Magnetic Beads Separation
Microchip Biotechnologies is advancing its microfluidic program into the prototype phase. In this phase, the company is focusing on sample preparation as the most commercially viable component of its early development program. “There’s an urgent need for universal sample preparation,” pointed out Joanne Horn, Ph.D., senior staff scientist.
“The BeadStorm™ platform uses magnetic beads to purify cellular targets from such complex matrices as blood or aerosols. The process is straightforward,” she added. The purified target sample is lysed mechanically with technology that emerged from work at the Keck Graduate Institute of Applied Life Sciences.
“Then, released DNA is captured on a second set of magnetic beads, and the concentrated sample is magnetically separated and then washed.” The advantage of magnetic beads, Dr. Horn pointed out, is that they purify and concentrate the target in one step, leaving the output as DNA that has been selectively separated, concentrated, and purified for specific targets.
The platform is engineered to interface with several different downstream analytic platforms, according to Dr. Horn, and possibly with an upstream raw sample collector such as an aerosol sampler. To do so, a modular design is vital.
“The heart of the BeadStorm system is the plastic cube, a 1 inch (2.5 cm) disposable processing device that processes samples using an interfaced, bonded microfluidic chip,” she added.
The system has been used successfully in forensics work involving DNA extraction and purification from buccal swabs, and is being expanded to include an upstream immunomagnetic separation in the workflow. “That process was optimized in previous work.”
The sample-prep technology could be used in the field to monitor military field operations and personnel, as well as testing air, water, and food.
The technology can process four multiplexed samples in about 25 minutes. Microchip Biotechnologies plans to expand that to eight samples. The benefits of this platform include simplified operation and increased accuracy through automation, use of fewer reagents, and multiplexing, according to the company.
IQuum is using its Liat™ system, based upon its lab-in-a-tube technology, to develop a field-deployable identification and confirmation system that is fast, accurate and inexpensive. This integrated system is fully automated, from accepting raw sample through real-time PCR and agent identification. As such, is it designed for first responders who may lack specialized training.
The system includes the disposable, flexible, Liat Tube, with prepackaged reagents, a stand-alone analyzer, an integrated sample processor with an embedded computer for network connectivity, and automation control and readout display.
Assays are performed by actuators that compress the tube to selectively release reagents, move the sample from one segment of the tube to another, and control reaction condition by adding magnetic beads or other substances. A 50 microliter rapid PCR can perform 30 samples in about seven minutes. The complete test for an infectious agent, from sample to results, takes about an hour, the company reports.
Also at the biodefense meeting, Samsung Advanced Institute of Technology (SAIT) discussed its fully integrated, pathogen specific DNA extraction device.
The tool is capable of extracting cDNA from whole blood on a CD, using centrifugal microfluidics on the CD platform itself, lysing samples via laser irradiation, separating particles with target-specific antibodies conjugated to magnetic beads, and moving those samples using Ferrowax microvalves.
The entire process, from plasma separation through DNA extraction was completed within 12 minutes and, except for manually loading 100 microliters of whole blood, was completely automated, the firm asserts.
The study extracted hepatitis B and E. coli, with results comparable to those acquired using usual benchtop methods, according to SAIT.