Materials Science and Engineering Program, University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093, United States.
Department of Nanoengineering, University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093, United States.
ACS Appl Mater Interfaces. 2021 Apr 7;13(13):14974-14984. doi: 10.1021/acsami.1c00993. Epub 2021 Mar 24.
Photoacoustic (PA) imaging holds great promise as a noninvasive imaging modality. Gold nanorods (GNRs) with absorption in the second near-infrared (NIR-II) window have emerged as excellent PA probes because of their tunable optical absorption, surface modifiability, and low toxicity. However, pristine GNRs often undergo shape transition upon laser illumination due to thermodynamic instability, leading to a reduced PA signal after a few seconds of imaging. Here, we report monodisperse GNR-melanin nanohybrids where a tunable polydopamine (PDA) coating was conformally coated on GNRs. GNR@PDAs showed a threefold higher PA signal than pristine GNRs due to the increased optical absorption, cross-sectional area, and thermal confinement. More importantly, the PA signal of GNR@PDAs only decreased by 29% during the 5 min of laser illumination in the NIR-II window, while significant attenuation (77%) was observed for GNRs. The GNR@PDAs maintained 87% of its original PA signal even after 10 min of laser illumination. This PDA-enabled strategy affords a rational design for robust PA imaging probes and provides more opportunities for other types of photomediated biomedicines, such as photothermal and photodynamic regimens.
光声（PA）成像是一种很有前途的非侵入性成像方式。由于其可调谐的光学吸收、表面可修饰性和低毒性，在近红外二区（NIR-II）有吸收的金纳米棒（GNRs）已成为出色的 PA 探针。然而，由于热力学不稳定性，原始 GNRs 在激光照射下经常会发生形状转变，导致成像几秒钟后 PA 信号降低。在这里，我们报告了单分散 GNR-黑色素纳米杂化体，其中在 GNR 上通过共形涂层形成了可调的聚多巴胺（PDA）涂层。由于增加了光学吸收、横截面积和热限制，GNR@PDAs 的 PA 信号比原始 GNRs 高了三倍。更重要的是，在 NIR-II 窗口中激光照射的 5 分钟内，GNR@PDAs 的 PA 信号仅下降了 29%，而 GNRs 则观察到明显的衰减（77%）。即使在 10 分钟的激光照射后，GNR@PDAs 仍保持其原始 PA 信号的 87%。这种 PDA 实现的策略为稳健的 PA 成像探针提供了合理的设计，并为其他类型的光介导的生物医学提供了更多机会，例如光热和光动力疗法。
