Fischell Department of Bioengineering, University of Maryland, College Park, MD.
Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, MD.
Photochem Photobiol. 2022 Jul;98(4):736-747. doi: 10.1111/php.13638. Epub 2022 May 23.
The benefits of contrast-enhancing imaging probes have become apparent over the past decade. However, there is a gap in the literature when it comes to the assessment of the phototoxic potential of imaging probes and systems emitting visible and/or near-infrared radiation. The primary mechanism of fluorescent agent phototoxicity is thought to involve the production of reactive molecular species (RMS), yet little has been published on the best practices for safety evaluation of RMS production levels for clinical products. We have proposed methods involving a cell-free assay to quantify singlet oxygen [(SO) a known RMS] generation of imaging probes, and performed testing of Indocyanine Green (ICG), Proflavine, Methylene Blue, IR700 and IR800 at clinically relevant concentrations and radiant exposures. Results indicated that SO production from IR800 and ICG were more than two orders of magnitude below that of the known SO generator Rose Bengal. Methylene Blue and IR700 produced much higher SO levels than ICG and IR800. These results were in good agreement with data from the literature. While agents that exhibit spectral overlap with the assay may be more prone to errors, our tests for one of these agents (Proflavine) appeared robust. Overall, our results indicate that this methodology shows promise for assessing the phototoxic potential of fluorophores due to SO production.
在过去的十年中，对比增强成像探针的优势已经变得明显。然而，在评估发射可见光和/或近红外辐射的成像探针和系统的光毒性潜力方面，文献中存在空白。荧光剂光毒性的主要机制被认为涉及活性分子种类（RMS）的产生，但关于临床产品 RMS 产生水平的安全评估的最佳实践，发表的内容很少。我们提出了涉及无细胞测定的方法来量化成像探针的单线态氧 [(SO) 一种已知的 RMS] 的产生，并以临床相关浓度和辐射暴露对吲哚菁绿 (ICG)、吖啶橙、亚甲蓝、IR700 和 IR800 进行了测试。结果表明，IR800 和 ICG 的 SO 生成量比已知的 SO 生成剂 Rose Bengal 低两个数量级以上。亚甲蓝和 IR700 产生的 SO 水平比 ICG 和 IR800 高得多。这些结果与文献中的数据非常吻合。虽然与测定法具有光谱重叠的试剂可能更容易出错，但我们对其中一种试剂（吖啶橙）的测试似乎很可靠。总体而言，我们的结果表明，由于 SO 产生，该方法有希望用于评估荧光团的光毒性潜力。
