Versatile Synthesis and Fluorescent Labeling of ZIF-90 Nanoparticles for Biomedical Applications

We describe a versatile method for the synthesis and fluorescent labeling of ZIF-90 nanoparticles (NPs). Gram-scale quantities of NPs can be produced under mild conditions, circumventing the need for high temperatures and extended reaction periods required by existing procedures. Monitoring the reaction in situ using UV-vis spectroscopy reveals that ZIF-90 NP nucleation in solution starts within seconds. In addition to reporting a method to reproducibly form sub-100 nm ZIF-90 particles, we show that particles of various sizes can be produced, ranging from 30 to 1000 nm, by altering amine chemistry or reaction temperature. The presence of linker aldehyde groups on the NP surface allows for postsynthetic labeling with amine-functionalized fluorescent dyes, providing utility for imaging within biological systems. In vitro cell studies show that ZIF-90 NPs have a high rate of cellular internalization, provide finite degradation periods of the order of several weeks, and are biocompatible with six different cell lines (>90% viable when incubated with NPs for up to 7 days). These features highlight the potential for use of ZIF-90 nanostructures in bioimaging and targeted drug delivery applications.