Ronen Fogel

Antioxidant and Iron-Binding Properties of Curcumin, Capsaicin, and S-Allylcysteine Reduce Oxidative Stress in Rat Brain Homogenate

Research demonstrates that antioxidants and metal chelators may be of beneficial use in the treatment of neurodegenerative diseases, such as Alzheimers disease (AD). This study investigated the antioxidant and metal-binding properties of curcumin, capsaicin, and S-allylcysteine, which are major components found in commonly used dietary spice ingredients turmeric, chilli, and garlic, respectively. The DPPH assay demonstrates that these compounds readily scavenge free radicals. These compounds significantly curtail iron- (Fe2+) and quinolinic acid (QA)-induced lipid peroxidation and potently scavenge the superoxide anion generated by 1 mM cyanide in rat brain homogenate. The ferrozine assay was used to measure the extent of Fe2+ chelation, and electrochemistry was employed to measure the Fe3+ binding activity of curcumin, capsaicin, and S-allylcysteine. Both assays demonstrate that these compounds bind Fe2+ and Fe3+ and prevent the redox cycling of iron, suggesting that this may be an additional method through which these agents reduce Fe2+-induced lipid peroxidation. This study demonstrates the antioxidant and metal-binding properties of these spice ingredients, and it is hereby postulate that these compounds have important implications in the prevention or treatment of neurodegenerative diseases such as AD.

Developing Biosensors in Developing Countries: South Africa as a Case Study

A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental research into the signal transduction method, using model biorecognition elements, in line with international trends. Other research in this field is spread across several areas including: the application of nanotechnology; the identification and validation of biomarkers; development and testing of biorecognition agents (antibodies and aptamers) and design of electro-catalysts, most notably metallophthalocyanine. Biosensor targets commonly featured were pesticides and metals. Areas of regional import to sub-Saharan Africa, such as HIV/AIDs and tuberculosis diagnosis, are also apparent in a review of the available literature. Irrespective of the targets, the challenge to the effective deployment of such sensors remains shaped by social and economic realities such that the requirements thereof are for low-cost and universally easy to operate devices for field settings. While it is difficult to disentangle the intertwined roles of national policy, grant funding availability and, certainly, of global trends in shaping areas of emphasis in research, most notable is the strong role that nanotechnology, and to a certain extent biotechnology, plays in research regarding biosensor construction. Stronger emphasis on collaboration between scientists in theoretical modelling, nanomaterials application and or relevant stakeholders in the specific field (e.g., food or health monitoring) and researchers in biosensor design may help evolve focused research efforts towards development and deployment of low-cost biosensors.

Metallophthalocyanine/carbon nanotube hybrids: extending applications to microbial fuel cells

Pioneering work by Nyokong and others have highlighted the potential benefits for improved electron transfer processes and catalysis of hybrid configurations of metallophthalocyanines with carbon nanotubes. Here we examine the practical application of such hybrid configurations in an Enterobacter cloacae microbial fuel cell. Electrochemical investigations at glassy carbon electrodes (GCEs) showed that FePc and FePc:multiwalled carbon nanotube (MWCNT) hybrid surface modifications display significant oxygen reduction reaction electrocatalytic properties compared to either MWCNT-modified or bare GCE surfaces throughout acidic- to moderately-alkaline pHs. Significant stabilization of the current response at FePc:MWCNT surfaces are notable throughout the pH range, compared to GCE surfaces modified with FePc alone. Corresponding results were obtained for surface modifications of bare carbon paper (BCP) cathodes in a microbial fuel cell where power density increases were observed in the order: Pt > FePc:MWCNT > FePc > MWCNT > BCP. A synergistic combination of simple treatments such as increased ionic strength (300 mM NaCl), temperature (35 °C), and agitation of the anode chamber in this MFC configuration increased the power density to 2.5 times greater than that achieved at platinised cathode configurations under non-optimised conditions, achieving peak power densities of 212 mW.m-2. The long-term stability of the MFC was assessed over 55 days. Surprisingly, the majority of signal loss over extended MFC operation was attributed, in this study, to fouling of the Nafion® PEM membrane rather than either leaching/fouling of the catalysts from the electrodes or nutrient depletion in the anode over the time periods examined.

Comparison of fluorophore and peroxidase labeled aptamer assays for MUC1 detection in cancer cells

Aptamers hold great promise for cancer diagnosis and therapy. Several biosensors incorporate aptamers as biorecognition elements for tumor markers although few evaluate their detection in a native conformation and cellular micro-environment. In this study, fluorophore and peroxidase labeled aptamer configurations were compared for the detection of MCF7 breast and SW620 colon cancer cell lines expressing the tumor marker MUC1. Fluorescence based detection showed selective binding to the cell lines relative to a nonbinding control sequence with sequence specific binding differences between MUC1 aptamers accredited to variation in the glycosylation state of expressed MUC1. The peroxidase labeled assay showed high detection sensitivity although low binding specificity was observed for the MUC1 aptamers to the cell lines. Results suggest that aptamers susceptible to non specific binding to cells may limit the applicability of enzymatic amplification to improve aptasensor sensitivity.