Virginia Tech researchers have created a highly efficient microfluidic chromatin immunoprecipitation (ChIP) device for extracting ChIP DNA. High efficiency extraction of ChIP DNA from cells often represents a critical roadblock for increasing the sensitivity of ChIP assays.
This new microfluidic device takes advantage of the improvement in precipitation efficiency in a microscale chamber to reduce the duration of immunoprecipitation from overnight (in conventional protocols) to less than 100 min. After optimizing the bead coating and bead amount, the inventors were able to extract >1 ng ChIP DNA from as few as 10000 cells and this yield was roughly ~100 fold higher than the previous reports (10~50 pg from 10000 cells).
This microfluidic ChIP technology is superior for immunoprecipitation for several reasons. First, microfluidic chambers offer tiny volumes that build up high concentrations from trace amounts of molecules. Such high concentrations facilitate adsorption kinetics and completeness. Second, in this design, IP beads are used that take up a substantial fraction of the tiny volume (e.g. 15-40%, compared to 5% in the standard ChIP28) so that the surface area/volume ratio is huge. The increased contact between the bead surface (coated with antibody) and the target protein-DNA complexes promotes high efficiency for ChIP. Third, a unique feature of this device is that it has structures and setup for oscillatory washing of beads. Alternating pressure pulses were applied at the two ends of the microfluidic chamber to move the beads back and forth. Such arrangement effectively removes nonspecific adsorption after high efficiency adsorption. Finally, microfluidics also offers the additional benefits of integrating various steps and minimizing material loss among these steps.
Virginia Tech Intellectual Properties is seeking a commercialization partner to bring this innovative new device to market.