Functional Dye-Doped Silica Nanoparticles for Bioimaging, Diagnostics and Therapeutics

This paper describes the design, synthesis and biological application of dye-doped silica nanoparticles (DDSNs). About 80 nm size monodisperse FITC (fluorescein isothiocyanate) doped silica nanoparticles were synthesized using water-in-oil (W/O) microemulsion method. The DDSN surface was then modified to attach amine functional groups. The complete synthesis of amine modified DDSNs was carried out in a single pot at room temperature. To demonstrate bioimaging applications, DDSNs were modified with TAT (a cell penetrating peptide, CPP) and folic acid (a vitamin, also called folate). TAT conjugated DDSNs were treated with A-549 cells and an effective labelling was observed. Folate conjugated DDSNs were targeted to two types of cells, human lung adenocarcinoma (A-549) and human dermal fibroblast cells. A-549 cells over express folate receptors and as expected, an extensive labelling was observed with A-549 cells when compared with normal fibroblast cells. Laser scanning confocal images clearly showed that folate conjugated DDSNs were internalized by A-549 cells.