MIT sorts cells with beams of light

December 10, 2007

CAMBRIDGE, Mass. -- Separating out particular kinds of cells from a sample could become faster, cheaper and easier thanks to a new system developed by MIT researchers that involves levitating the cells with light.

The system, which can sort up to 10,000 cells on a conventional glass microscope slide, could enable a variety of biological research projects that might not have been feasible before, its inventors say. It could also find applications in clinical testing and diagnosis, genetic screening and cloning research, all of which require the selection of cells with particular characteristics for further testing.

Joel Voldman, an associate professor in MIT's Department of Electrical Engineering and Computer Science, and Joseph Kovac, a student in the department, developed the new system, which is featured as the cover story in the Dec. 15 issue of the journal Analytical Chemistry.

Present methods allow cells to be sorted based on whether or not they emit fluorescent light when mixed with a marker that responds to a particular protein or other compound. The new system allows more precise sorting, separating out cells based not just on the overall average fluorescent response of the whole cell but on responses that occur in specific parts of the cell, such as the nucleus. The system can also pick up responses that vary in how fast they begin or how long they last.

"We've been interested in looking at things inside the cell that either change over time, or are in specific places," Voldman says. Separating out cells with such characteristics "can't be done with traditional cell sorting."

For example, if cells differ in how quickly they respond to a particular compound used in the fluorescent labeling, the new system would make it possible to "select out the ones that are faster or slower, and see what's different," says Voldman, who also has appointments in MIT's Research Laboratory of Electronics and the Microsystems Technology Laboratories.

"It seems like that should be easy, but it isn't," he said. There are other ways of accomplishing the same kind of cell separation, but they require complex and expensive equipment, or are limited in the number of cells they can process.

The new system uses a simple transparent silicone layer bonded to a conventional glass microscope slide. Fabricated in the layer are a series of tiny cavities, or traps, in which cells settle out after being added to the slide in a solution. Up to 10,000 cells could be sorted on a single slide.

Looking through the microscope, either a technician or a computerized system can check each cell to determine whether it has fluorescence in the right area or at the right time to meet the selection criteria. If so, its position is noted by the computer. At the end of the selection process, all of the cells whose positions were recorded are then levitated out of their traps using the pressure of a beam of targeted light from a low-cost laser. A flowing fluid then sweeps the selected cells off to a separate reservoir.

The laser levitation of the cells acts like "a fire hose pushing up a beach ball," Voldman says. But the laser method is gentle enough that the living cells remain viable after the process is complete, allowing further biological testing.

Voldman and Kovac are continuing to refine the system, working on making it easier to use and on improving its ability to keep samples sterile. Voldman says that unlike expensive separation techniques such as optical tweezers, the new system could cost only a few thousand dollars. As a result, it could be employed in a variety of biological research laboratories or clinical settings, not just in big, centralized testing facilities.
-end-
The research was funded by the National Institutes of Health and the Singapore-MIT Alliance; Kovac is supported by an ASEE National Defense Science and Engineering Graduate Fellowship.

Written by David Chandler, MIT News Office

Massachusetts Institute of Technology

Related Microscope Articles from Brightsurf:

Microscope lens inspired by lighthouse
Custom-fabricated lenses make it easy to attach high-tech microscopes directly to cell incubators.

Print your own laboratory-grade microscope for US$18
For the first time, labs around the world can 3D print their own precision microscopes, thanks to an open-source design created at Bath.

Novel high-speed microscope captures brain neuroactivities
A research team led by Dr. Kevin Tsia from the University of Hong Kong (HKU); and Professor Ji Na, from the University of California, Berkeley (UC Berkeley) has successfully recorded the millisecond electrical signals in the neurons of an alert mouse with their super high-speed microscope - two-photon fluorescence microscope.

Graphene forms under microscope's eye
Scientists record the formation of foamy laser-induced graphene made with a small laser mounted to a scanning electron microscope.

Hybrid microscope could bring digital biopsy to the clinic
By adding infrared capability to the ubiquitous, standard optical microscope, researchers at the University of Illinois at Urbana-Champaign hope to bring cancer diagnosis into the digital era.

An ultrafast microscope for the quantum world
Processes taking place inside tiny electronic components or in molecules can now be filmed at a resolution of a few hundred attoseconds and down to the individual atom.

SLAP microscope smashes speed records
A new 2-photon microscope captures videos of the brain faster than ever, revealing voltage changes and neurotransmitter release.

New 3D microscope visualises fast biological processes better than ever
Researchers from the European Molecular Biology Laboratory (EMBL) in Heidelberg have combined their expertise to develop a new type of microscope.

Use a microscope as a shovel? UConn researchers dig it
Using a familiar tool in a way it was never intended to be used opens up a whole new method to explore materials, report UConn researchers.

New method gives microscope a boost in resolution
Scientists at the University of W├╝rzburg have been able to boost current super-resolution microscopy by a novel tweak.

Read More: Microscope News and Microscope Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.