In vivo near-infrared (NIR) photoacoustic imaging (PAI) studies using novel contrast agents require validation, often via fluorescence imaging. Bioconjugation of NIR dyes to proteins is a versatile platform to obtain contrast agents for specific biomedical applications. Nonfluorescent NIR dyes with higher photostability present advantages for quantitative PAI, compared to most fluorescent NIR dyes. However, they don’t provide a fluorescence signal required for fluorescence imaging. Here, we designed a hybrid PA-fluorescent contrast agent by conjugating albumin with a NIR nonfluorescent dye (QC-1) and a visible spectrum fluorescent dye, a BODIPY derivative. The new hybrid tracer QC-1/BSA/BODIPY (QBB) had a low minimum detectable concentration (2.5μM), a steep linear range (2.4–54.4 μM; slope 3.39 E -5), and high photostability. Tracer signal was measured in vivo using PAI to quantify its drainage from eye to the neck and its localization in the neck lymph node was validated with postmortem fluorescence imaging.

使用新型造影剂的体内近红外（NIR）光声成像（PAI）研究通常需要通过验证荧光成像。NIR染料与蛋白质的生物缀合是获得用于特定生物医学应用的造影剂的多功能平台。与大多数荧光NIR染料相比，具有较高光稳定性的非荧光NIR染料具有定量PAI的优势。但是，它们不提供荧光成像所需的荧光信号。在这里，我们通过将白蛋白与NIR非荧光染料（QC-1）和可见光谱荧光染料BODIPY衍生物缀合，设计了一种混合型PA荧光造影剂。新的混合示踪剂QC-1 / BSA / BODIPY（QBB）的最低可检测浓度较低（2.5μM），线性范围较陡（2.4-54.4μM；斜率3.39 E -5），并且具有较高的光稳定性。体内测量示踪信号 使用死后荧光成像验证了使用PAI量化从眼睛到颈部的引流以及其在颈部淋巴结中的定位。