Enhancement of coherent optical signal from tissue phantom by gold nanorods in near-infrared range

To investigate gold nanorods as a contrast agent to enhance signal to noise ratio(SNR) and contrast of spectroscopic optical coherence tomography imaging of the turbid tissue sample, suspensions of silica coated plasmon resonant gold nanorods (GNRs) and biological dye(India ink) were used in gelatin-based phantoms. With the same background scattering condition caused by TiO2 microspheres, samples of single and double layers were fabricated and test. By comparison of the signal to noise ratio and slop of the depth-dependent signal, some different properties appeared between nanoparticle and biological dye. Unlike simple absorption of ink, GNRs have narrow absorption peak and scattering property which will enhance backscattering in the area of aggregation. A 10 dB enhancement of SNR has been observed in double-layer sample. GNRs tend to gather around interface of two layers and generate the photon-thermal effect that also enhance the signal intensity. (C) 2016 Elsevier GmbH. All rights reserved.