Depth resolved photothermal OCT detection of macrophages in tissue using nanorose

Abstract

Application of photothermal Optical Coherence Tomography (OCT) to detect macrophages in ex vivo rabbit arteries which have engulfed nanoclusters of gold coated iron oxide (nanorose) is reported. Nanorose engulfed by macrophages associated with atherosclerotic lesions in rabbit arteries absorb incident laser (800nm) energy and cause optical pathlength (OP) variation which is measured using photothermal OCT. OP variation in polydimethyl siloxane tissue phantoms containing varying concentrations of nanorose match values predicted from nanoparticle and material properties. Measurement of OP variation in rabbit arteries in response to laser excitation provides an estimate of nanorose concentration in atherosclerotic lesions of 2.5x109 particles/ml. OP variation in atherosclerotic lesions containing macrophages taking up nanorose has a different magnitude and profile from that observed in control thoracic aorta without macrophages and is consistent with macrophage presence as identified with RAM-11 histology staining. Our results suggest that tissue regions with macrophages taking up nanorose can be detected using photothermal OCT.

Fast three-dimensional imaging of gold nanoparticles in living cells with photothermal optical lock-in Optical Coherence Microscopy

“…Typical integration times are at least one order of magnitude slower than poli-OCM [20]. Moreover, none of these methods have shown single particle detection [19,21,22].…”

“…The fast volumetric imaging of OCM and the high sensitivity to extrinsic labels of photothermal imaging call for a combination of these two approaches to complement the intrinsic contrast measured by OCM with a specific signal of the photothermal label. Several groups have already explored photothermal signals using OCT [19][20][21][22]. However, in order to obtain an exploitable contrast from AuNPs, all the proposed solutions compromised the speed advantage of OCT: the photothermal signal was extracted from the Fourier transform of the phase signal recorded over time, which required the acquisition of multiple axial profiles at the same lateral position.…”

Magnetomotive Optical Coherence Tomography for the Assessment of Atherosclerotic Lesions Using αvβ3 Integrin-Targeted Microspheres

“…Other research groups have demonstrated that externally injected particles can be taken up by macrophages in atherosclerotic plaques and can be detected by OCT [25, 26], however, in this study, we demonstrate contrast agents for OCT in cardiology that can target the specific biomarkers (e.g., α v β 3 integrin) overexpressed in atherosclerotic lesions. This is especially needed to enhance the early detection and localization of atherosclerotic lesions which may not be clearly evident in structural OCT imaging or in other imaging modalities.…”

Dual-wavelength photothermal optical coherence tomography for imaging microvasculature blood oxygen saturation

“…34 Skala has developed photothermal OCT for high-resolution molecular imaging, 35 and Paranjape has reported using photothermal OCT to detect macrophages in tissue. 36 So far, reported applications of photothermal OCT have focused primarily on light absorption by nanoparticles. Previously, we reported using dual-wavelength photothermal OCT (DWP-OCT) to measure microvasculature SO 2 in both phantom 37 and in vivo 38 blood vessels using a common-path phase-sensitive (PhS) OCT system.…”