Winfred G. Aker

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Nanoparticles (NPs), including nanometal oxides, are being used in diverse applications such as medicine, clothing, cosmetics and food. In order to promote the safe development of nanotechnology, it is essential to assess the potential adverse health consequences associated with human exposure. The liver is a target site for NP toxicity, due to NP(More)
In this paper we describe how utilization of low molecular weight alginate-derived oligosaccharide (ADO) and chito-oligosaccharide (COS) in conjunction with antibiotics, could more effectively inhibit the growth of wild-type and resistant Pseudomonas aeruginosa. Inhibition is effected by modulating the bacteria's quorum sensing (QS) system, thus regulating(More)
Malathion inhibits the critical body enzyme, acetylcholinesterase (AChE). This capability requires that malathion should first be converted to malaoxon to become an active anticholinesterase agent. Conversion can be caused by oxidation in mammals, insects, plants, and in sunlight. In this study, the effects of malathion and malaoxon on catfish Ictalurus(More)
The role of light on the acute toxicities of S-doped and Sigma TiO2 nanoparticles in zebrafish was studied. Metrics included mortality for both, and rheotaxis dysfunction and DNA damage for S-doped only. It was found that the acute toxicity of S-TiO2 nanoparticles was enhanced by simulated sunlight (SSL) irradiation (96-h LC50 of 116.56 ppm) and exceeded(More)
In this report, we critically reviewed selected intrinsic physicochemical properties of engineered nanomaterials (ENMs) and their role in the interaction of the ENMs with the immediate surroundings in representative aquatic environments. The behavior of ENMs with respect to dynamic microenvironments at the nano-bio-eco interface level, and the resulting(More)
Assessment of C(60) nanotoxicity requires a variety of strategies for dispersing it into biological systems. Our objective was to determine organic solvent/surfactant combinations suitable for this purpose. We used Escherichia coli (ATCC# 25254) to determine the cytotoxicity of C(60) in solvents at concentrations up to 100 ppm. In this preliminary study we(More)
The seaweed Ulva prolifera, distributed in inter-tidal zones worldwide, contains a large percentage of cellulosic materials. The technical feasibility of using U. prolifera residue (UPR) obtained after extraction of polysaccharides as a renewable energy resource was investigated. An environment-friendly and economical pretreatment process was conducted(More)
Many biomolecules contain photoactive reducing agents, such as reduced nicotinamide adenine dinucleotide (NADH) and 6-thioguanine (6-TG) incorporated into DNA through drug metabolism. These reducing agents may produce reactive oxygen species under UVA irradiation or act as electron donors in various media. The interactions of C60 fullerenes with biological(More)
Two different degradases from Alteromonas sp. A321 for polysaccharides from Enteromorpha prolifera (DPE-L and DPE-P) were purified to homogeneity. The molecular weights of purified DPE-L and DPE-P were 75.2 and 102.5 kDa, respectively, and their internal sequences were analysed by LC-MS-MS. The enzymes exhibited an optimum temperature of 30-40 °C (DPE-L)(More)
Titanium dioxide nanoparticles (TiO2 NPs) are among the most widely manufactured nanomaterials on a global scale. However, prudent and vigilant surveillance, incumbent upon the scientific community with the advent of new technologies, has revealed potentially undesirable effects of TiO2 NPs on biological systems and the natural environment during their(More)