Browsing by Author "Moabelo, Koena L"

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    Catalytic reduction of 4-nitrophenol and methylene blue by biogenic gold nanoparticles synthesized using Carpobrotus edulis fruit (sour fig) extract
    (SAGE Publications, 2022) Madiehe, Abram M; Moabelo, Koena L; Modise, Keletso
    Along with the increasing requirement for efficient organic conversions using green chemistry, there is a need to develop highly efficient and eco-friendly catalytic reaction systems. Gold nanoparticles (AuNPs)-based nanocatalysts are promising candidates for the reduction of environmental pollutants, such as nitroaromatics and dyes. This study reports on the green synthesis of AuNPs using Carpobrotus edulis (C. edulis) fruit aqueous extract (CeFE) and their catalytic activities. The CeFE induced rapid reduction of gold (III) salt to form monodispersed and spherical AuNPs, with a core and hydrodynamic sizes of 40 and 108.7 nm, respectively. CeFE alone had no effect on 4-nitrophenol, whereas incubation with methylene blue (MB) caused reduction of the peak at 665 nm. Addition of CeFE-AuNPs in the presence of NaBH4, caused the reduction of 4-nitrophenol to 4-AP, and MB to leucoMB within 10 min. These reactions followed the pseudo first-order kinetics. Therefore, biogenic CeFE-AuNPs could be used for the elimination of noxious environmental pollutants.
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    Nanotechnology-based strategies for effective and rapid detection of sars-cov-2
    (MDPI, 2021) Moabelo, Koena L; Martin, Darius R; Fadaka, Adewale O; Sibuyi, Nicole R. S.; Meyer, Mervin
    The coronavirus disease 2019 (COVID-19) pandemic has gained worldwide attention and has prompted the development of innovative diagnostics, therapeutics, and vaccines to mitigate the pandemic. Diagnostic methods based on reverse transcriptase-polymerase chain reaction (RT-PCR) technology are the gold standard in the fight against COVID-19. However, this test might not be easily accessible in low-resource settings for the early detection and diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The lack of access to well-equipped clinical laboratories, requirement for the high level of technical competence, and the cost of the RT-PCR test are the major limitations. Moreover, RT-PCR is unsuitable for application at the point-of-care testing (PoCT) as it is time-consuming and lab-based. Due to emerging mutations of the virus and the burden it has placed on the health care systems, there is a growing urgency to develop sensitive, selective, and rapid diagnostic devices for COVID-19. Nanotechnology has emerged as a versatile technology in the production of reliable diagnostic tools for various diseases and offers new opportunities for the development of COVID-19 diagnostic systems. This review summarizes some of the nano-enabled diagnostic systems that were explored for the detection of SARS-CoV-2. It highlights how the unique physicochemical properties of nanoparticles were exploited in the development of novel colorimetric assays and biosensors for COVID-19 at the PoCT. The potential to improve the efficiency of the current assays, as well as the challenges associated with the development of these innovative diagnostic tools, are also discussed.