Photothermal optical coherence tomography based on the localized surface plasmon resonance of Au nanoring

Abstract

The conventional optical coherence tomography (OCT) images based on enhanced scattering and the photothermal (PT) images based on enhanced absorption of the localized surface plasmon (LSP) resonance of Au nanorings (NRIs) in a bio-tissue sample are demonstrated with the scans of an OCT system (1310-nm system), in which the spectral range covers the LSP resonance peak wavelength, and another OCT system (1060-nm system), in which the spectral range is away from the LSP resonance peak wavelength. A PT image is formed by evaluating the modulation frequency (400 Hz) response of an excitation laser with its wavelength (1308 nm) close to the LSP resonance peak at 1305 nm of the Au NRI solution. With the scan of the 1310-nm OCT system, the Au NRI distribution in the bio-tissue sample can be observed in both conventional OCT and PT images. However, with the scan of the 1060-nm OCT system, the Au NRI distribution can be clearly observed only in the PT image. The diffusion process of Au NRIs in the bio-tissue sample can be traced with the scan of either OCT system. Based on phantom experiments, it is shown that the PT image can help in resolving the ambiguity of a conventional OCT image between the enhanced scattering of Au NRIs and the strong scattering of a tissue structure in the 1310-nm OCT scanning. Also, under the condition of weak intrinsic sample scattering, particularly in the scan of the 1060-nm system, the PT signal can be lower than a saturating level, which is determined by the excitation power. By increasing OCT system signal-to-noise ratio or M-mode scan time, the PT signal level can be enhanced.

Detection of plasmonic nanoparticles with full field-OCT: optical and photothermal detection

“…We must mention that OCT has already been used for detection of gold nanoparticles using OCT or dark field OCM [14][15][16][17][18][19]. A modulated heating beam, at the plasmon resonance, creates a locally modulated temperature field and thus a modulated refractive index one.…”

“…Moreover, in all the OCT experiments [14][15][16][17][18][19] described so far, the heating and the probe beams are set in a confocal geometry. This has the advantage of maximizing the power density in the heated volume; nevertheless, the spread of the heating beam due to scattering is noticeable after a few hundred micrometers.…”

“…The spectral region between 650 and 900 nm, called therapeutic window, shows low absorption of hemoglobin (<650 nm) and water (>900 nm). Based on their unique optical and plasmonic properties, gold nanoshells were used as contrast agent for optical imaging such as photoacoustic imaging (PAI), photoacoustic tomography (PAT) [7,8], optical coherence tomography (OCT) [9][10][11][12][13] and photothermal OCT [14][15][16][17][18][19].…”

Characterizing physical properties and in vivo OCT imaging study of Cu-Sn-S nanocrystals

“…The advantages of LSPR make Cu-Sn-S nanocrystals can serve as a contrast-enhanced molecular imaging for cancer detection in clinical setting. Such as Optical Coherence Tomography (OCT), [28][29][30][31][32] magnetic resonance imaging (MRI) and positron emission tomography (PET). As we know, there are many researches have reported the synthesis and characterization of Cu-Sn-S nanocrystals.…”

In vivo photothermal optical coherence tomography for non-invasive imaging of endogenous absorption agents

“…Optical coherence tomography (OCT) enables non-invasive in vivo biopsy of biological samples [1] by imaging the micro-scale inner structure of tissue. In addition to obtaining structural information from the backscattering intensity, the measurement of optical absorption has been attempted; i.e., spectroscopic [2,3], pumpprobe [4], and photothermal OCT [5][6][7][8][9]. Spectroscopic OCT classifies tissue according to the spectrum attenuation, which is the combination of absorption and scattering [2].…”