Multiple Dye Doped Core-Shell Silica Nanoparticles: Outstanding Stability and Signal Intensity Exploiting FRET Phenomenon for Biomedical Applications

We present a one-pot synthesis of core-shell silica nanoparticles (SiNPs) as a novel fluorescent probe for biological applications. SiNPs were doped with a different number of dyes to ensure high efficiency Fluorescence Resonance Energy Transfer (FRET). Dyes are individually entrapped in the silica core without a covalent bonding between them. Thanks to the strong interconnection achieved inside the core, a FRET with efficiency up to 86% was obtained. Nanoparticles called NTB530, NTB575 and NTB660 contain two, three and four different dyes respectively. Nanoparticles can be excited with a common blue laser and characterized by a long Stokes Shift up to the near-IR emission. Photostability, tested under continuous irradiation with a mercury lamp, showed higher stability of our Nanoparticles compared to commercial dyes like Fluorescein and R-Phycoerythrin. To prove the potential application of our Nanoparticle in flow-cytometry, they were conjugated with Anti-Human CD8 antibody and tested in comparison with commercial ones