Bioanalytical methods encompassing label-free and labeled tuberculosis aptasensors: A review

The high incidence of tuberculosis (TB) infection is of great concern world-wide. The traditional TB diagnostic techniques are not ideal for TB diagnosis in resource-poor countries. This is due to their high complexity, expensive nature, long time duration, poor sensitivity and specificity, as well as their requirement for sophisticated laboratories with special biosafety conditions. These limitations are major factors contributing to late diagnosis of TB and its continuous persistence. Biosensors offer several advantages as diagnostic tool due to their independence on Mycobacterium tuberculosis, simplicity, low-cost, high sensitivity and specificity. Likewise, the increasing interest on aptamers as biorecognition elements in biosensor application lies in their ease of synthesis and modification, chemical and thermal stability, low-cost, and high sensitivity and specificity towards their targets. Several research works have been done and many more are still on-going on fabrication and application of aptasensors for TB diagnosis. This review summarizes the label-free and label-based electrochemical, piezoelectric and optical aptasensors for TB diagnosis published in the last decade. It focuses on their various aptamer sequence modifications, assay formats, sensitivities, nanomaterial and enzyme-based signal amplification strategies, and the possibility of miniaturization and automation using microfluidic devices.