Biology subjects

Winetraub, Y.

Publications and source records attributed to Winetraub, Y..

3 recordsLinked to original sources

bioRxiv2018

Real-time detection of circulating tumor cells in living animals using functionalized large gold nanorods

Optical coherence tomography (OCT) with significant speckle reduction can be used with highly-scattering contrast agents for noninvasive, contrast-enhanced imaging of living tissue at the cellular scale. The advantages of reduced speckle noise and improved targeted contrast can be harnessed to track objects as small as 2 m in vivo, with the potential for cell tracking and counting in living subjects. Here we demonstrate the use of Large Gold Nanorods (LGNRs) as contrast agents for detecting individual micron-sized polystyrene beads and single myeloma cells in blood circulation using speckle modulating-OCT (SM-OCT). This is the first time that OCT has been used to image at the individual cell scale in vivo. This technical capability presents an exciting opportunity for the dynamic detection and quantification of tumor cells circulating in living subjects.

bioengineering↗

bioRxiv2018

Gold Nanoprisms as Optical Coherence Tomography Contrast Agents in the Second Near Infrared Window for Enhanced Angiography in Live Animals

Optical coherence tomography angiography (OCTA) is an important tool for investigating vascular networks and microcirculation in living tissue. Traditional OCTA detects blood vessels via intravascular dynamic scattering signals derived from the movements of red blood cells (RBCs). However, the low hematocrit and long latency between RBCs in capillaries makes these OCTA signals discontinuous, leading to incomplete mapping of the vascular networks. OCTA imaging of microvascular circulation is particularly challenging in tumors due to the abnormally slow blood flow in angiogenic tumor vessels and strong attenuation of light by tumor tissue. Here we demonstrate in vivo that gold nanoprisms (GNPRs) can be used as OCT contrast agents working in the second near infrared window, significantly enhancing the dynamic scattering signals in microvessels and improving the sensitivity of OCTA in skin tissue and melanoma tumors in live mice. This is the first demonstration that nanoparticle-based OCT contrast agent work in vivo in the second near infrared window, which allows deeper imaging depth by OCT. With GNPRs as contrast agents, the post-injection OCT angiograms showed 41% and 59% more microvasculature than pre-injection angiograms in healthy mouse skin and melanoma tumors, respectively. By enabling better characterization of microvascular circulation in vivo, GNPR-enhanced OCTA could lead to better understanding of vascular functions during pathological conditions, more accurate measurements of therapeutic response, and improved patient prognoses.

bioengineering↗

bioRxiv2017

Upper Limit for Angular Compounding Speckle Reduction

Previous studies of angular compounding for speckle reduction in optical coherence tomography may not have fully accounted for optical aberrations, which produce unintended spatial averaging and concomitant loss of spatial resolution. We accounted for such aberrations by aligning our system and measuring distortions in the images, and found that speckle reduction by angular compounding was limited. Our theoretical analysis using Monte Carlo simulations indicates that \"pure\" angular compounding over 13{degrees} (our full numerical aperture) can improve the signal-to-noise ratio by no more than a factor of 1.5, significantly lower than values reported in literature. Analysis suggests that illuminating only part of the lens to further reduce speckle also involves a trade-off with resolution roughly equivalent to spatial averaging. We conclude that angular compounding provides substantially less benefit than previously expected.

bioengineering↗