Fluorescent probe-encapsulated smart nanohydrogel to enhance sensitivity toward hydrogen peroxide in living cells

In this study, a fluorescent probe-encapsulated reduction-sensitive smart nanohydrogel as a new nanosensor was fabricated. The nanohydrogel was prepared via distillation-precipitation polymerization by using N, N ′-bis(acryloyl) cystinamide both as the monomer and crosslinker. Besides, red fluorescent hydrophobic peroxyresorufin-1 (PR1) probe for H 2 O 2 was employed and encapsulated into the nanohydrogel. We found that the nanohydrogel not only can encapsulate a large number of hydrophobic fluorescent probes with high loading capacity, but also can avoid the aggregation of hydrophobic fluorescent probes. Confocal laser fluorescence imaging of H 2 O 2 in HeLa cells demonstrated that the PR1-encapsulated nanohydrogel allows efficient delivery of PR1 probe into living HeLa cells. In cytoplasm, the nanohydrogels reduced and degraded by glutathione, and the PR1 probes released from the nanohydrogel were enriched and concentrated in some local regions, resulting in enhanced imaging of endogenous H 2 O 2 . This work provides a facile nanohydrogel-assisted probe-encapsulation strategy, which is also applicable to multiple fluorescent probes, thus enabling imaging of diverse endogenous bioactive molecules. • A new fluorescent probe-encapsulated nanohydrogel (PR1@nanogel) was fabricated. • The nanohydrogel possess reduction-sensitivity. • The nanohydrogel can avoid the aggregation of fluorescent probes. • Imaging of endogenous H 2 O 2 in HeLa cells with the PR1@nanogel was achieved.