A sensitive and selective strategy to identify insulin fibrils remains a challenge for researchers in amyloid protein research. Thus, it is critical to detect, in vitro, the species generated during amyloid aggregation, particularly the fibrillar species. Here we demonstrate that the luminescent complex cis-[Ru(phen)₂(3,4Apy)₂]²⁺ (RuApy; phen = 1,10-phenanthroline; 3,4Apy = 3,4-diaminopyridine) is a rapid, low-cost alternative to in vitro detection of fibrillar insulin, using conventional optical techniques. The RuApy complex displays emission intensity enhancement at 655 nm when associated with insulin, which enables imaging of the conformational changes of the protein's self-aggregation. The complex shows high sensitivity to fibrillar insulin with a limit of detection of 0.85 μM and binding affinity of 12.40 ± 1.84 μM which is comparable to those of Thioflavin T and Congo red, with the advantage of minimizing background fluorescence, absorption of light by biomolecules, and light scattering from physiologic salts in the medium.

识别胰岛素原纤维的敏感和选择性策略仍然是淀粉样蛋白研究研究人员面临的挑战。因此，在体外检测淀粉样蛋白聚集过程中产生的物质，尤其是纤维状物质是至关重要的。在这里，我们证明了发光复合物cis- [Ru(phen) ₂ (3,4Apy) ₂ ] ²⁺（RuApy；phen = 1,10-菲咯啉；3,4Apy = 3,4-二氨基吡啶）是使用传统光学技术在体外检测纤维状胰岛素的一种快速、低成本的替代方法。当与胰岛素结合时，RuApy 复合物在 655 nm 处显示出发射强度增强，从而能够对蛋白质自聚集的构象变化进行成像。该复合物对纤维状胰岛素具有高灵敏度，检测限为 0.85 μM，结合亲和力为 12.40 ± 1.84 μM，与硫黄素 T 和刚果红相当，具有最小化背景荧光、生物分子吸收光的优势，以及介质中生理盐的光散射。