Application of a Novel Murine Ear Vein Model to Evaluate the Effects of a Vascular Radioprotectant on Radiation-Induced Vascular Permeability and Leukocyte Adhesion.

Vascular injury after radiation exposure contributes to multiple types of tissue injury through a cascade of events. Some of the earliest consequences of radiation damage include increased vascular permeability and promotion of inflammation, which is partially manifested by increased leukocyte-endothelial (L/E) interactions. We describe herein a novel intravital imaging method to evaluate L/E interactions, as a function of shear stress, and vascular permeability at multiple time points after local irradiation to the ear.

Tunable and amplified Raman gold nanoprobes for effective tracking (TARGET): in vivo sensing and imaging.

We describe the development of a highly tunable, physiologically stable, and ultra-bright Raman probe, named as TARGET (Tunable and Amplified Raman Gold Nanoprobes for Effective Tracking), for in vitro and in vivo surface-enhanced Raman scattering (SERS) applications. The TARGET structure consists of a gold core inside a larger gold shell with a tunable interstitial gap similar to a "nanorattle" structure. The combination of galvanic replacement and the seed mediated growth method was employed to load Raman reporter molecules and subsequently close the pores to prevent leaking and degradation of reporters under physiologically extreme conditions.

Snap-shot multispectral imaging of vascular dynamics in a mouse window-chamber model.

Understanding tumor vascular dynamics through parameters such as blood flow and oxygenation can yield insight into tumor biology and therapeutic response. Hyperspectral microscopy enables optical detection of hemoglobin saturation or blood velocity by either acquiring multiple images that are spectrally distinct or by rapid acquisition at a single wavelength over time. However, the serial acquisition of spectral images over time prevents the ability to monitor rapid changes in vascular dynamics and cannot monitor concurrent changes in oxygenation and flow rate.

Oxygen Sensing Difluoroboron Dinaphthoylmethane Polylactide.

Dual emissive luminescence properties of solid-state difluoroboron β-diketonate-poly(lactic acid) (BFbdk-PLA) materials have been utilized as biological oxygen sensors. Dyes with red-shifted absorption and emission are important for multiplexing and imaging, thus hydroxyl-functionalized dinaphthoylmethane initiators and dye-PLA conjugates BFdnm(X)PLA (X = H, Br, I) with extended conjugation were synthesized. The luminescent materials show red-shifted absorbance (~435 nm) and fluorescence tunability by molecular weight.

Luminescent difluoroboron β-diketonate PEG-PLA oxygen nanosensors for tumor imaging.

Surface modification of nanoparticles and biosensors is a dynamic, expanding area of research for targeted delivery in vivo. For more efficient delivery, surfaces are PEGylated to impart stealth properties, long circulation, and enable enhanced permeability and retention (EPR) in tumor tissues. Previously, BF2 dbm(I)PLA was proven to be a good oxygen nanosensor material for tumor hypoxia imaging in vivo, though particles were applied directly to the tumor and surrounding region.

Restoration of intracellular ATP production in banked red blood cells improves inducible ATP export and suppresses RBC-endothelial adhesion.

Transfusion of banked red blood cells (RBCs) has been associated with poor cardiovascular outcomes. Storage-induced alterations in RBC glycolytic flux, attenuated ATP export, and microvascular adhesion of transfused RBCs in vivo could contribute, but the underlying mechanisms have not been tested. We tested the novel hypothesis that improving deoxygenation-induced metabolic flux and the associated intracellular ATP generation in stored RBCs (sRBCs) results in an increased extracellular ATP export and suppresses microvascular adhesion of RBCs to endothelium in vivo following transfusion.

Automated non-rigid registration and mosaicing for robust imaging of distinct retinal capillary beds using speckle variance optical coherence tomography.

Variance processing methods in Fourier domain optical coherence tomography (FD-OCT) have enabled depth-resolved visualization of the capillary beds in the retina due to the development of imaging systems capable of acquiring A-scan data in the 100 kHz regime. However, acquisition of volumetric variance data sets still requires several seconds of acquisition time, even with high speed systems. Movement of the subject during this time span is sufficient to corrupt visualization of the vasculature.

Depth-Encoded Spectral Domain Phase Microscopy for Simultaneous Multi-Site Nanoscale Optical Measurements.

Spectral domain phase microscopy (SDPM) is an extension of spectral domain optical coherence tomography (SDOCT) that exploits the extraordinary phase stability of spectrometer-based systems with common-path geometry to resolve sub-wavelength displacements within a sample volume. This technique has been implemented for high resolution axial displacement and velocity measurements in biological samples, but since axial displacement information is acquired serially along the lateral dimension, it has been unable to measure fast temporal dynamics in extended samples. Depth-Encoded SDPM (DESDPM) uses multiple sample arms with unevenly spaced common path reference reflectors to multiplex independent SDPM signals from separate lateral positions on a sample simultaneously using a single interferometer, thereby reducing the time required to detect unique optical events to the integration period of the detector.

Doppler velocity detection limitations in spectrometer-based versus swept-source optical coherence tomography.

Recent advances in Doppler techniques have enabled high sensitivity imaging of biological flow to measure blood velocities and vascular perfusion. Here we compare spectrometer-based and wavelength-swept Doppler OCT implementations theoretically and experimentally, characterizing the lower and upper observable velocity limits in each configuration. We specifically characterize the washout limit for Doppler OCT, the velocity at which signal degradation results in loss of flow information, which is valid for both quantitative and qualitative flow imaging techniques.

Synthetic wavelength based phase unwrapping in spectral domain optical coherence tomography.

Phase sensing implementations of spectral domain optical coherence tomography (SDOCT) have demonstrated the ability to measure nanometer-scale temporal and spatial profiles of samples. However, the phase information suffers from a 2pi ambiguity that limits observations of larger sample displacements to lengths less than half the source center wavelength. We introduce a synthetic wavelength phase unwrapping technique in SDOCT that uses spectral windowing and corrects the 2pi ambiguity, providing accurate measurements of sample motion with information gained from standard SDOCT processing.

Combined hyperspectral and spectral domain optical coherence tomography microscope for noninvasive hemodynamic imaging.

We have combined hyperspectral imaging with spectral domain optical coherence tomography (SDOCT) to noninvasively image changes in hemoglobin saturation, blood flow, microvessel morphology, and sheer rate on the vessel wall with tumor growth. Changes in these hemodynamic variables were measured over 24 h in dorsal skin fold window chamber tumors. There was a strong correlation between volumetric flow and hemoglobin saturation (rho=0.