New Sandwich Biosensor Developed for Tuberculosis Diagnosis and Screening

Researchers have developed a system that could quickly and reliably identify people infected with Mycobacterium tuberculosis and simultaneously differentiate from those who have received the bacillus Calmette-Guerin (BCG) vaccine for tuberculosis (TB).

Early identification is required to reduce the growing worldwide healthcare burden of TB. One of the biggest hurdles is to differentiate people infected with TB from those who have received the BCG vaccine. An international research team from Malaysia and Iran, led by Taha Roodbar Shojaei and Mohamad Amran Mohd Salleh of Universiti Putra Malaysia (Selangor, Malaysia), have developed a layered biosensor using modified quantum dots, gold nanoparticles, and single-strand DNAs (two specific oligonucleotides against early secretory antigenic target 6). The sensor not only detects TB in patient sputum but also differentiates positive results from samples of vaccinated people. The sensor requires small amounts of sputum and could therefore be used where limited sample volumes are available.

Using the new sensor, the team has conducted preliminary tests on 50 clinical samples from patients in Tehran who were suspected of having TB. While current PCR-based diagnostic TB tests have an approximately 80% success rate for both sensitivity and specificity, the sensor test (based on this initial sample set) had 94.2% sensitivity and 86.6 % specificity. Its unique advantages in terms of turnaround time, higher sensitivity and specificity, as well as a lower (10-fold) detection limit would recommend this test as a more appropriate and cost-effective tool for large scale operations.

In 2015, the team is working to further enhance the biosensor with carbon nanoparticles instead of gold. They also plan to develop the device and interface to further simplify detection, perhaps with a smartphone app.

The report, by Shojaei TR, et al, was published in the November-December 2014 issue of the Brazilian Journal of Infectious Diseases.

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