Browsing by Author "Meyer, M"

Now showing 1 - 8 of 8
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    Broad Spectrum Anti-Bacterial Activity and Non-Selective Toxicity of Gum Arabic Silver Nanoparticles
    (MDPI, 2022-02-04) Fadaka, AO; Meyer, S; Ahmed, O; Geerts, G; Madiehe, MA; Meyer, M; Sibuyi, NRS
    Silver nanoparticles (AgNPs) are the most commercialized nanomaterials and presumed to be biocompatible based on the biological effects of the bulk material. However, their physico-chemical properties differ significantly to the bulk materials and are associated with unique biological properties. The study investigated the antimicrobial and cytotoxicity effects of AgNPs synthesized using gum arabic (GA), sodium borohydride (NaBH4), and their combination as reducing agents. The AgNPs were characterized using ultraviolet-visible spectrophotometry (UV-Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The anti-bacterial activity was assessed using agar well diffusion and microdilution assays, and the cytotoxicity effects on Caco-2, HT-29 and KMST-6 cells using MTT assay. The GA-synthesized AgNPs (GA-AgNPs) demonstrated higher bactericidal activity against all bacteria, and non-selective cytotoxicity towards normal and cancer cells. AgNPs reduced by NaBH4 (C-AgNPs) and the combination of GA and NaBH4 (GAC-AgNPs) had insignificant anti-bacterial activity and cytotoxicity at ≥50 µg/mL. The study showed that despite the notion that AgNPs are safe and biocompatible, their toxicity cannot be overruled and that their toxicity can be channeled by using biocompatible polymers, thereby providing a therapeutic window at concentrations that are least harmful to mammalian cells but toxic to bacteria.
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    Developing a lateral flow device for the detection of novel breast cancer biomarkers
    (University of the Western Cape, 2023) Tejada, Aaron; Meyer, M
    Breast cancer is the most prevalent malignancy and one of the leading causes of death in women worldwide. Delayed diagnosis of breast cancer greatly reduces the effectiveness of treatment and is considered one of the major contributing factors to its high mortality rate. Cancer treatment is most effective during the early stages of the disease, therefore the earlier that cancer is detected, the greater the chance for survival. Currently, breast cancer screening relies largely on imaging techniques such as mammography and magnetic resonance imaging (MRI) which lack sensitivity and specificity; and are both invasive, cost-intensive and are often not easily accessible to patients in low-income countries.
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    An investigation into the antimicrobial and immune modulatory effects of Sutherlandia frutescens and Salvia africana-lutea extracts and their respective biogenic nanoparticles
    (University of the Western Cape, 2020) Dube, Phumuzile; Meyer, M
    The prevalence of cancer and antibiotic-resistant microbes has led to the necessity of affordable, efficacious, non-toxic and easily accessible therapeutic approaches. There is numerous anecdotal evidence that African Traditional Medicines (ATM), in particular medicinal plants, have anticancer, antimicrobial and “immune booster” activities. The interaction of medicinal plants with the immune system could be a great asset in drug discovery. Two South African plants, Sutherlandia frutescens (cancer bush) and Salvia africana-lutea (brown dune sage) have been associated with a long history of traditional use in the treatment of a variety of ailments including cancer and infections. Additionally, the complexity of phytochemicals present in medicinal plants has led to their utilization in the synthesis of biogenic nanoparticles. Synthesis of colloidal biogenic nanoparticles using plant extracts could possibly enhance the bioactivity of the synthesising phytochemicals. The improved bioactivity of synthesised biogenic nanoparticles is probably due to the enhanced stability of synthesising phytochemicals within the nanoparticles, and increased surface area of nanoparticles giving rise to an improved delivery of beneficial phytochemicals to target cells.
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    The macrophage response to mycobacterium tuberculosis and opportunities for autophagy inducing nanomedicines for Tuberculosis therapy
    (Frontiers Media S.A., 2021) Meyer, M; Maphasa, R.E; Dube, A
    The major causative agent of tuberculosis (TB), i.e., Mycobacterium tuberculosis (Mtb), has developed mechanisms to evade host defense responses and persist within host cells for prolonged periods of time. Mtb is also increasingly resistant to existing anti-TB drugs. There is therefore an urgent need to develop new therapeutics for TB and host directed therapies (HDTs) hold potential as effective therapeutics for TB. There is growing interest in the induction of autophagy in Mtb host cells using autophagy inducing compounds (AICs). Nanoparticles (NPs) can enhance the effect of AICs, thus improving stability, enabling cell targeting and providing opportunities for multimodal therapy. In this review, we focus on the macrophage responses to Mtb infection, in particular, the mechanistic aspects of autophagy and the evasion of autophagy by intracellular Mtb. Due to the overlap between the onset of autophagy and apoptosis; we also focus on the relationship between apoptosis and autophagy.
