Lanthanide/Cu2-xSe Nanoparticles for Bacteria-Activated NIR-II Fluorescence Imaging of Infection

A material system enabling specific NIR-II fluorescence imaging of Gram-positive bacteria is described. The material system is based on the electrostatic binding of Cu2-xSe and vancomycin-modified NaGdF4:Nd,Yb@NaGdF4 downconversion nanoparticles (DCNPs), the fluorescence of which is weak owing to the spectral overlap of Cu2-xSe absorption with the DCNP NIR emission. The presence of Gram-positive bacteria precisely disconnects the bond between vancomycin-modified DCNPs and Cu2-xSe, thus enabling a strong fluorescent signal. In vivo studies show that the material system can be specifically activated at the site of Gram-positive bacterial infection but is essentially nonfluorescent in the area of Gram-negative bacterial infection.

Automated summary

This study describes a material system that enables specific near-infrared-II (NIR-II) fluorescence imaging of Gram-positive bacteria. The material system is based on the electrostatic binding of copper selenide (Cu2-xSe) and vancomycin-modified nanoparticles, which are weakly fluorescent due to spectral overlap. The presence of Gram-positive bacteria disconnects the bond between the nanoparticles, resulting in a strong fluorescent signal. In vivo studies demonstrate that the material system can specifically detect Gram-positive bacterial infection while showing little fluorescence in the area of Gram-negative bacterial infection.