Surface-engineered mesoporous silica particles with luminescent, cytocompatible and targeting properties for cancer cell imaging

To develop a novel cancer cell imaging approach, we fabricated surface-engineered mesoporous silica (MPS) particles with multi-functionalities. Specifically, mechanochemically-treated europium(III)-doped MPS (Eu:MPS) particles were prepared, and a folate N-hydroxysuccinimidyl ester (FA-NHS) molecule was immobilized on the particle surface as a targeting ligand for specific types of cells. With the mechanochemical treatment, the siloxane bonds were changed to show better luminescence quantum efficiency as revealed by 29Si-NMR and photoluminescence spectroscopy, suggesting interaction changes between the silica framework structures and the doped Eu ions. Furthermore, the mechanochemically-treated particles immobilized with FA-NHS specifically bind to the cancer cells and the subsequent uptake by the cells was in situ observed using time-lapse optical microscopy. The particles did not exhibit any toxicity in the cellular proliferation stages. The particles after the binding and uptake also showed intense luminescence from the cells at a culture time of 24 h, demonstrating a clear imaging ability along with all the cellular shapes. Therefore, the present surface-engineered luminescent particles will be used for specific cancer targeting and imaging purposes.