The objectives of this study were to demonstrate nonionizing photoacoustic tomography (PAT) of bladders with near-infrared absorbing gold nanocages (GNCs) as an optical-turbid tracer and to investigate the fate of GNCs after photoacoustic imaging.Materials & methods:
The rats' bladders were visualized using PAT after transurethral injection of 2-nM GNCs. The fate of GNCs in the bladders was investigated. Spectroscopic PAT was applied to identify GNC-filled bladders in vivo and study biodistribution ex vivo.Results:
Rats' bladders filled with GNCs were successfully imaged using a PAT system. The photoacoustic amplitude was enhanced by approximately 2240%. Both in vivo and ex vivo PAT results reveal that no accumulation of GNCs in the bladder and kidney was observed, and were validated with inductively coupled plasma mass spectrometry.Conclusion:
The PAT with transurethral injection of GNCs provides two crucial safety features for clinical translation: no radiation exposure and no long-term heavy metal accumulation.