Specific adhesion of micron-sized colloids to surfaces mediated by hybridizing DNA chains

摘要

The hybridization of complementary DNA chains can be used to identify unknown strands. Substantial work has been done to link nanoparticles in solution or on surfaces via DNA hybridization. However, few studies have been done on micron-sized particles that can be visually identified using optical microscopy. In this paper, we used 9.95 mum oligonucleotide coated polystyrene microspheres as probes to identify complementary oligonucleotide sequences immobilized on polystyrene substrate surfaces. We showed that particle adhesion is specific and only seen when beads and surfaces are complementary; nonspecific binding was negligible. Using a flow chamber, we studied the effects of shear rate on microsphere detachment as a function of oligonucleotide site density on the substrate. We show that the critical shear rate at which the beads are detached is an increasing function of oligonucleotide substrate site density. Analysis of the microspheres detached from the slide by flow cytometry demonstrated that the bonds cohesively fail due to the physical desorption of the Neutravidin linkages to the polystyrene slide and not due to the breaking of DNA-DNA bonds. With optimization, the attachment and detachment of micron-sized DNA coated particles on arrays hold promise for the specific, selective identification of DNA sequences. [References: 38]