Photoacoustic imaging is a noninvasive biomedical imaging technology developed recently. And the research on organic conjugated polymer as contrast agent becomes one of the hot topics in the field of photoacoustic imaging. Polydiacetylene is a biocompatible conjugated polymeric layered crystal. At the meantime, the fluorescence of blue-phase polydiacetylene was sufficiently forbidden, providing it an excellent photo-thermal conversion performance. However, it has the poor stability and relatively short wavelength. Here, we develop the novel blue-phase polydiacetylene composites with high stability and long wavelength by intercalating Gd3+ ions and optimizing the composite crystalline structures. The non-covalently connected micelles (NCCM) with diacetylenic acid monomers and Gd3+ ions were first fabricated. The micelles then underwent annealing process to achieve the nearly defect-free intercalated composite crystal structure, in which a layer of Gd3+ ions was intercalated in between each two diacetylenic acid bilayers to tether almost all of the carboxyl groups of diacetylenic acid. After topological polymerization, the resultant PDA-Gd3+ composites retained the perfectly intercalated structure, enabling not only the increase in the melting temperature of the crystalline domains but also the reversible thermochromism of the composites. Moreover, the light absorption wavelength of the composite was increased and the extinction coefficient was enhanced due to the raise in the effective conjugation length of PDA. Therefore, the resultant composite has the strong near-infrared absorption and the excellent photoacoustic imaging performance. And the Gd3+ ion incorporated inside the composites are extremely less cytotoxic and have excellent magnetic resonance imaging contrast enhancement ability as well.

Polydiacetylene-Gd3+ nanosheet for photoacoustic/magnetic resonance dual-modal imaging

256th National Meeting (2018)

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