http://hdl.handle.net/10386/33 2013-06-16T12:53:38Z http://hdl.handle.net/10386/675 Title: Synthesis, characterization and kinetic studies of porphyrins with thiolated side chains for functionalization of paramagnetic iron-oxide- gold, core- shell nanoparticles Authors: Eshilokun, Adeolu O. Abstract: 5,1 0, ,15,20-Tetrakis[3-(3-thioacetoxypropoxy)phenyl]porphyrin a photosensitizer for photodynamic therapy (PDT) was synthesized from 3-hydroxybenzaldehyde. Acid and alkaline hydrolysis of the thioacetoxypropoxyphenyl porphyrin was attempted to afford a free base porphyrin, 5,10, 15,20-tetrakis[3-(3-thiolpropoxy)phenyl]porphyrin but not achieved. Spectroscopic data indicates that partial hydrolysis occurred. 1HNMR, 13CNMR, UV-Visible and Infra-red spectrometers were used to characterize all the compounds. The synthesized porphyrin was immobilized on gold coated superparamagnetic iron oxide (Fe304@Au) nanoparticles for possible use as a carrier or drug delivery system for the porphyrin to cancer sites. The use of magnetic nanoparticles for biomedical applications have been proposed to a large extent for several years. In recent years nanotechnology has developed to a stage that makes it possible to produce, characterize and specifically tailor the functional properties of nanoparticles for clinical applications. This has led to various opportunities such as improving the quality of magnetic resonance imaging, hyperthermia treatment for malignant cells, site-specific drug delivery and the manipulation of cell membranes. To this end a variety of iron oxide nanoparticles have been synthesized. Using co-precipitation method, nanoparticles comprised of gold shell and magnetite/maghemite were synthesized by overgrowing the gold shell onto the magnetic seeds using sodium citrates as a reducing agent. Oxidized magnetites (Fe304) fabricated by co-precipitation of Fe2+ and Fe3+ in strong alkaline solution were used as magnetic cores. These magnetic nanoparticles were characterized by Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), and X-ray diffraction spectroscopy (XRD). The transmission electron microscopy (TEM) image indicated that the particles were well dispersed nd spherical in shape with an average size of 34 - 58 nm with the mean particle diameter of 42.41 nm :!: 12.03 nm and standard deviation of (a) 0.27 nm indicating broad size distribution for the superparamagnetic iron oxide nanoparticles (SPION), the particle diameters for the gold coated SPION are in the range 34-54 nm while the average particle size as determined from the TEM image for the selected fraction is 44.26 nm :t 6.93 nm. The relative standard deviation of the sizes of the nanoparticles is 0.16 nm and the TEM for the functionalized gold coated SPION shows monodispersed particles which appear in spherical, cubic, irregular hexagon and oblong shapes with an average diameter of 44.65 nm. The HRTEM image, shows the existence of lattice planes which confirms the crystallinity of the material. The spacing between adjacent lattice planes is about 0.23 nm which corresponds to the (311) interplanar distance of Fe304 nanocrystals. Atomic force microscopy (ATM) was used to confirm the transmission electron microscopy (TEM) and HRTEM findings. The UV-Visible absorption spectra of the deionised water used in the procedure of preparation of the as-synthesized nanoparticles showed no absorption peak in a wavelength range of 350-750 nm, but after introducing the suspension of the Au-coated magnetic nanoparticles, an absorption peak located at 526 nm appeared which is ascribed to the surface plasmon of nanosized Fe304@Au nanoparticles. The kinetic studies using UV-visible spectrometer and the HRTEM images confirmed the adsorption of the porphyrin macromolecules as a coat on the magnetites particles. At a 5000 revolution per second (rps), aliquot sample of the aqueous phase of the suspension of 0.002 mM Fe304@Au in contact with the organic phase solution of the porphyrin taken for absorbance measurement at every 600 s showed a decrease in the concentration of the suspension while a noticeable and appreciable increase was also noted in the concentration of the porphyrin macromolecules measured at a A max of 420 nm representing the functionalized sample. A new absorption peak of 535 nm was recorded for the nanoparticle/porphyrin phase. A clear magnetic behaviour was established from the two different samples (coated and functionalised samples) using superconducting quantum interference device (SQUID) magnetometer. No long-range cooperative behaviour is evident anywhere from room temperature down to 2 K, which attests to a characteristic length of the scale of the Fe-magnetic agglomeratios on the nano-scale. Being especially prone to intrinsic ferromagnetic ordering, any impurity form of Fe or macro-scale Fe aggregates would impart a very large and easily identifiable magnetic signal. Such a reponse was completely absent from these stud ies and hence testifies to the homogeneity quality of the materials under investigation. KEY WORDS: photodynamic therapy, photosensitizer, porphyrins, magnetites, maghemite, crystalinity, magnetic seeds, nanoparticles, Description: Thesis (PhD (Organic Chemistry) -- University of Limpopo, 2011. 