Abstract
Tuberculosis (TB) is a major global public health problem with high mortality and morbidity. In low-middle income countries (LMIC) a large number of respiratory symptomatic cases that require TB screening per year demands more accurate, fast and affordable testing for TB diagnostics. Sputum smear is the initial screening test in LMICs, however, its sensitivity is limited in patients with low sputum bacilli load. The same limitation is observed in the currently available molecular tests. We designed, standardized and evaluated an electrochemical biosensor that detects the highly specific DNA insertion element 6110 (IS6110). A PCR amplified DNA product is hybridized on the surface of the working electrode built on FTO-Glass with immobilized specific DNA probes, after which cyclic voltammetry is performed with an Ag/AgCl reference electrode and a platinum counter electrode. The response of the sensor was measured by the ratio (cathodic peak current of the hybridized sensor) / (cathodic peak current of the non-hybridized sensor). We tested the biosensor, using positive hybridization control sequences, genomic DNA extracted from M. tuberculosis strains and sputum of TB patients, and extracted DNA from the urine of healthy controls spiked with M. tuberculosis DNA. This biosensor was effective for the detection of M. tuberculosis DNA with a detection limit of 16 fM in sputum sample and 1 fM in spiked urine samples. The low cost and the relatively brief duration of the assay make this an important TB screening tool in the fight against tuberculosis.
Highlights
Tuberculosis (TB) continues to represent a problem in global public health
We show the design, standardization and evaluation of a fast, cheap and highly sensitive/specific, voltammetric electrochemical biosensor based on electrochemical detection of DNA hybridization for identification of the DNA sequence insertion element 6110 (IS6110) of Mycobacterium tuberculosis in both sputum and urine samples
With the addition of the Phenylene diisothiocyanate (PDITC), it was observed the presence of silicon and nitrogen
Summary
Tuberculosis (TB) continues to represent a problem in global public health. The World Health Organization (WHO) released a 2015 report that estimated around 9.6 million new cases of TB; including 1 million children. An electrochemical biosensor for the detection of Mycobacterium tuberculosis DNA
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