Thienoisoindigo‐based semiconducting polymer with a strong near‐infrared absorbance is synthesized and its water‐dispersed nanoparticles (TSPNs) are investigated as a contrast agent for photoacoustic (PA) imaging in the second near‐infrared (NIR‐II) window (1000–1350 nm). The TSPNs generate a strong PA signal in the NIR‐II optical window, where background signals from endogenous contrast agents, including blood and lipid, are at the local minima. By embedding a TSPN‐containing tube in chicken‐breast tissue, an imaging depth of more than 5 cm at 1064 nm excitation is achieved with a contrast‐agent concentration as low as 40 µg mL⁻¹. The TSPNs under the skin or in the tumor are clearly visualized at 1100 and 1300 nm, with negligible interference from the tissue background. TSPN as a PA contrast in the NIR‐II window opens new opportunities for biomedical imaging of deep tissues with improved contrast.

中文翻译：

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半导体聚合物纳米颗粒，用于在第二个近红外窗口中进行厘米深的光声成像

合成了具有强近红外吸收性的基于Thienoisoindigo的半导体聚合物，并研究了其水分散纳米颗粒（TSPN）作为第二近红外（NIR-II）窗口中光声（PA）成像的造影剂。 1350 nm）。TSPN在NIR-II光学窗口中产生很强的PA信号，其中来自内源性造影剂（包括血液和脂质）的背景信号处于局部最小值。通过将包含TSPN的试管嵌入鸡胸组织中，在1064 nm激发下成像深度超过5 cm，造影剂浓度低至40 µg mL ^-1。皮下或肿瘤中的TSPN在1100和1300 nm处清晰可见，而来自组织背景的干扰可忽略不计。TSPN作为NIR-II窗口中的PA造影剂，为对比度更高的深部组织生物医学成像打开了新的机遇。