Many fluorophores, such as indocyanine green (ICG), have poor photostability and low photothermal efficiency hindering their wide application in photoacoustic (PA) tomography. In the present study, a supramolecular assembly approach was used to develop the hybrid nanoparticles (Hy NPs) of ICG and porous silicon (PSi) as a novel contrast agent for PA tomography. ICG was assembled on the PSi NPs to form J-aggregates within 30 min. The Hy NPs presented a red-shifted absorption, improved photothermal stability, and enhanced PA performance. Furthermore, 1-dodecene (DOC) was assembled into the NPs as a ‘nanospacer’, which enhanced non-radiative decay for increased thermal release. Compared to the Hy NPs, adding DOC into the Hy NPs (DOC-Hy) increased the PA signal by 83%. Finally, the DOC-Hy was detectable in PA tomography at 1.5 cm depth in tissue phantom even though its concentration was as low as 6.25 µg/mL, indicating the potential for deep tissue PA imaging.

中文翻译：

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将荧光团 J-聚集体与纳米间隔物组装到介孔纳米粒子上以增强光声成像

许多荧光团，例如吲哚菁绿（ICG），光稳定性差和光热效率低，阻碍了它们在光声（PA）断层扫描中的广泛应用。在本研究中，采用超分子组装方法开发了 ICG 和多孔硅 (PSi) 的混合纳米颗粒 (Hy NP)，作为 PA 断层扫描的新型造影剂。 ICG 在 PSi NP 上组装，在 30 分钟内形成 J 聚集体。 Hy NPs 呈现出红移吸收、改善的光热稳定性和增强的 PA 性能。此外，1-十二碳烯（DOC）作为“纳米间隔物”组装到纳米颗粒中，增强了非辐射衰变，从而增加了热释放。与 Hy NP 相比，在 Hy NP 中添加 DOC (DOC-Hy) 使 PA 信号增加了 83%。最后，尽管 DOC-Hy 的浓度低至 6.25 µg/mL，但在 PA 断层扫描中可在组织模型中 1.5 cm 深度处检测到 DOC-Hy，这表明其具有深部组织 PA 成像的潜力。