Electrochemical detection of Mycobacterium tuberculosis using Screen Printed Electrodes

Abstract

Tuberculosis (TB) is a major public health problem around the globe. The mortality rate of TB stands at around 1.5 million deaths with 200,000 deaths reported in HIV positive individuals. The classic microscopic tests for TB include fluorescent staining and Ziel-Neelsen staining. Microscopy is relatively easy to carry out but has a low sensitivity. Similarly, culturing of the TB is carried out in liquid or solid media. However, culturing typically takes 14-37 days and requires specialized personnel and a biosafety level 2 (BSL-2) facility. DNA assays utilizing Polymerase Chain Reaction (PCR) can be used for amplification of DNA strands which can later be analyzed by gel electrophoresis for the diagnosis. Recent advances in the field of biosensors have made them a promising tool for the rapid diagnosis of several infections with great reduction in the cost and the lab requirements for performing such tests. The basic principle for an electrochemical biosensor is that the reaction between a biomolecule and the target analyte causes change in electrical properties of the electrolyte solution which can be measured by electrical potential or current. DNA sensing is particularly easy by using such reaction due to the conductive properties of DNA hybridization event. Electrochemical sensors have a low-cost operation, ability to analyze a plethora of analytes, rapid sample processing, and a potential to be miniaturized which make them desirable sensing platforms for infectious diseases. Typically, bio-recognition element is immobilized on the surface of working electrode for it to act as a transducer on the binding of target analyte. In this work, we have utilized amino modified probes specific for the detection of IS6110. The hydroxyapatite provides the stability as well as the binding matrix for the probe. Genomic DNA is extracted from raw TB sputum samples and amplified by PCR. The characterization and confirmation of detection was done by electrochemistry.