Ultrafast photochemistry produces superbright short-wave infrared dots for low-dose in vivo imaging
Harrisson D. A. Santos, Irene Zabala Gutiérrez, Yingli Shen, José Lifante, Erving Ximendes, Marco Laurenti, Diego Méndez-González, Sonia Melle, Óscar G. Calderón, E. López Cabarcos, Núria Fernández, Irene Chaves‐Coira, Daniel Lucena‐Agell, Luis Monge, Mark D. Mackenzie, José Marqués-Hueso, Callum M. S. Jones, Carlos Jacinto, Blanca del Rosal, A. K. Kar, Jorge Rubio‐Retama, Daniel Jaque
Abstract
Abstract Optical probes operating in the second near-infrared window (NIR-II, 1,000-1,700 nm), where tissues are highly transparent, have expanded the applicability of fluorescence in the biomedical field. NIR-II fluorescence enables deep-tissue imaging with micrometric resolution in animal models, but is limited by the low brightness of NIR-II probes, which prevents imaging at low excitation intensities and fluorophore concentrations. Here, we present a new generation of probes (Ag 2 S superdots) derived from chemically synthesized Ag 2 S dots, on which a protective shell is grown by femtosecond laser irradiation. This shell reduces the structural defects, causing an 80-fold enhancement of the quantum yield. PEGylated Ag 2 S superdots enable deep-tissue in vivo imaging at low excitation intensities (<10 mW cm −2 ) and doses (<0.5 mg kg −1 ), emerging as unrivaled contrast agents for NIR-II preclinical bioimaging. These results establish an approach for developing superbright NIR-II contrast agents based on the synergy between chemical synthesis and ultrafast laser processing.