title: Donor-acceptor-donor fluorene derivatives for two-photon fluorescence lysosomal imaging.
abstract: As part of a strategy to achieve large two-photon absorptivity in fluorene-based probes, a series of donor-acceptor-donor (D-A-D) type derivatives were synthesized and their two-photon absorption (2PA) properties investigated. The synthesis of D-A-D fluorophores was achieved by efficient preparation of key intermediates for the introduction of central electron acceptor groups. To accomplish the synthesis of two of the new derivatives, a high-yield method for a one-step direct dibromomethylation of phenyl sulfide was developed. The linear and nonlinear optical properties, including UV-vis absorption, fluorescence emission, fluorescence anisotropy, and two-photon absorption (2PA), of the new D-A-D compounds were measured and compared to their D-A or D-D counterparts. Fully conjugated acceptor moieties in the center of the D-A-D fluorophore led to the greatest increase in the 2PA cross section, while weakly conjugated central acceptors exhibited only a modest increase in the 2PA cross section relative to D-A diploar analogs. Encapsulation of the new probes in Pluronic F 108NF micelles, and subsequent incubation in HCT 116 cells, resulted in very high lysosomal colocalization (>0.98 colocalization coefficient) relative to commercial Lysotracker Red, making the micelle-encapsulated dyes particularly attractive as fluorescent probes for two-photon fluorescence microscopy lysosomal imaging.
authors.affiliation: Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, Florida 32816-2366, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Yao
authors.forename: Hyo-Yang
authors.initials: HY
authors.lastname: Ahn
authors.forename: Xuhua
authors.initials: X
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Fu
authors.forename: Eric W
authors.initials: EW
authors.lastname: Van Stryland
authors.forename: David J
authors.initials: DJ
authors.lastname: Hagan
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Belfield
mesh_terms: D005449:Fluorenes / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis*; D045325:HCT116 Cells; D006801:Humans; D008247:Lysosomes / Q000737:chemistry*; D008823:Micelles; D057054:Molecular Imaging
chemical_list: D005449:Fluorenes; D005456:Fluorescent Dyes; D008823:Micelles