A point-of-need enzyme linked aptamer assay for Mycobacterium tuberculosis detection using a smartphone

Due to the poor sensitivities and specificities of antibody based point of need devices, we have developed a low-cost and reliable latent tuberculosis infection (LTBI) screening system based on enzyme linked aptamers which are cost effective and chemically stable. Specific recognition of mannose-capped lipoarabinomannan on the surface of Mycobacterium tuberculosis has been achieved for the development of direct and indirect dot-blot approaches which are designed for simultaneous quantitative analysis of multiple samples and identification of mycobacterial strains, respectively. Compared with traditional acid-fast staining assay used for LTBI screening, our direct dot-blot system has offered a lower limit of quantitation at 10(4) CFU/mL and higher accuracy. In contrast to traditional bacterial culture approach which takes 35 weeks, our assay can be completed within 5 h, which is a remarkable increase in assay efficiency. To maximize the portability and fulfill the needs for LTBI screening in developing countries, an Android application has been developed to carry out colorimetric analysis of images captured by a smartphone camera, followed by generating and sharing of diagnostic reports through internet connectivity. Upon promotion, we believe this low-cost and effective LTBI screening system will control the outspread of tuberculosis and save many lives, particularly in developing countries.