title: Nano-confined squaraine dye assemblies: new photoacoustic and near-infrared fluorescence dual-modular imaging probes in vivo.
abstract: For the purpose of near-infrared (NIR) fluorescence and photoacoustic (PA) tomography dual-modular imaging, self-assembly of squaraine (SQ) dyes is constructed in the hydrophobic phospholipid bilayers of liposomes (SQ⊂L) with variable mixing ratios of SQ and phospholipids from 1:500 to 1:10 (w/w). When doping minimal amounts of SQ, molecularly dispersed SQ in bilayers shows remarkable fluorescence. Interesting, the PA signal is enhanced with increase of SQ in the nanoconfined bilayer region, which is attributed to the formation of SQ-based H-aggregates and enhanced thermal conversion efficiency (η). SQ⊂L shows satisfactory chemical and thermal stabilities and photobleaching resistance. SQ⊂L is well-distributed in the cytoplasm of MCF-7 cells and its fluorescence signal remains for 7 days without dramatic quenching owing to the good stability of SQ⊂L. Furthermore, SQ⊂L is subjected to in vivo NIR fluorescence imaging to evaluate the whole-body biodistribution in organ level. Particularly, PA imaging with deeper tissue penetration capability is utilized to investigate the heterogeneous distribution SQ⊂L inside solid tumor. The majority of SQ⊂L are enriched in the area where the blood vessels are generated, implying that the liposomal nanocarriers exhibit lower tumor tissue penetration capability after the vascular leakage. This result is validated by histological examination of tumor tissue in parallel.
authors.affiliation: CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology (NCNST) , No. 11 Beiyitiao, Zhongguancun, Haidian District, Beijing, 100190, China.
authors.forename: Di
authors.initials: D
authors.lastname: Zhang
authors.forename: Ying-Xi
authors.initials: YX
authors.lastname: Zhao
authors.forename: Zeng-Ying
authors.initials: ZY
authors.lastname: Qiao
authors.forename: Ulrich
authors.initials: U
authors.lastname: Mayerhöffer
authors.forename: Peter
authors.initials: P
authors.lastname: Spenst
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Li
authors.forename: Frank
authors.initials: F
authors.lastname: Würthner
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
mesh_terms: D000818:Animals; D003503:Cyclobutanes / Q000737:chemistry* / Q000493:pharmacokinetics; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D021621:Imaging, Three-Dimensional; D007259:Infrared Rays; D008081:Liposomes; D061986:MCF-7 Cells; D008325:Mammary Neoplasms, Experimental / Q000175:diagnosis; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures; D061848:Optical Imaging / Q000379:methods*; D055620:Optical Phenomena; D010636:Phenols / Q000737:chemistry* / Q000493:pharmacokinetics; D010743:Phospholipids / Q000737:chemistry; D061088:Photoacoustic Techniques / Q000379:methods*
chemical_list: D003503:Cyclobutanes; D005456:Fluorescent Dyes; D008081:Liposomes; D010636:Phenols; D010743:Phospholipids; C480596:squaraine