphonated polyanyline nanocomposites with electroconductive properties suitable for applications in biosensors. The sulphonated self-assembled polyaniline and derivatised polyaniline nanocomposites (SPAHs) were prepared by chemical oxidative polymerisation or electrical decomposition. The SPAHs prepared include those of polyaniline (PANi), poly-o-methoxyaniline (POMA) and poly-2.5 dimethoxyaniline (PDMA). Two types of sulphonic acids of heteronuclear aromatic hydrocarbons were used in the production of sulphonated SPAH composites. These were anthracene sulphonic acid (ASA) and naphthalene sulphonic acids (NSA) wich played both doping and surfactant roles.South Afric

Silver–zinc oxide nanocomposite antiseptic from the extract of Bidens pilosa

Silver nanoparticles (Ag-NPs), zinc oxide (ZnO-NPs) and zinc oxide–silver (ZnO–Ag-NPs) were biosynthesized based on the rich matrix of alkaloids, flavones, tannins capping/stabilizing agents present in Bidens pilosa extract. Different plant parts-root, leaf and seed ware used to prepare the plant extract for synthesis. Also, zinc and silver nitrate salts were used as precursor materials. The surface plasmon peaks (SPR) based on the UV–Vis results for the Ag-NPs, ZnO-NPs were located between 408–411 and 365–450 nm respectively. The SPR peaks for the Ag–ZnO-NPs occurred at 300–450 nm indicating both blue and red shifts. The Ag–ZnO-NPs SPR shifts were associated with possible nanoparticle size reduction and change in dielectric constant of the synthesis medium. Raman measurement peaks at 356, 484, 1350, 1578, 2435 cm−1 associated with OH, –C==C–, –C–O, S=O, =C–H moieties indicated successful capping. Nanoparticle yield was temperature dependent and optimal yield could not be tied to a particular plant part as source of extract. Tunneling electron microscope results showed Ag-NPs and ZnO-NPs were globular/spherical with a diameter range of 2–20 nm. Interestingly, ZnO-NPs TEM displayed isolated miniaturized globular nanoparticles (< 2 nm) which then joined up to form a large donut shaped structure indicating different formation mechanisms for the nanoparticles. XRD results showed the Ag-NPs, ZnO-NPs and the Ag–ZnO-NPs particles were crystalline in nature

Development and Applications of a Simple Spectrophotometric Method for Determination of Bisphenol A in ‘New’ and ‘Used’ Polycarbonate Baby Feeding and Water Bottles

Recently endocrine disorders have become a big concern. Endocrine-disrupting chemicals are contaminants interfering with hormone biosynthesis, metabolism, or change how the endocrine system works. Bisphenol A is an endocrine disruptor having weak estrogenic activity and competes with body native estrogen. Polycarbonate containers are known to be major sources of bisphenol A that leaches to the container’s content through hydrolysis. This study aimed at monitoring levels of bisphenol A exposure to polycarbonate users through a novel spectrophotometric technique. The polycarbonate samples used were baby feeding bottles and portable water bottles. The Spectroscopic method employed a diazotization reaction procedure resulting in the formation of yellow azo-dye that is easily detected using UV-Vis spectroscopy. Prior to use, the sampled ‘suspected’ polycarbonate bottles were verified to be Polycarbonate using Fourier transform infrared spectroscopy.The Fourier transform infrared spectra of thin plastic solids were identified by scanning between, 500-4000 cm-1 for characterization. The resulting spectra were compared with those of standard polycarbonate plastics reported in the literature. Characteristic polycarbonate peaks at 2970, 1970, 1504, 1187, 1013, 1079 cm-1 associated with the –C-H, C=O, C=O, O-C-O, -CH3 stretching vibrations respectively confirmed sampled bottles were polycarbonates.  Bisphenol A levels for all the sampled polycarbonate bottles in the various environments ranged between 0.17 – 2.82 µgmL-1.  All the samples surpassed the tolerable daily intake for BPA of 4 ?g/kgbw/day recommended by the European Food Safety Authority and this calls for serious consideration

Synthesis, Characterization of Green Tea Stabilized Iron Nanoparticles and their Synergistic Effect on Polyaniline

This work reports the synthesis of polydisperse iron nanoparticles (FeNPs) stabilized on green tea polyphenol stabilizing and capping agents

Electroconductive Polyaniline&ndash;Ag-ZnO Green Nanocomposite Material

Metal-conducting polyaniline (PANI)-based nanocomposite materials have attracted attention in various applications due to their synergism of electrical, mechanical, and optical properties of the initial components. Herein, metal-PANI nanocomposites, including silver nanoparticle-polyaniline (AgNP-PANI), zinc oxide nanoparticle-polyaniline (ZnONP-PANI), and silver-zinc oxide nanoparticle-polyaniline (Ag&ndash;ZnONP-PANI), were prepared using the two processes. Nanocomposite-based electrode platforms were prepared by depositing AgNPs, ZnONPs, or Ag&ndash;ZnONPs on a PANI modified glass carbon electrode (GCE) in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-Hydroxysuccinimide (EDC/NHS, 1:2) as coupling agents. The incorporation of AgNPs, ZnONPs, and Ag&ndash;ZnONPs onto PANI was confirmed by UV-Vis spectrophotometry, which showed five absorbance bands at 216 nm, 412 nm, 464 nm, 550 nm, and 831 nm (i.e., transition of &pi;-&pi;*, &pi;-polaron band transition, polaron-&pi;* electronic transition, and AgNPs). The FTIR characteristic signatures of the nanocomposite materials exhibited stretching arising from C&ndash;H aromatic, C&ndash;O, and C&ndash;N stretching mode for benzenoid rings, and =C&ndash;H plane bending vibration formed during protonation. The CV voltammograms of the nanocomposite materials showed a quasi-reversible behavior with increased redox current response. Notably, AgNP&ndash;PANI&ndash;GCE electrode showed the highest conductivity, which was attributed the high conductivity of silver. The increase in peak currents exhibited by the composites shows that AgNPs and ZnONPs improve the electrical properties of PANI, and they could be potential candidates for electrochemical applications