Chiral Core–Shell Upconversion Nanoparticle@MOF Nanoassemblies for Quantification and Bioimaging of Reactive Oxygen Species in Vivo

In this study, a hybrid nanoassembly consisting of an upconversion nanoparticle (UCNP) core and a zeolitic imidazolate framework-8 (ZIF) shell encapsulated with chiral NiSx NPs (denoted as UCNP@ZIF-NiSx) were fabricated. The UCNP@ZIF-NiSx nanoassemblies showed an intense circular dichroism (CD) signal at 440 and 530 nm, whereas the upconversion luminescence (UCL) signal of the UCNPs at 540 nm were quenched by NiSx NPs and the UCL signal at 660 nm was almost unchanged. By taking advantage of the chiral-optical and fluorescent signals, the dual mode nanoassemblies can be used for quantitively monitoring reactive oxygen species (ROS), with hydrogen peroxide (H₂O₂) as the proof-of-concept target in living cells. The experimental results revealed that UCNP@ZIF-NiSx has been changed into UCNP@ZIF with degradation of NiSx during the detection process. Noticeably, quantitative and selective detection of ROS was successfully carried out in vivo. This strategy highlights the potential of chiral nanoassemblies for ROS detection, which opens up a new avenue to develop the toolbox of chiral nanomaterials for biomedical and biological analysis.