Magister Scientiae - MSc (Biotechnology)

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https://hdl.handle.net/10566/13204

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Browsing by Author "Antunes, Edith"

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    The antimicrobial activity of zinc oxide nanoparticles synthesized with plant extracts against Staphylococcus aureus
    (University of the Western Cape, 2019) Kriek, Gisela; Antunes, Edith
    Nanoparticles using a green synthesis production method is of increasing interest for biomedical applications. Zinc oxide is currently used in medicinal and cosmetic formulations, and zinc oxide nanoparticles have potential in biomedical applications. Antibiotic-resistant bacterial infections are of growing concern globally, and novel antimicrobial agents are drastically needed. In this work, zinc oxide nanoparticles were synthesized using Calendula officinalis flowers aqueous extract and zinc nitrate hexahydrate using a single-pot green synthesis approach. The synthesized particles were calcined and characterised using UV-Vis spectrophotometry, Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Fourier-Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance Imaging (NMR). Quasi-spherical, hexagonal phase zinc oxide nanoparticles with core size <10nm according to TEM and average size of ~53nm according to XRD were successfully synthesized. The particles tended towards agglomeration. Antioxidant assays were run to determine the reducing power, antioxidant activity, and presence of polyphenols in the final products. The final product possessed antioxidant activity, polyphenols and had reducing power, confirming the constituents from Calendula officinalis playing a role in the reduction of the zinc ions and capping of the zinc oxide nanoparticles. Minimum inhibitory concentration of the samples by tube dilution was conducted to determine potential of the samples as antimicrobial agent against methicillin-resistant Staphylococcus aureus, using Clindamycin as control. Results of antimicrobial studies indicate the need for investigation of MIC using a variety of concentrations of the samples, and a variety of solvents, in order to determine exact MIC values. Further work is needed to improve the methodology to obtain particles that have a narrow size distribution, that are well dispersed, and are of higher concentration to be considered for antimicrobial use in the biomedical field.
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    Green Synthesis and characterization of gold Nanoparticles using Green Alga Ulva Lactuca and evaluation of their Catalytric Role
    (University of the Western Cape, 2016) Mukhoro, Ofhani Christopher; Antunes, Edith
    Nanoparticles synthesized using typical chemical procedures have associated environmental risks because of the use of hazardous chemicals. With the ever-increasing potential application for nanomaterials, there is a growing need to develop new synthetic procedures for nanomaterials which are non-toxic and eco-friendly. This study presents, as a first step, the screening of the aqueous extracts of several seaweeds in order to assess their ability to produce gold nanoparticles (AuNPs). Eleven aqueous extracts were screened for the synthesis of AuNPs and where AuNPs were formed, these were further characterized using UV-vis spectroscopy and HRTEM primarily. Three of the eleven aqueous extracts shown to produce AuNPs were extracts obtained from brown algae. The total antioxidant and total reducing power contents, as well as the DPPH radical scavenging abilities for these extracts were determined and related to their ability to produce the NPs. The AuNPs were found to be of various shapes and sizes including spheres, rods and triangles, with sizes ranging from 20 nm to 200 nm.