Dynamic intracellular tracking nanoparticles via pH-evoked “off–on” fluorescence

Abstract

Dynamic tracking of nanoparticles in cells faces a big challenge due to fluorescence quenching. Here, the pH-switchable probe spiropyran (SP) was introduced into poly(ethylene glycol) (PEG) via atom transfer radical polymerization (ATRP) to construct expected “off–on” fluorescent nanoparticles. Strong red fluorescence was emitted to efficiently track nanoparticles in cells due to the isomerization of spiropyran to merocyanine in the endosome or lysosome.