A DNA biochip for on-the-spot multiplexed pathogen identification

Yeung, Siu-Wai; Lee, Thomas Ming-Hung; Cai, Hong; Hsing, I-Ming

Decentralized medical testing plays a vital role in today's health care system. The blood glucose meter, which was the first commercial handheld device for medical diagnostics and developed three decades ago, is by far one of the most successful examples in point-of-care testing (POCT). In the years to come, driven by the ever-growing threats from emerging infectious diseases (e.g. avian flu and severe acute respiratory syndrome), the development of small-size instruments for on-the-spot pathogen detection is expected to be an important segment of the POCT market. This trend has already commenced with a few companies having launched self-test products for hepatitis and human immunodeficiency virus detection based on antibody-antigen interactions (e.g. OraSure Technologies and ACON Laboratories). These systems give a visual readout indicating the presence or absence of the target virus in $15 min. One of the main shortcomings of these immunological techniques is their limited sensitivity. To address this issue, there have been significant efforts to develop nucleic acid (NA)-based analyzers (1) (2) (3) . The miniaturization of NA analytical platforms has many advantages over the conventional bench-top counterparts. These include low sample/reagent consumption (volume of micro-down to picoliter) as well as short assay time (minutes rather than days). Most importantly, they permit the integration of a number of functions including sample preparation, target amplification, and product detection, thus enabling a fully automated operation that can be used by untrained individuals.