Browsing by Author "Dunpall, Rekha"

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    An in vitro assessment of the potential toxicity of Cadmium Selenide nanoparticles
    (2012) Dunpall, Rekha; Shonhai, A.; Opoku, A.R.; Revaprasadu, N.
    Nanotechnology is steadily finding its application in all aspects of the consumer industry, science and engineering. At a relative pace Cadmium Selenide (CdSe) nanoparticles are gaining increased attention for their potential use in biomedical applications such as bioimaging of tissues, disease diagnosis and biological labelling due to its unique optical and electronic properties. Exposure of these particles to humans and other biological systems raise huge concerns with regards to their safety. In this study, water soluble cysteine capped CdSe nanocrystals, were prepared through a one pot green route method. The prepared CdSe nanocrystals were characterized using Transmission electron microscopy (TEM), High resolution transmission electron microscopy (HRTEM), Ultra violet spectroscopy (UV) and Photoluminescence (PL) analysis to establish the size, shape, dispersion, aggregation state, crystalline nature and optical properties of CdSe nanoparticles. The in vitro effects of CdSe nanoparticles on DNA stability, red blood cells (RBC’s) and blood platelets were evaluated. DNA was exposed to CdSe nanoparticles and its assessment on DNA stability was confirmed by agarose gel electrophoresis and spectrophotometry. Damage to DNA structure was observed at 200 μg/ml of CdSe. In vitro assays carried out on RBC damage included reducing power and chelating activity of iron. The results showed that the CdSe nanocrystals exhibited high reducing power and sufficient chelating activity, which would be able to impair the function of haemoglobin. CdSe nanoparticles promoted platelet aggregation in a dose dependent manner. Based on the findings of this study the biosafety of CdSe nanoparticles is not guaranteed and further studies need to be conducted to ascertain the safety of CdSe nanoparticles for possible use in biological systems.
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    The synthesis, characterisation and bioapplications of Novel Gold-Zinc Telluride Core-shell Nanoparticles
    (University of Zululand, 2016) Dunpall, Rekha; Revaprasadu, N.; Opoku, A.R.
    There is a growing demand for the development of innovative nano-drug delivery systems that can both target and improve cancer therapies more effectively than conventional chemotherapy. Novel Au-ZnTe nanoparticles was designed to support biocompatibility features that can be utilised for drug delivery and bio-imaging applications. Au, ZnTe and Au-ZnTe nanoparticles were synthesized and analysed for optical, morphological, crystalline and surface chemistry characterisation. Subsequent to materials characterisation, Au-ZnTe nanoparticles was evaluated for its potential toxicity using in vitro and in vivo systems. The nanoparticle was surface modified through conjugation with 5-FU and human epidermal growth factor antibody to facilitate targeted anti-cancer drug delivery, followed by the in vitro drug efficacy application. The Au-ZnTe nanoparticles displayed core-shell morphology with an average particle size of 7 ± 3.74 nm. The absorption wavelength of Au-ZnTe nanoparticles was dominated by the optical properties of gold and photoluminescence analysis showed that ZnTe dominated the emission properties of Au-ZnTe nanoparticles. Crystalline analysis displayed peaks attributed to both parental materials. The biosafety and cytotoxicity of these nanoparticles was established using normal human colon, mammary epithelial and cancer cells of breast, prostate and colon origin. Moreover, under certain conditions the particles expressed cytokines in low concentrations and induced an insignificant (20%) cytotoxic response when exposed to human peripheral blood mononuclear cells. Additionally systemic circulation of Au-ZnTe particles displayed no adverse effects in the blood, liver and kidney functions of female Sprague Dawley rats. TEM, FTIR, Zeta potential and optical measurements were performed to confirm the surface conjugation and interaction of 5-FU and EGF to Au-ZnTe nanoparticles. The in vitro anti-cancer therapeutic efficacy study was performed using the MTT cytotoxicity assay on breast cancer cells. The cytotoxicity studies have shown that all components in the 5-FU-EGF-Au-ZnTe nanoparticle formulation work synergistically to attack MCF7 cancer cells displaying 24.74 % increased efficacy than 5-FU at equivalent concentrations. Furthermore receptorligand mediated uptake of nano-drug formulations was demonstrated using 5-FU-Au-ZnTe. Several attempts were made to induce and develop a tumour model using Sprague Dawley rats and BALB/c mice. The presence of an external tumour mass was unsuccessful and therefore limited the ability to demonstrate the in vivo therapeutic efficacy of 5-FU-EGf-Au-ZnTe nanoparticles. These findings however lay a foundation for future work involving the synthesis and application of biocompatible nanoparticles that can support and improve current medical technologies. This study has generated valuable new knowledge that will help scientists within the field of biotechnology, nanomedicine, biochemistry and materials chemistry, to develop and optimize strategies for more efficient therapeutic application of nanomaterials.