A core-shell silica nanosphere for the off–on chemosensor of iron(III) ions and the targeted probe for optical imaging on HeLa cells

Rhodamine B isothiocyanate doped silica-coated (RBITC-SiO2) silica nanoparticles were used as three-dimensional scaffolds for fluorophore organization. Di(2-propylcarboxyl)amine (–NH–COOH) groups were conjugated onto the surface of the RBITC@SiO2 forming a stable water soluble nanospheres (RBITC@SiO2–NH–COOH), which could sensitize Fe3+ ions selectively. State fluorescence measurements allowed us to observe the occurrence of an efficient energy transfer process from coordinated Fe3+ ions to the hosted RBITC resulting the turn-off of the emission of RBITC@SiO2–NH–COOH in water solution. Furthermore, the nanosphere (RBITC@SiO2–NH–COOH) displays enhanced HeLa cells fluorescence imaging in vitro suggesting selective cancer cell payload delivery. It represents a class of novel multifunctional nanoparticles that combines the advantages of active cancer-targeting, compatibility with fluorescence imaging and chemosensors of Fe3+ ions.

Graphical abstractA bifunctional water soluble nanospheres (RBITC@SiO2–NH–COOH) could bind with Fe3+ ions resulting the turn-off of the emission of RBITC@SiO2–NH–COOH in water solution and display enhanced HeLa cells uptake in vitro suggesting selective cancer cell payload delivery.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new water soluble positive charged nanospheres (RBITC@SiO2–NH–COOH) were synthesized and characterized. ► The nanospheres could recognize Fe3+ ions selectively resulting the turn-off of the emission in water solution. ► RHITC@SiO2–NH–COOH can be used as off–on fluorescence sensor. ► The positive charged nanosphere (RBITC@SiO2–NH–COOH) displayed enhanced HeLa cells fluorescence imaging in vitro.