The device uses a fluid flow to drive particulate samples through a network of flowing channels. Laser light is then introduced to interact with the particles and reveal optical force by way of radiation pressure.
“This force, when balanced against the fluidic ‘drag’ on the particles, results in changes to the particle’s velocity,” said Dr. Greg Collins, head, Chemical Dynamics and Diagnostics Branch. “This can be used to identify differing particles or changes within populations of particles based on intrinsic differences in cell biochemistry, morphology and deformability.”
According to Collins, laser separation is achieved when particles transported by laminar flow within a micron-sized channel encounter a highly-focused laser beam directed in the opposite direction. These particles are exposed to optical pressure near the beam focal point, i.e., the region of highest photon density, which is intense enough to impart momentum sufficient to overcome the fluid drag force. The result is that particles become trapped, or have their velocities altered, within the fluid flow until the beam diverges and the photon density decreases.
“Using this laser technique, scientists are able to exploit the inherent differences in optical pressure, which arise from variations in particle size, shape, refractive index, or morphology as a means of separating and characterizing particles,” said Collins. “When samples are optically retained within the system, squeezed between the fluid flow and the retaining laser force, the extent to which they are retained, deformed, or ‘squished,’ by the force of the laser and the fluid flow is related to their composition and biomechanical structure.”
Biological cells are affected by diseases, such as cancer, with potential changes in the fibrous proteins (cytoskeleton) that govern the shape and movement of a biological cell. Red blood cells (erythrocytes) undergo age-dependent stretching and compression, with older erythrocytes being less flexible. The potential for analysis of disease states in biological systems, including cells and small tissue samples, is substantial and wide-ranging.
Under license #NRL-LIC-13-5-284, LumaCyte, LLC has commercialized the technology to launch their revolutionary apparatus RadianceTM t that allows users to identify new or changed cell phenotypes in the absence of antibody based labeling – a costly, time consuming process that requires prior sample knowledge and may activate cells, which can lead to erroneous conclusions.
Radiance can, for example, detect and measure viral infection of mammalian cells quickly and effectively for diagnostic purposes and vaccine manufacturing, making this LumaCyte’s initial target market. The gold standard viral plaque assay and component based methods generally take between 5 -15 day. Radiance can typically accomplish this measurement in 1-2 days or less with high quality data and reduced variability, while simultaneously reducing labor and cost. The technology is not limited to virology, and can be applied in many R&D areas including cancer, induced pluripotent stem cells, cell clearance, and drug development.
Issued March 14, 2017, by the United States Patent and Trademark Office (USTPO), patent #9594071-B2 names Dr. Sean J. Hart, Dr. Colin G. Hebert and Mr. Alex Terray of NRL’s Chemistry Division as inventors and co-contributors.
LumaCyte is an advanced research and instrument development company headquartered in Charlottesville, Virginia. It produces revolutionary cell analysis and sorting instrumentation that does not require the use of antibody or genetic labelling for the analysis of cells. The revolutionary technology uses optical and fluidic forces within a microfluidic device to identify and measure intrinsic properties of single cells. Applications of LumaCyte’s label-free platform technology include viral infectivity for vaccine manufacturing, cancer biology, infectious disease, and pre-clinical drug discovery.