A 48-well microfluidic platform based on immuno-NASBA assay to quantify traces of soluble biomarkers in water environment

Microfluidic devices can automatically perform multiple laboratory functions on a single, compact and integrated chip. This study demonstrates that a new concept lab-on-a-chip system is able to quantify soluble biomarkers in water environment with femtomolar sensitivity, high specificity and ability for middle throughput monitoring. This system is based on a new assay named `real-time immuno-nucleic acid sequence-based amplification´ (immuno-NASBA), which general scheme is similar to a sandwich antibody-mediated immuno-PCR assay. However, the barcode DNA linked with antibodies in the immunoassay contains a T7 RNA polymerase promoter is utilized as the template in the following nucleic acid sequence-based amplification (NASBA) assay. Compared with PCR, NASBA is an isothermal amplification assay which can greatly simplify microfluidic devices with the similar ultra-sensitivity. Thanks to the simplification of NASBA chip, the prototype microfluidic device introduced in this paper contains 48 reaction chambers that can be used to measure the concentrations of multiple biomarkers at the same time. The immuno-NASBA chip provides a novel tool of water environmental protection to monitor water quality in both lakes and rivers, which can also be used to detect water-borne disease or early warning of water environment pollution.