Squeezing red blood cells on an optical waveguide to monitor cell deformability during blood storage.

Red blood cells squeeze through micro-capillaries as part of blood circulation in the body. The deformability of red blood cells is thus critical for blood circulation. In this work, we report a method to optically squeeze red blood cells using the evanescent field present on top of a planar waveguide chip.

Raman scattering in pathology.

Raman scattering is the inelastic scattering of light by chemical bonds, and can therefore show molecular specificity. It can be used both in pure spectroscopy mode, and in imaging mode. While many applications of Raman spectroscopy and imaging in the biomedical field have been so far demonstrated, the use of this technology for pathology applications is still in its early stages.

Serial Raman spectroscopy of particles trapped on a waveguide.

We demonstrate that Raman spectroscopy can be used to characterize and identify particles that are trapped and propelled along optical waveguides. To accomplish this, microscopic particles on a waveguide are moved along the waveguide and then individually addressed by a focused laser beam to obtain their characteristic Raman signature within 1 second acquisition time. The spectrum is used to distinguish between glass and polystyrene particles.

Raman scattering in pathology.

Raman scattering is the inelastic scattering of light by chemical bonds, and can therefore show molecular specificity. It can be used both in pure spectroscopy mode, and in imaging mode. While many applications of Raman spectroscopy and imaging in the biomedical field have been so far demonstrated, the use of this technology for pathology applications is still in early stages.

Differential imaging of biological structures with doubly-resonant coherent anti-stokes Raman scattering (CARS).

Coherent Raman imaging techniques have seen a dramatic increase in activity over the past decade due to their promise to enable label-free optical imaging with high molecular specificity. The sensitivity of these techniques, however, is many orders of magnitude weaker than fluorescence, requiring milli-molar molecular concentrations. Here, we describe a technique that can enable the detection of weak or low concentrations of Raman-active molecules by amplifying their signal with that obtained from strong or abundant Raman scatterers.

Tracking and quantitation of fluorescent HIV during cell-to-cell transmission.

The green fluorescent protein (GFP) is a powerful genetic marking tool that has enabled virologists to monitor and track viral proteins during HIV infection. Expression-optimized Gag-GFP constructs have been used to study virus-like particle (VLP) assembly and localization in cell types that are easily transfected. The development of HIV-1 variants carrying GFP within the context of the viral genome has facilitated the study of infection and has been particularly useful in monitoring the transfer of virus between cells following virological synapse formation.

Three-dimensional structured illumination microscopy of liver sinusoidal endothelial cell fenestrations.

Fenestrations are pores in liver sinusoidal endothelial cells that filter substrates and debris between the blood and hepatocytes. Fenestrations have significant roles in aging and the regulation of lipoproteins. However their small size (<200 nm) has prohibited any functional analysis by light microscopy.

Fatty acids from very low-density lipoprotein lipolysis products induce lipid droplet accumulation in human monocytes.

One mechanism by which monocytes become activated postprandially is by exposure to triglyceride-rich lipoproteins such as very low-density lipoproteins (VLDL). VLDL are hydrolyzed by lipoprotein lipase at the blood-endothelial cell interface, releasing free fatty acids. In this study, we examined postprandial monocyte activation in more detail, and found that lipolysis products generated from postprandial VLDL induce the formation of lipid-filled droplets within cultured THP-1 monocytes, characterized by coherent antistokes Raman spectroscopy.

Physico-chemical characterization of polylipid nanoparticles for gene delivery to the liver.

Polylipid nanoparticles (PLNP) have been shown to be very effective in delivering antioxidative genes in the treatment of liver injury in mice. To build on our previous studies and to further characterize PLNP formulated from polycationic lipid (PCL) and cholesterol, we report here the synthesis of multigram quantities of PCL and employ analytical tools, such as Raman spectroscopy of single PLNP and live-cell imaging of lipofection, for the physicochemical characterization of PCL, PLNP, and the transfection process. Mass spectrometry demonstrates the characteristics of polymeric lipids.

Growth, differentiation, and biochemical signatures of rhesus monkey mesenchymal stem cells.

The goal of this study was to compare the growth and differentiation potential of rhesus monkey mesenchymal stem cells (rhMSCs) from different age groups (fetal, newborn, infant, juvenile), and to use confocal micro-Raman spectroscopy to assess the intrinsic biomolecular profiles of individual rhMSCs. Results indicated that fetal cells had significantly shorter population doubling times during the log growth phase (23.3 +/- 1.

Surface-enhanced Raman scattering from individual au nanoparticles and nanoparticle dimer substrates.

Surface-enhanced Raman scattering (SERS) intensities for individual Au nanospheres, nanoshells, and nanosphere and nanoshell dimers coated with nonresonant molecules are measured, where the precise nanoscale geometry of each monomer and dimer is identified through in situ atomic force microscopy. The observed intensities correlate with the integrated quartic local electromagnetic field calculated for each specific nanostructure geometry. In this study, we find that suitably fabricated nanoshells can provide SERS enhancements comparable to nanosphere dimers.