We report newly synthesized fluorescence resonance energy transfer (FRET)-based green-, red-, and near-infrared (NIR)-emitting polymer dot (Pdot) probes. Fluorescent Pdots (∼60 nm) were prepared with a green-emissive conjugated polymer (PPDT-P, donor) alone or mixing the donor with a red- or NIR-emitting fluorophore (T-DCS or ITIC, acceptor), where an optically inert matrix polymer [poly(styrene-co-maleic anhydride)] was mixed together to minimize the aggregation-caused quenching by diluting the fluorophores and surface functionalization for further bioconjugation with antibodies for active targeting. Highly fluorescent green-emissive PPDT-P Pdots were prepared with a photoluminescence (PL) quantum efficiency of ∼30% and the FRET-mediated red and NIR PL was intensified by 5.3-8.5 times (with high FRET ratios of ∼9) via the efficient energy transfer (FRET efficiency of 80-98%) and antenna effect, compared with the signals obtained via direct excitation of the fluorophores in Pdots. All three types of Pdot/antibody conjugates were simultaneously immunostained to COS-7 cells (showing minimal cross-reactivity), reducing the tedious sequential immunostaining process to a single step. Finally, we obtained high-contrast three-color cell images with little spectral leakthrough by exciting all the probes simultaneously at a single wavelength at 405 nm without the need for a complicated or expensive multiple-excitation setup.
Bibliographical noteFunding Information:
This work was supported by the Korea University Grant and the National Research Foundation (NRF) of Korea (2019R1A2C2085290, 2017K2A9A2A12000315, and 2019R1A6A1A11044070). This work was supported by the Institute for Basic Science (IBS-R023-D1) for H.-C.K., M.K., and S.-H.S. M.A.U. acknowledges the Juan De La Cierva postdoctoral fellowship.
© 2020 American Chemical Society.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Materials Chemistry