George Whitesides at Harvard truly transformed the field of microfluidics by making it accessible to a standard research laboratory. His PDMS (Polydimethyl siloxane) based technology allowed microfluidics channels as small as 10-20 um to be fabricated reproducible and in large numbers for use in making small devices. Biochips have benefited tremendously from this technology and over years several innovative designs have been proposed for multiplexed detection. The power of microfluidics was on full display during recent Oakridge Conference on Frontiers in Clinical Diagnostics(Baltimore, MD April 16-17) where several companies presented their POC (Point of Care) devices that MAY possibly change your experience during your next doctors visit. These POC will allow doctors or individual themselves to test for several common clinical markers. I said ‘MAY’ because journey for a prototype to make it to real clinical testing is long one. It is tough very tough.
And so I got excited when came across a paper in Nature Biotech on “Integrated Barcode Biochips–“(26(12) p:1373;2008) by James Heath. Now using microfluidics for biochips is nothing new, the cool factor in this paper is the combination of two technologies-online separation of plasma from the blood, and DNA based patterning of antibodies.
Picture from physorg.com
A drop of blood when added to the biochip separated plasma from cells and routed to individual channels where multiple analytes are detected using specific antibodies. Final detection is done using sandwich based assay and biochip is read using microarray fluorescent scanner. In the current format detection is done in three steps-blood sample, biotin labeled detection antibody and finally streptavidin labeled with fluor. According to authors, online separation will allow quick analysis and may enable detection of short lived protein population is the blood, though no such example is given.
Technology is good but what are the chances of it making it to clinic! My disclaimer – any technology if given enough time and resources can be commercialized. Saying this there are several similar technology in commercialization pipeline. Two that come to mind are Claros Diagnostics and 4Castchip from Amic now part of Johnson and Johnson. Several other initiatives use innovation in fluid movement and multiplexed immunoassay to develop POC devices. All these devices need extensive validation to be successful.