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Research Publications (Applied Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/213

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Subject: search.filters.subject.Antibacterial

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    Recent advances on metal oxide based nano-photocatalysts as potential antibacterial and antiviral agents
    (MDPI AG, 2022) Prakash, Jai; Krishna, Suresh Babu Naidu; Kumar, Promod; Kumar, Vinod; Ghosh, Kalyan S.; Swart, Hendrik C.; Bellucci, Stefano; Cho, Junghyun
    Photocatalysis, a unique process that occurs in the presence of light radiation, can potentially be utilized to control environmental pollution, and improve the health of society. Photocatalytic removal, or disinfection, of chemical and biological species has been known for decades; however, its extension to indoor environments in public places has always been challenging. Many efforts have been made in this direction in the last two–three years since the COVID-19 pandemic started. Furthermore, the development of efficient photocatalytic nanomaterials through modifications to improve their photoactivity under ambient conditions for fighting with such a pandemic situation is a high research priority. In recent years, several metal oxides-based nano-photocatalysts have been designed to work efficiently in outdoor and indoor environments for the photocatalytic disinfection of biological species. The present review briefly discusses the advances made in the last two to three years for photocatalytic viral and bacterial disinfections. Moreover, emphasis has been given to the tailoring of such nano-photocatalysts in disinfecting surfaces, air, and water to stop viral/bacterial infection in the indoor environment. The role of such nano-photocatalysts in the photocatalytic disinfection of COVID-19 has also been highlighted with their future applicability in controlling such pandemics.
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    Biocatalytic and biological activities of cassia occidentalis mediated silver nanoparticles
    (College of Graduate Studies, Walailak University, 2022-01-01) Singh, Shashika; Mohanlall, Viresh
    Silver nanoparticles (AgNPs) were synthesized using the leaf extracts from Cassia occidentalis. The reactions were marked by a distinct colour change and the formation of AgNPs was monitored by measuring the UV-Vis spectra. The morphology and crystalline phase of the metal nanoparticles were determined using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray analysis (EDX) and Fourier-Transform-Infrared Spectroscopy (FTIR). The biocatalytic activity of the AgNPs against nitrifying compounds was determined using 4-nitrophenol and 4-nitroalanine. The biological screening involved analyzing the AgNPs effectiveness against gram-negative and gram-positive bacteria (Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus cereus and Enterococcus faecalis). The AgNPs displayed minimal inhibition at low concentrations ranging from 25 to 50 μg/mL. The toxicity of the AgNPs was tested using the brine shrimp assay and was observed as non-toxic with a nearly zero mortality rate. The AgNPs exhibited an antioxidant potential of 70.90 % inhibition at 1000 µg/mL. C. occidentalis is noted as a potential bioresource for synthesizing AgNPs with applications as antibacterial, antioxidant and biocatalytic agents. HIGHLIGHTS The addition of Ag nanoparticles to C. occidentalis plant extracts resulted in the formation of AgNPs-C. occidentalis complexes The AgNPs-C. occidentalis complexes were characterized using Transmission Electron Microscopy, Scanning Electron Microscopy with EDX, UV-Vis spectrophotometry and IR spectroscopy These AgNPs-C. occidentalis complexes were very stable and showed antibacterial activity against a range of tested gram-positive and gram-negative bacteria at low doses, thus proving to be good antimicrobial agents The AgNPs-C. occidentalis complexes showed higher scavenging activity than leaf extracts of C. occidentalis. The AgNPs have increased catalytic ability for the reduction of 4-nitrophenol and 4-nitroalanine after a 30 min time interval GRAPHICAL ABSTRACT
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    Biomedical applications and toxicity of nanosilver : a review
    (Ituta e-solutions, 2015-12) Krishna, Suresh Babu Naidu; Govender, Patrick; Adam, Jamila Khatoon
    Nanotechnology is a promising arena for generating new applications in medicine. It is advancing rapidly due to the great progress achieved in various fileds including electronics, machanics, cosmetics, food, etc. In order to successfully bifunctionalise nanoparticles for a given biomedical application, a wide range of chemical, physical and biological factors have to be taken into account. Silver nanoparticles (AgNPs) exhibit strong antibacterial activity owing to their large surface to volume ratios and crystallographic surface structure. Nanosilver particles have been widely used in a range of biomedical applications including diagnosis, treatment, medical device coatings, drug delivery and personal health care products. With the growing application of nanosilver particles in medical contexts, it is becoming necessary for a better understanding the mechanisms of action, biological interactions and their potential toxicity on exposure. This review aims to provide critical assess-ment of the current understanding of antibacterial activity, biomedical applications and toxicity of silver nanoparticles.