Ruthenium tris(2,2′-bipyridyl) complex encapsulated in nanosized faujasite zeolite as intracellular localization tracer

Abstract

Designing zeolites for medical applications is a challenging task that requires introducing new functionalities without altering the intrinsic properties such as morphology, crystallinity, colloidal stability, surface charge, and porosity. Herein, we present the encapsulation of luminescent ruthenium-tris(2,2′-bipyridyl) complex in faujasite (FAU) zeolite nanocrystals (Ru(bpy)3-FAU) and their use as an intracellular localization tracer. Upon exciting the Ru(bpy)3-FAU zeolite at 450 nm, the sample gives rise to an orange-red emission at 628 nm, thus permitting its use for cellular imaging and localization of the zeolite nanoparticles. The nanosized Ru(bpy)3-FAU zeolite is characterized in terms of size, charge, crystallinity, morphology, porosity, thermal stability, and sorption capacity. The potential toxicity of Ru(bpy)3-FAU on U251-MG glioblastoma cells was evaluated. A safe concentration (50–100 µg/ml) for the Ru(bpy)3-FAU zeolite is identified. The luminescent properties of the ruthenium complex confined in the zeolite nanocrystals allow their localization in the U251-MG cells with a main accumulation in the cytoplasm. The Ru(bpy)3-FAU nanosized zeolite is a potential candidate for biological applications for being stable, safe, capable of loading respiratory gases, and easily probed in the cells owing to its luminescent properties.