The challenge, McDevitt said, was defining a new concept to quickly and efficiently capture and detect biomarkers within a microfluidic circuit. The solution developed at Rice is a network of microsponges with tailored pore sizes and nano-nets of agarose fibers. The sponge-like quality allows a lot of fluid to be processed quickly, while the nano-net provides a huge surface area that can be used to generate optical signals 1,000 times greater than conventional refrigerator-sized devices. The mini-sensor ensembles, he said, pack maximum punch.
The team found that agarose beads with a diameter of about 280 micrometers are ideal for real-world applications and can be mass-produced in a cost-effective way. These agarose beads retain their efficiency at capturing biomarkers, are easy to handle and don't require specialized optics to see.
McDevitt and his colleagues tested beads with pores up to 620 nanometers and down to 45 nanometers wide. (A sheet of paper is about 100,000 nanometers thick.) Pores near 140 nanometers proved best at letting proteins infuse the beads' internal nano-nets quickly, a characteristic that enables PBNCs to test for disease in less than 15 minutes.
The team reported on experiments using two biomarkers, carcinoembryonic antigens and Interleukin-1 beta proteins (and matching antibodies for both), purchased by the lab. After soaking the beads in the antibody solutions, the researchers tested their ability to recognize and capture their matching biomarkers. In the best cases, they showed near-total efficiency (99.5 percent) in the detection of bead-bound biomarkers.
McDevitt has expected for some time that a three-dimensional bead had greater potential to capture and hold biomarkers than the standard for such tests, the enzyme-linked immunosorbent assay (ELISA) technique. ELISA analyses flui
|Contact: David Ruth|