Using Light to Manipulate Small Particles


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Using Light to Manipulate Small Particles  - High Tech Startups

Light may be most well known for its wave-like properties, but it also has a particle nature, with an infinitesimally small but finite mass and velocity. It can move individual cells as small as 10 to 100 microns. But commercially available optical "tweezers" can't move particles that are much smaller, such as bacteria, viruses, proteins, or DNA.

Optofluidics, Inc., a Philadelphia-based life-sciences company, is commercializing a technology that not only detects but also manipulates particles much smaller than cells. This has enormous implications for biological research and pharmaceuticals.

Tractor Beams for Molecules

Optical tweezers use intense lasers that emit photons with enough momentum to push particles that are sufficiently small. But, diffraction of their 400- to 800-nm laser light limits their ability to focus on spots smaller than 1 micron. A laser can't trap a particle that small if it can't focus on it.

To manipulate particles 1,000 times smaller, Optofluidics generates tight optical spots by shooting a laser into a chip that contains waveguides. The chip guides and amplifies the light into a small spot. Microfluidics carries a particle from solution to a region in front of the light, and the light holds it there indefinitely. Turning the light off releases the particle.

Optofluidics's co-CEO Bernardo Cordovez describes this technology, which was born at the Erickson Lab at Cornell University, as a "molecular tractor beam." It's a non-invasive process using light and it doesn't pinch or interfere with the particle. It is free to move around inside the trap in solution and diffuse to its natural state because no chemical bonds or other factors are pinning the particle in a specific location or orientation.

Using Light to Manipulate Small Particles - High Tech Startups

The NanoTweezer system in the final stages of development and testing.
Image source: Optofluidicscorp.com

This free-solution light-trapping technology allows researchers to observe particle mechanics and interactions with other particles in real time, for example how a protein folds or unfolds. It also allows researchers to look at individual molecules, which can provide more detailed information than is gathered from aggregate results typically obtained with surface chemistry.

Part of Optofluidics's commercialization challenge is providing the ability to automate experiments at the nanoscale level. "Automating is difficult, but using a molecular tractor beam replaces tedious surface chemistry techniques that may take weeks with a process that may take only a few hours," says Cordovez, a PhD who was named the Philadelphia Business Journal's "Top 30 under 30" in 2011.

Using the Chip for Sensing

Optofluidics's chip can also sense if a particle is present. It has sufficient sensitivity to detect very dilute amounts of specific proteins in blood. Together with partner Banyan Biomarkers, it is developing a biomolecular sensing tool for protein biomarkers that are present during traumatic brain injuries.

It is also developing "front-end" techniques that integrate with its Nanoscale Optofluidic Sensor Array technology. Ideally, users collect raw blood samples from a fingerprint, and it separates and filters the proteins from the red cells and plasma, and performs detection.

What's Ahead

Optofluidics has demonstrated proof-of-concept of both technologies, and will commercialize them first as scientific instruments rather than diagnostic products given the complex regulatory environment surrounding diagnostics, says Cordovez.

Since starting operations in January 2011 with co-founder David Erickson, who is also a mechanical engineering professor at Cornell University, Cordovez says Optofluidics has three full-time employees and two interns and is in a pre-revenue stage. It was named the Greater Philadelphia Region Life Science Startup of the Year by the Philadelphia Alliance for Capital and Technologies.

Optofluidics has completed a round of $2 million of federal funding through the National Science Foundation and the Defense Army Research Projects Agency, and is in the process of securing private financing to bring these technologies to the market.

Debbie Sniderman is CEO of VI Ventures LLC, a technical consulting company.

Automating is difficult, but using a molecular tractor beam replaces tedious surface chemistry techniques that may take weeks with a process that may take only a few hours.

Bernardo Cordovez, co-CEO, Optofluidics, Inc.

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July 2012

by Debbie Sniderman, ASME.org