Polymeric Self-Assemblies with Boron-Containing Near-Infrared Dye Dimers for Photoacoustic Imaging Probes

Koji Miki, Akane Enomoto, Tatsuhiro Inoue, Tatsuya Nabeshima, Sousuke Saino, Soji Shimizu, Hideki Matsuoka, Kouichi Ohe

    Research output: Contribution to journalArticlepeer-review

    34 Citations (Scopus)


    Polymers containing pyrrolopyrrole aza-BODIPY (PPAB) and thiophene-bridged BODIPY dimers (TBD) having poly(ethylene glycol) (PEG) or PEGylated hyaluronic acid (HA) were prepared by facile conjugation approaches. Self-assemblies consisting of TBD-conjugated polymers more efficiently generated photoacoustic (PA) signals than PPAB-PEG conjugate upon irradiation with near-infrared pulsed laser light. Among dye-conjugated polymers examined, TBD-HA-PEG conjugates efficiently generated photoacoustic signals, 1.49-1.83 times stronger than that of commercially available indocyanine green (ICG). We found that the following two factors are essential to enhance PA signals from self-assemblies: (1) the formation of strongly interacting TBD aggregates and (2) enhancement of the elastic modulus of self-assemblies by conjugating TBDs with HA. TBD-conjugated HA derivatives circulated in blood vessels for a longer time (15.6 ± 4.9% injected dose (ID) in blood 24 h after injection) and more specifically accumulated in tumor tissues (17.8 ± 3.5% ID/g in tumor 24 h after injection) than ICG-conjugated HA derivatives, visualizing a tumor site more clearly. The cell uptake experiment of dye-HA conjugates indicates that ICG-conjugated polymers internalized into cells or merged with cell walls to emit strong fluorescence, while TBD-conjugated polymers were not internalized into cells. Because the disassembly of the TBD-conjugated HA derivatives is suppressed, aggregated TBDs emit weak fluorescence but efficiently generate strong PA signals in tumor tissues.

    Original languageEnglish
    Pages (from-to)249-256
    Number of pages8
    Issue number1
    Publication statusPublished - Jan 9 2017

    All Science Journal Classification (ASJC) codes

    • Bioengineering
    • Biomaterials
    • Polymers and Plastics
    • Materials Chemistry


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