Biophysical Society Thematic Meeting - November 16-20, 2015

Biophysics in the Understanding, Diagnosis, and Treatment of Infectious Diseases Speaker Abstracts

Raman Biosensing for TB Diagnosis Jonathan Blackburn 1 , Keertan Dheda 1 , Makobetsa Khati 2 , David Wright 3 , Rick Haselton 3 , Christa Brosseau 4 . 1 University of Cape Town, Cape Town, South Africa, 4 St Mary's University, Halifax, NS, Canada. 3 Vanderbilt University, Nashville, TN, USA, 2 CSIR, Pretoria, South Africa, The global burden of tuberculosis (TB) today stands at ~9 million cases per annum worldwide. TB is currently the leading cause of mortality in South Africa and the causative agent, Mycobacterium tuberculosis (M.tb), is the most common opportunistic infection in HIV-infected persons; in South Africa today ~70% of new active TB case are HIV positive. Inaccurate diagnosis of TB disease and inability to monitor treatment response continues to be a confounder in disease transmission, patient mortality & morbidity, time to treatment initiation, and assessment of treatment response. Hence, new TB diagnostics designed for use at point-of-care in resource-poor settings represent a major unmet global health priority. In the absence of any reliable biomarker-based tests for TB, the gold standards for accurate diagnosis continue to rely on detection of whole pathogen, either via smear microscopy, culture or nucleic acid amplification. However, these each have problems associated with sensitivity, speed, cost and suitability for use a point of care in low resource settings. In this paper, we will therefore describe research aimed at developing a novel, hand-held DNA aptamer-based surface enhanced Raman scattering (SERS) biosensor able to give a quantitative, label-free spectroscopic readout on M.tb bacillary load, whilst simultaneously confirming pathogen identity in real time at point of care. To create the components of our platform, we have used both conventional and bead-based SELEX approaches to generate nM affinity DNA aptamers to M.tb cell surface markers. We have then developed several different, nanostructured, wide area noble metal surfaces and have combined these with electrochemical SERS techniques, the result being highly reproducible, quantitative SERS data. We have also developed a simple, field-deployable sample prep device for capture of M.tb bacilli from sputum and delivery on to our SERS biosensor. Results generated in each of these areas will be discussed.

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