Highly Stable and NIR Luminescent Ru–LPMSN Hybrid Materials for Sensitive Detection of Cu²⁺ in Vivo

Herein, new near-infrared (NIR) luminescent ruthenium complexes were prepared for detecting Cu2+ ions. Then, ruthenium complex hybrid nanomaterials (Ru–LPMSNs) were fabricated successfully by imbedding the ruthenium complex into mesoporous silica nanoparticles. Benefiting from the novel large-pore mesoporous structure and good adsorbility of LPMSNs, Ru–LPMSN hybrid materials showed a significantly enhanced fluorescence intensity and stability. NIR fluorescence of Ru–LPMSNs was rapidly quenched by Cu2+ ions. Ru–LPMSNs also showed high Cu2+ ion selectivity and sensitivity as a sensor. The detection limit of Cu2+ ions was 10 nM with a wide linear relationship between the fluorescence intensity of Ru–LPMSNs and the concentration of Cu2+ ions. The mechanism of fluorescence quenching might be that the combination of the ruthenium complex and Cu2+ ions constrained the photoinduced electron-transfer process. Furthermore, Ru–LPMSNs dramatically increased the fluorescence signals in cells and achieved Cu2+-ion detection. Ru–LPMSNs had different tissue affinities and could monitor distribution of exogenous Cu2+ ions in vivo. Moreover, Ru–LPMSNs realized direct and rapid detection of Cu2+-ion content in serum. These results indicated the potential applications of the prepared nanomaterials as Cu2+ detection agents.