Polymeric entrapped thiol-coated gold nanorods: Cytotoxicity and suitability as molecular optoacoustic contrast agent

The behaviour of polymeric entrapped thiol-coated GNRs in culture medium under biological conditions was analysed. The in vitro cytotoxicity was studied by a Colony Forming Efficiency assay on immortalized mouse fibroblasts (Balb/3T3) obtaining a dose-effect relationship in which a half inhibitory concentration (IC50) was 20.3µM. The suitability of the new nanomaterial as an optoacoustic contrast agent was investigated in phantom studies using a hardware platform suitable for retrieving clinically relevant data. Spherical alginate phantoms containing GNR-2-PNPs at different concentrations were synthesized and the optoacoustic signal amplitudes were measured as a function of concentration. Signals could be obtained with satisfying signal-to-noise ratio (SNR) down to concentrations of 11 µM corresponding to subtoxic concentration in our in vitro model. The nanomaterial proved to be a suitable and promising contrast agent for different optoacoustic imaging modalities including multispectral approaches.