Flow-through functionalized PDMS microfluidic channels with dextran derivative for ELISAs.

In this work, a dextran modified PDMS microfluidic ELISA device was fabricated. The dextran functionalization was conducted with a simple, economic and fast flow-through process in a fabricated PDMS microfluidic device, and demonstrated significant enhancement of hydrophilicity and efficient covalent immobilization of proteins on the PDMS microchannel surface. The device was used to simultaneously detect multiple important biomarker IL-5, HBsAg, and IgG, showing a limit of detection of 100 pg mL(-1) and a dynamic range of 5 orders of magnitude, which significantly improved the performance of the reported hydrophobic and plasma-treated hydrophilic PDMS flow-through immunoassay devices. The fabricated PDMS device demonstrated its capability for colorimetric detection of proteins through direct observation by human eyes. Thus, this work not only demonstrates great potential to fabricate an economical and sensitive lab-on-chip system for high throughput screening of various infectious diseases, but also provides an opportunity to develop a portable microfluidic ELISA device via human eye examination for heath point-of-care services.