Experimental assessment of gold nanorods for optoacoustic imaging in a tissue-mimicking phantom

Plasmon-resonant gold nanorods (AuNRs) are of great interest for optoacoustic imaging, due to their capacity of generating ultrasound (US) signals when irradiated by Near Infrared light. In fact, detection of emitted acoustic waves could lead to micron-scale resolution imaging and early diagnosis of tumor masses. Nonetheless, until now, no relevant studies have assessed the optoacoustic behavior of AuNRs under repeatable experimental conditions. A new experimental set-up including a novel custom-designed tissue-mimicking phantom was developed for this study, in order to quantify the contribution of independent parameters to the optoacoustic signal (OAS) produced by AuNRs. Analysis of the OAS recorded by 2 US probes demonstrated a direct proportionality between signal amplitude and both AuNR concentration and laser intensity. Moreover, the optimal and maximum duration of laser exposure were determined through a quantitative analysis of progressive degradation of AuNRs under irradiation.