title: Hydrophobic-Sheath Segregated Macromolecular Fluorophores: Colloidal Nanoparticles of Polycaprolactone-Grafted Conjugated Polymers with Bright Far-Red/Near-Infrared Emission for Biological Imaging.
abstract: This article describes molecular design, synthesis and characterization of colloidal nanoparticles containing polycaprolactone-grafted conjugated polymers that exhibit strong far red/near-infrared (FR/NIR) fluorescence for bioimaging. Specifically, we synthesized two kinds of conjugated polymer bottle brushes (PFTB(out)-g-PCL and PFTB(in)-g-PCL) with different positions of the hexyl groups on the thiophene rings. A synthetic amphiphilic block copolymer PCL-b-POEGMA was employed as surfactants to encapsulate PFTB-g-PCL polymers into colloidal nanoparticles (denoted as "nanoREDs") in aqueous media. The chain length of the PCL side chains in PFTB-g-PCL played a critical role in determining the fluorescence properties in both bulk solid states and the colloidal nanoparticles. Compared to semiconducting polymer dots (Pdots) composed of PFTB(out) without grafted PCL, nanoRED(out) showed at least four times higher fluorescence quantum yield (∼20%) and a broader emission band centered at 635 nm. We further demonstrated the application of this new class of nanoREDs for effective labeling of L929 cells and HeLa cancer cells with good biocompatibility. This strategy of hydrophobic-sheath segregated macromolecular fluorophores is expected to be applicable to a broad range of conjugated polymers with tunable optical properties for applications such as bioimaging.
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, Singapore 637459.
authors.forename: Cangjie
authors.initials: C
authors.lastname: Yang
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, Singapore 637459.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Yingdan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, Singapore 637459.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Xu
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, Singapore 637459.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Cao
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, Singapore 637459.
authors.forename: Mingfeng
authors.initials: M
authors.lastname: Wang
mesh_terms: D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D057054:Molecular Imaging / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D045663:Quantum Dots; D013055:Spectrophotometry, Infrared
chemical_list: D005456:Fluorescent Dyes; D011091:Polyesters; D011108:Polymers; C016240:polycaprolactone