Fig. 11. Applications of bright NPs for biosensing. (A) Top: FRET based molecular probe showing that the applications are limited to distances around the Förster radius. Bottom: FRET based nanoprobe where large number of donors are coupled due to excitation energy transfer (small yellow arrows) in order to ensure efficient transfer to a single acceptor. (B) Schematic Illustration of Pdot from donor–acceptor conjugated polymer. (C) Photographs of PFOBT36SeTBT5 Pdots with the addition of ClO⁻ taken under normal laboratory lighting and illumination with a UV light at 365 nm. (B and C) – Reproduced with permission from ref. 158. Copyright American Chemical Society. (D) DNA-functionalized dye-loaded polymeric nanoparticle (NP-Probe) for FRET-based detection of nucleic acids by stand displacement principle. R18 and its bulky counterion F5-TPB are also shown. (E) Fluorescence spectral response of NP-probe to the growing concentrations of the nucleic acid target. (F) Colour response of surface-immobilized NP-probe to the nucleic acid target (100 pM) at the single-particle level. (D–F) – Reproduced with permission from ref. 35. Copyright American Chemical Society.