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    Multifunctional Gold Nanoparticles for Improved Diagnostic and Therapeutic Applications: A Review
    (Springer Open, 2021) Sibuyi, NR; Moabelo, K; Meyer, M
    The medical properties of metals have been explored for centuries in traditional medicine for the treatment of infections and diseases and still practiced to date. Platinum-based drugs are the first class of metal-based drugs to be clinically used as anticancer agents following the approval of cisplatin by the United States Food and Drug Administration (FDA) over 40 years ago. Since then, more metals with health benefits have been approved for clinical trials. Interestingly, when these metals are reduced to metallic nanoparticles, they displayed unique and novel properties that were superior to their bulk counterparts. Gold nanoparticles (AuNPs) are among the FDA-approved metallic nanoparticles and have shown great promise in a variety of roles in medicine. They were used as drug delivery, photothermal (PT), contrast, therapeutic, radiosensitizing, and gene transfection agents. Their biomedical applications are reviewed herein, covering their potential use in disease diagnosis and therapy. Some of the AuNP-based systems that are approved for clinical trials are also discussed, as well as the potential health threats of AuNPs and some strategies that can be used to improve their biocompatibility. The reviewed studies offer proof of principle that AuNP-based systems could potentially be used alone or in combination with the conventional systems to improve their efficacy.
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    Plant Extract-Synthesized Silver Nanoparticles for Application in Dental Therapy
    (MDPI, 2022-02-08) Ahmed, Omnia; Sibuyi, NRS; Fadaka, AO; Madiehe, MA; Maboza, E; Meyer, M; Geerts, G
    Oral diseases are the most common non-communicable diseases in the world, with dental caries and periodontitis causing major health and social problems. These diseases can progress to systematic diseases and cause disfigurement when left untreated. However, treatment of oral diseases is among the most expensive treatments and often focus on restoration of form and function. Caries prevention has traditionally relied on oral hygiene and diet control, among other preventive measures. In this paper, these measures are not disqualified but are brought into a new context through the use of nanotechnology-based materials to improve these conventional therapeutic and preventive measures. Among inorganic nanomaterials, silver nanoparticles (AgNPs) have shown promising outcomes in dental therapy, due to their unique physicochemical properties and enhanced anti-bacterial activities. As such, AgNPs may provide newer strategies for treatment and prevention of dental infections. However, numerous concerns around the chemical synthesis of nanomaterials, which are not limited to cost and use of toxic reducing agents, have been raised. This has inspired the green synthesis route, which uses natural products as reducing agents. The biogenic AgNPs were reported to be biocompatible and environmentally friendly when compared to the chemically-synthesized AgNPs. As such, plant-synthesized AgNPs can be used as antimicrobial, antifouling, and remineralizing agents for management and treatment of dental infections and diseases.
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    The secret life of doors
    (University of the Western Cape, 2021) Meyer, M; Moolman, K
    This mini-thesis explores the poetic journey toward the subconscious images of an individual’s memory. It comprises a collection of 35 authentic poems and a reflective essay that examines the uncovering during the creative process. The project explores opposites and dualities of the mindroom and examines the concept of a hypothetical door as a mechanism to reveal archetypal patterns through memory.
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    Synthesis, characterization and anticancer activity of new 2-acetyl-5-methyl thiophene and cinnamaldehyde thiosemicarbazones and their palladium(II) complexes
    (Elsevier S.A., 2021) Nyawade, E.A; Sibuyi, N.R.S; Meyer, M
    New thiosemicarbazone (TSC) ligands, AMT-C[dbnd]N-TSCH (L1), AMT-C[dbnd]N-TSC(CH3) (L2), CIN-C[dbnd]N-TSCH (L3) and CIN-C[dbnd]N-TSC(CH3) (L4) (AMT = 2-acetyl-5-methylthiophene, TSCH = thiosemicarbazide, TSC(CH3) = 4-methyl-3-thiosemicarbazide, CIN = cinnamaldehyde) were synthesized by condensation reaction. The reaction of [PdCODCl2] with the ligands L1, L2 and L4in the ratio 1:1 yielded complexes [Pd(L1)Cl] (C1), [Pd(L2)Cl2] (C2), and [Pd(L4)2Cl2] (C4) respectively (COD = 1,5-cyclooctadiene). The reaction of [Pd(COD)Cl2] with CIN-C[dbnd]N-TSCH (L3) in 1:2 metal to ligand ratio yielded the complex [Pd(L3)2] (C3). The ligands and the complexes were characterized by UV–Vis, FT-IR, NMR, elemental analysis and conductivity measurements. The ligand L1 coordinated to the metal in a tridentate fashion while L2, L3 and L4 coordinated in a bidentate fashion. The ligands L1 and L3 coordinated to the metal as thiol anions while ligand L4 coordinated via the thione sulphur. Conductivity measurements of the metal complexes in dimethyl sulfoxide showed that the chloride ions complexes C1, C2 and C4 are within the coordination spheres.