Investigations into novel electrochemical technology for boar taint detection and vitamin analysis

This thesis presents the evaluation of the novel electrochemical sensor and biosensor technology developed for the direct analysis of boar taint compounds in adipose tissue (European Patent 2966441). Gas chromatographic methods and extraction procedures were adapted for the evaluation of the novel sensor technology. The methodologies for the non-destructive sensor technology were evaluated by analysing stored porcine adipose tissue, the samples were subsequently analysed by the destructive gas-chromatographic methodologies for comparison. The results from two analytical methods correlated well for both compounds of interest in a laboratory environment. Consequently, the sensor and biosensor were integrated into a dual system and evaluated in the laboratory. The dual electrochemical system was optimised for simultaneous measurement. The prototype was taken to an abattoir, the subcutaneous adipose tissue of carcasses were analysed online then the section was removed and stored before analysis via the laboratory based extraction and gas-chromatographic analysis procedures. The quantitative data correlation indicates that this technology is viable for its proposed industrial application.Other endogenous compounds in boar tissue were also identified prior to sample analysis during a literature review. The reported electrochemical behaviour and concentration ranges of these compounds were used to identify compounds which could result in the novel technology displaying false positive or false negative responses. During this preliminary investigation the identified compounds did not respond at the novel technology in a similar manner to the analytes of interest under physiological conditions. However, under basic electrolyte conditions an anodic response for 3 B-vitamin compounds was observed. As a secondary study to the boar taint analysis a simple voltammetric assay was developed to exploit this behaviour and applied to the analysis of a food product and pharmaceutical supplement

A novel electroanalytical approach to the measurement of B vitamins in food supplements based on screen-printed carbon sensors

© 2017 Elsevier B.V. This paper describes the development of a novel electrochemical assay for the measurement of water-soluble vitamins in food and pharmaceutical products. The optimum conditions for the determination of vitamin B1 (thiamine), B2 (riboflavin) and B6 (pyridoxine) in phosphate buffer were established using cyclic voltammetry in conjunction with screen printed carbon electrodes (SPCEs). The optimum current response for all three vitamins was achieved in 0.1 M phosphate buffer pH 11 using an initial potential of −1.0 V. Using square wave voltammetry, the linear ranges for thiamine, riboflavin, and pyridoxine were found to be: 15–110 µg/ml, 0.1–20 µg/ml, and 2–80 µg/ml respectively. The application of the method to a commercial food product yielded a recovery of 95.78% for riboflavin, with a coefficient of variation (CV) of 3.38% (n = 5). The method was also applied to a multi-vitamin supplement for the simultaneous determination of thiamine, riboflavin and pyridoxine. In both cases only simple dilution with buffer followed by centrifugation was required prior to analysis. The resulting square wave voltammetric signals were completely resolved with Ep values of −0.7 V, +0.2 V, and +0.6 V respectively. The recoveries determined for the vitamin B complex in a commercial supplement product were found to be 110%, 114%, and 112% respectively (CV = 7.14%, 6.28%. 5.66% respectively, n = 5)

An electrocatalytic screen-printed amperometric sensor for the selective measurement of thiamine (Vitamin B1) in food supplements

An electrocatalytic screen-printed sensor has been investigated for the measurement of the biologically important biomolecule vitamin B1 (thiamine) for the first time in food supplements. Under basic conditions, the vitamin was converted to its electrochemically active thiolate anion species. It was shown that an electrocatalytic oxidation reaction occurred with the screen-printed carbon electrode containing the mediator cobalt phthalocyanine (CoPC-SPCE). This had the advantage of producing an analytical response current at an operating potential of 0 V vs. Ag/AgCl compared to +0.34 V obtained with plain SPCEs. This resulted in improved selectivity and limit of detection. Detailed studies on the underlying mechanism occurring with the sensor are reported in this paper. A linear response was obtained between 0.1 and 20 µg mL −1 , which was suitable for the quantification of the vitamin in two commercial products containing vitamin B1. The mean recovery for a multivitamin tablet with a declared content of 5 mg was 101% (coefficient of variation (CV) of 9.6%). A multivitamin drink, which had a much lower concentration of vitamin B1 (0.22 mg/100 mL), gave a mean recovery of 93.3% (CV 7.2%). These results indicate that our sensor holds promise for quality control of food supplements and other food types

Microbiome Composition and Function Drives Wound-Healing Impairment in the Female Genital Tract

The mechanism(s) by which bacterial communities impact susceptibility to infectious diseases, such as HIV, and maintain female genital tract (FGT) health are poorly understood. Evaluation of FGT bacteria has predominantly been limited to studies of species abundance, but not bacterial function. We therefore sought to examine the relationship of bacterial community composition and function with mucosal epithelial barrier health in the context of bacterial vaginosis (BV) using metaproteomic, metagenomic, and in vitro approaches. We found highly diverse bacterial communities dominated by Gardnerella vaginalis associated with host epithelial barrier disruption and enhanced immune activation, and low diversity communities dominated by Lactobacillus species that associated with lower Nugent scores, reduced pH, and expression of host mucosal proteins important for maintaining epithelial integrity. Importantly, proteomic signatures of disrupted epithelial integrity associated with G. vaginalis-dominated communities in the absence of clinical BV diagnosis. Because traditional clinical assessments did not capture this, it likely represents a larger underrepresented phenomenon in populations with high prevalence of G. vaginalis. We finally demonstrated that soluble products derived from G. vaginalis inhibited wound healing, while those derived from L. iners did not, providing insight into functional mechanisms by which FGT bacterial communities affect epithelial barrier integrity

Increased levels of inflammatory cytokines in the female reproductive tract are associated with altered expression of proteases, mucosal barrier proteins, and an influx of HIV-susceptible target cells.

CAPRISA, 2016.Abstract available in pdf