Photoacoustic molecular imaging using combined acupuncture and gold nanorods as a composite contrast agent

Abstract

In this study, we developed a novel photoacoustic imaging technique based on poly (ethyleneglycol)-coated (PEGylated) gold nanorods (PEG-GNRs) (as the contrast agent) combined with traditional Chinese medicine (TCM) acupuncture (as the auxiliary method) for quantitatively monitoring contrast enhancement in the vasculature of a mouse brain in vivo. This study takes advantage of the strong near-infrared absorption (peak at ~700nm) of GNRs and the ability to adjust the hemodynamics of acupuncture. Experimental results show that photoacoustic tomography (PAT) successfully reveals the optical absorption variation of the vasculature of the mouse brain in response to intravenous administration of GNRs and acupuncture at the Zusanli acupoint (ST36) both individually and combined. The quantitative measurement of contrast enhancement indicates that the composite contrast agents (integration of acupuncture and GNRs) would greatly enhance the photoacoustic imaging contrast. The quantitative results also have the potential to estimate the local concentration of GNRs and even the real-time effects of acupuncture.