Synthesis of PEGylated gold nanorods (Au NRs) as absorption nanoprobes for near-infrared optical imaging

In this contribution, we show that Au NRs functionalized with PEG molecules can be used as absorption nanoprobes for near-infrared imaging in live animals. We have found that the contrast signal of the in vivo image is dependent upon the transmission ability of the NIR light interacting with the different aspect ratios of Au NRs. Our study was focused on absorption in vivo imaging at 700 nm, which is within the transmission window of the skin. NIR absorption in vivo imaging was carried out by subcutaneous injection of mice with PEGylated Au NRs that have a LSPR around 700 nm. The formulation showed strong contrast signals under the tissues upon irradiation with NIR light. More importantly, our theoretical calculation suggested that the high contrast signals from the PEGylated Au NRs were generated via the NIR light absorption of the Au NRs within the tissue