Increasing depth penetration in biological tissue imaging using 808-nm excited Nd 3+ /Yb 3+ /Er 3+ -doped upconverting nanoparticles

Abstract

Ytterbium (Yb3+)-sensitized upconverting nanoparticles (UCNPs) are excited at 975 nm causing relatively high absorption in tissue. A new type of UCNPs with neodymium (Nd3+) and Yb3+ codoping is excitable at a 808-nm wavelength. At this wavelength, the tissue absorption is lower. Here we quantify, both experimentally and theoretically, to what extent Nd3+-doped UCNPs will provide an increased signal at larger depths in tissue compared to conventional 975-nm excited UCNPs.