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Nature Communications

  • Preclinical

Ultrafast photochemistry produces superbright short-wave infrared dots for low-dose in vivo imaging

Authors Harrisson D. A. Santos, Irene Zabala Gutiérrez, Yingli Shen, José Lifante, Erving Ximendes, Marco Laurenti, Diego Méndez-González, Sonia Melle, Oscar G. Calderón, Enrique López Cabarcos, Nuria Fernández, Irene Chaves-Coira, Daniel Lucena-Agell, Luis Monge, Mark D. Mackenzie, José Marqués-Hueso, Callum M. S. Jones, Carlos Jacinto, Blanca del Rosal, Ajoy K. Kar, Jorge Rubio-Retama and Daniel Jaque


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 (Ag2S superdots) derived from chemically synthesized Ag2S 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 Ag2S superdots enable deep-tissue in vivo imaging at low excitation intensities (<10 mW cm−2) and doses (<0.5 mg kg−1), emerging as unrivalled 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.

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