2011-01-01T00:00:00Z http://hdl.handle.net/10386/669 Title: The effects of hair relaxer treatment on the amino acid profile and surface characteristics of South African Negroid hair Authors: Ndlovu (Mamabolo), Thabisile Mavis Abstract: Surveys indicate that most South African origin women want long and straight hair (Mamabolo and Summers, 2006). Such women will therefore use a relaxer to straighten their hair. Many such preparations cause damage to the hair and scalp; hence identification of an effective and mild relaxer would be advantageous. This dissertation investigates South African origin hair structure and goes on to describe the effects of relaxers on South African origin hair. This work also analyses the effects of the lye and no-lye relaxers separately. The work was divided into two sections. The first section was the clinical study where two types of relaxers (‘lye’, a sodium hydroxide base relaxer and ‘no-lye’, a guanidine hydroxide base relaxer) were applied on the new outgrowth representing natural hair in a half-head study design of five South African origin female volunteers. Subjective (subject self-assessment) and objective (Researcher assessment) hair assessments were performed. The second section was the analysis of the hair samples by Reversed-Phase High Performance Liquid Chromatography (HPLC) using the Pico Tag as well as Electron Microscopy. There was no erythema detected in the clinical study on the scalp of any of the subjects post-application. Both the researcher and the subjects assessed the performance of the no-lye relaxer to be better than the lye relaxer in terms of straightness. The researcher also assessed the performance of the no-lye relaxer to be better than the lye relaxer in terms of softness, shininess, volume and dryness. The performance of the two types of relaxers was assessed to be the same by both the researcher and the subjects in terms of length and damage. There was a statistically significant (p< 0.1) decrease in the amount (g/100 g hair) of cystine after treatment compared to before treatment with both the lye relaxer (median [range]) (7.8 [2.5-9.9] vs. 9.1 [6.7-11.9]; p= 0.086) and the no-lye relaxer (4.0 [2.9-4.8] vs. 9.1 [6.7-11.9]; p= 0.005); this decrease was significantly greater (p= 0.086) for the no-lye relaxer. There was also a statistically significant decrease in the amount of lysine after treatment compared to before treatment with both the lye relaxer (2.0 [1.5-2.3] vs. 2.1 [2.0-2.6]; p= 0.082) and the no-lye relaxer (2.0 [1.5-2.2]; p= 0.036); this decrease was not significantly different (p= 0.920) for the two types of relaxer. No significant differences were found in the levels of the remaining 15 amino acids analysed. For all the subjects no physical evidence of hair damage was observable from the scanning electron microscopy images of the hair shafts and the cuticles. The longer wash-off time confirmed the claimed relative safety of ‘no-lye’ relaxers. The no-lye relaxer performed better overall than the lye relaxer in terms of the hair quality parameters assessed. A decrease in cystine levels is consistent with better performance in terms of hair straightness. The results from electron microscopy were not conclusive. Description: Thesis (MSc (Chemistry)) -- University of Limpopo, 2011. 2011-01-01T00:00:00Z http://hdl.handle.net/10386/632 Title: Zero divisors in banach algebras Authors: Mudau, Leonard Gumani Abstract: Summary not available Description: Thesis (M.Sc. (Mathematics) -- University of Limpopo, 2010 2010-01-01T00:00:00Z http://hdl.handle.net/10386/448 Title: Isolation and characterization of antibacterial and antioxidant compounds present in Combretum collinum subspecie suluense Authors: Ramurafhi, Thinashaka Ephraim Abstract: Isolation and characterization of antibacterial and antioxidant compounds present in Combretum collinum Sub specie Suluense Leaf extracts of six different plants, many of which are used by traditional healers, were screened for antibacterial activity. Ethyl acetate and Methanol extracts of Adina microcephaha, Combretum aurea, Combretum bracteosam, Combretum collinum, Filicium decipiens and Ficus moraceae were screened. Of these acetone extracted the highest mass of 118 mg from Filicium decipiens as compared to the extracts from the Adina microcephala, Combretum aurea, Combretum bracteosum, Combretum collinum and Ficus decipiens. Two unknown compounds were isolated, characterized and their minimum inhibitory concentrations were determined; compound A = 0.5689 mg/ml and compound E = 1.479 mg/ml. The chemical structure proposed for unknown compound A from Combretum collinum subsp suluense was determined by correlation of HNMR, FT-IR and GC-MS data. The chemical structure of compound E was not proposed because it was masked by a phthalate pollutant, the structure of which was confirmed by correlation of GC-MS, FT-IR and 1HNMR data. O O O O Proposed structure of compound from vial A Proposed structure of phthalate pollutant Description: Thesis (MSc (Chemistry))University of Limpopo, 2011. 2011-01-01T00:00:00Z