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

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

To date, several integrated NA-based analytical systems have been commercialized [http://www.cepheid.com/Sites/ cepheid/content.cfm?id¼158 (GeneXpert from Cepheid), http://www.gen-probe.com/prod_serv/inst_dts.asp (Direct Tube Sampling Systems from Gen-Probe), http://www. idahotech.com/razor/index.html (RAZOR from Idaho Technology) and http://www.iquum.com/products/analyzer. shtml (Liat Analyzer from IQuum)]. Despite their wide use in clinical/central laboratories, their application for on-site pathogen monitoring on a routine basis is still limited due to the large footprint and high instrument cost (mainly the complex optics). A promising alternative would be the inherently simple and lost-cost electrochemical method. Over the past decade, despite a great deal of work having been carried out on electrochemical sequence-specific NA sensing (4) (5) (6) , little work has been undertaken on the integration of these with upstream functionalities. In 2004, Liu et al. (7) successfully demonstrated a fully integrated biochip for cell isolation and lysis, target amplification, as well as electrochemical amplicon detection. One relevant feature of their approach is the incorporation of on-chip mixers, valves, and pumps in a self-contained device. However, the design and fabrication of the chip involves many complicated steps, which limits its practical application.