Microbead Capture

Microbead capture technology is the bridge between full scale, real world samples and nanoscale fluidic processes on microchips. The use of coated paramagnetic beads to capture specific biological materials from a variety of matrices is well established and can also offer exquisite discrimination. These microbeads bind and capture target biomolecules from large dilute volumes and concentrate these into microliter or even nanoliter bead bed volumes. Bead capture provides specificity, purification, and volume reduction—key elements in bringing samples onto microfluidics.

BeadStorm

MBI’s BeadStorm™ is a front-end module that captures, purifies, and concentrates milliliter-scale samples to the microfluidic scale using magnetic capture technology. By using magnetic beads with particular affinity reagents and coatings tailored to specific applications, the analyte can be isolated and even amplified downstream in the case of DNA.

In addition to isolating, concentrating, and purifying the analyte, the beads can be introduced into a fluidic format and moved into a MOV™ microchip for on-chip reactions. Using a low pressure gas source, the BeadStorm device moves suspensions of beads through a series of capillary tubes and chambers. The beads can be moved to a heated reaction chamber, pulled into a capture chamber, and/or processed through a clean-up channel. This represents a refined method to manipulate biological material and to move samples.

BeadStorm integrates upstream preparation of difficult samples with volumes up to 10 mL with downstream microanalysis. Multiple sample preparation steps are performed at the microliter scale with complete automation, and detection of minute quantities of the sample is possible. BeadStorm technology has been demonstrated for DNA extraction from buccal swabs and blood samples and has been integrated with fluorescent detection systems.

Microbead Cleanup

Magnetic beads are also used on-chip to perform cleanups, such as sample preparation for DNA sequencing. After template and pre-mix solutions are pumped into reaction chambers and thermocycled, magnetic beads and ethanol are added by robot to the reaction products. Beads are pumped and captured by magnets into MOV features where they are rinsed with wash solutions. For example, this approach can be used to remove excess, unincorporated dye from cycle sequencing reactions that would otherwise interfere with downstream CE-based detection. On MBI’s Apollo 100 DNA is eluted and transferred to microtiter plates—ready for injection onto commercial capillary array systems for analysis.