Differential contrast of gold nanorods in dual-band OCT using spectral multiplexing
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In optical coherence tomography (OCT), differential contrast can be generated by resonant nanoparticles using spectral multiplexing. Differential contrast can be of interest for medical applications for improving detection specificity of structures with low endogenous contrast. Differential contrast has been shown using OCT systems with one bandwidth; however, this requires post-processing that is time consuming and reduces image resolution. In this study, we used a dual-band OCT prototype system with two far separated bandwidths in the clinically relevant optical window, and in search for the optimal differential contrast-generating particles for this prototype system, three different gold nanorods (AuNR) samples were investigated. The samples with different particle volume, aspect ratio, and absorption-maximum were imaged in a highly scattering phantom and on chicken muscle. In vitro, differential contrast was observed for the nanorods large (NRL) sample having the absorption-maximum within one bandwidth of the OCT and an average length of 75 nm. For the smaller AuNR (48 nm length) with comparable absorption-maximum, the obtained signal intensities were too low for being visible, although differences in signal intensities between both bandwidths could be measured. NRL optimal concentration for differential contrast using this prototype system is between 100 and 500 µg Au/mL (0.51–2.54 mM). These results demonstrate the potential of real-time imaging of differential contrast in dual-band OCT and motivate in vivo application of plasmon resonant AuNR in order to improve the detection sensitivity for structures that are difficult to identify by OCT such as small blood vessels.
KeywordsDifferential contrast Spectral multiplexing Dual-band optical coherence tomography In vivo measurements Biotissue Small blood vessels
Optical coherence tomography
This research was supported by the German center for interdisciplinary clinical research IZKF and by the “NRW Ziel 2 EFRE (ForSaTum)”. AB and US acknowledge sponsorship by Ziel2.NRW “Regionale Wettbewerbsfähigkeit und Beschäftigung” 2007–2013 co-financed by the European Regional Development Fund (ERDF), Grant no. 005-0908-0117. TW acknowledges financial support provided by the German Research Foundation within the Collaborative Research Center SFB Transregio 37 “Micro- and Nanosystems in Medicine—Reconstruction of Biological Functions”.
Conflict of interest
There is no conflict of interest to be stated.
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