title: Highly emissive PEG-encapsulated conjugated polymer nanoparticles.
abstract: A novel bioimaging probe based on a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,1,3-benzoxadiazole) (PFBD), is demonstrated. Transfer of the hydrophobic polymer into water using a short chain poly(ethylene glycol) (PEG) resulted in conjugated polymer nanoparticles (PEG-PFBD) with a fluorescence quantum yield of 46%. The PEG-PFBD nanoparticles possessed several desirable structural and photophysical properties, such as colloidal stability in a broad range of pH values, sub-20 nm particle size, the presence of surface chemical functionality, as well as desirable excitation and emission spectra, for bioimaging applications. PEG-PFBD nanoparticles were conjugated with cyclic RGDfK targeting peptide for labeling of membrane α(V)β(3) integrin receptors on live HT-29 adenocarcinoma cells. Single nanoparticle microscopy revealed that the PEG-capped PFBD nanoparticles exhibit at least ten times higher emitted photon counts than single quantum dots (QD655) of comparable size. In addition, Fluorescence Lifetime Imaging Microscopy (FLIM) of single PEG-PFBD nanoparticles revealed that the nanoparticles display a clearly resolvable single nanoparticle fluorescence lifetime.
authors.affiliation: Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 3 Research Link, Singapore 117602.
authors.forename: Yuqiong
authors.initials: Y
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Nikodem
authors.initials: N
authors.lastname: Tomczak