title: Reversible photoswitching of spiropyran-conjugated semiconducting polymer dots.
abstract: Semiconducting polymer dots (Pdots) recently have emerged as a new class of ultrabright fluorescent probes with promising applications in biological detection and imaging. We developed photoswitchable Pdots by conjugating photochromic spiropyran molecules onto poly[9,9-dioctylfluorenyl-2,7-diyl)-co-1,4-benzo-{2,1'-3}-thiadiazole)] (PFBT). The modulation of fluorescence was achieved by ultraviolet irradiation, which converted spiropyran into its visible-absorbing merocyanine form. The merocyanine efficiently quenched the fluorescence of PFBT via Förster resonance energy transfer (FRET). We then reversed the quenching by subsequent irradiation with visible light to get back the fluorescence of PFBT. This FRET-based photomodulation of Pdot fluorescence could be repeated multiple times. We next conjugated biomolecules onto the surface of these photoswitchable Pdots and demonstrated their specific cellular and subcellular labeling to different types of cells without any noticeable nonspecific binding. We anticipate these photoswitchable and biocompatible Pdots will be useful in developing bioimaging techniques in the future.
authors.affiliation: Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
authors.forename: Yang-Hsiang
authors.initials: YH
authors.lastname: Chan
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Gallina
authors.forename: Xuanjun
authors.initials: X
authors.lastname: Zhang
authors.forename: I-Che
authors.initials: IC
authors.lastname: Wu
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Jin
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Chiu
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D005449:Fluorenes / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D007211:Indoles / Q000737:chemistry*; D008027:Light; D061986:MCF-7 Cells; D057054:Molecular Imaging; D009574:Nitro Compounds / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012666:Semiconductors; D013050:Spectrometry, Fluorescence; D019809:Streptavidin / Q000737:chemistry
chemical_list: D001578:Benzopyrans; D005449:Fluorenes; D007211:Indoles; D009574:Nitro Compounds; D011108:Polymers; C545278:poly(9,9'-bis(6''-N,N,N-trimethylammonium)hexyl)fluorene-co-alt-4,7-(2,1,3-benzothiadiazole) dibromide; C088184:spiropyran; D019809:Streptavidin