Gold nanoshell-based photoacoustic imaging application in biomedicine

Gold nanoshell was used as a new contrast-enhancing agent for photoacoustic tomography. Gold nanoshells are concentric sphere nanoparticles consisting of a dielectric silica core and a gold shell. By varying the relative thickness of the core and shell layers, the plasmon-derived optical resonance of gold can be dramatically shifted in wavelength from the visible region into the infrared over a wavelength range that spans the region of highest physiological transmissivity. In this experimentation, nanoshells with 100 nm silica core diameter and 20 nm gold shells thickness has an optical absorption peak at 800 nm and deep penetrating pulse laser of 800 nm were employed to image the the vasculature architecture of a rat brain in vivo. Here we accurately imaged rat brain structures with gold nanoshell contrast agents. We also mapped the distribution of gold nanoshell in the in vivo rat brain. This experiment results demonstrated that nanoshell accumulation is greatly enhanced NIR optical contrast in the vasculature. Nanoshell-based photoacoustic imaging technique would be applied in biomedicine extensively. The further development of photoacoustic tomography to characterize and monitor the accumulation of nanoshells in vivo will be applied to the detection of tumors in situ as well as to guiding nanoshell-based thermal tumor therapy. Gold nanoshell can potentially provide an accurate noninvasive method, use as imaging contrast agents, to employ in functional photoacoustic at molecular and cellular level.