Department of Chemistry, Birla Institute of Technology and Science-Pilani (Hyderabad Campus), Hyderabad-500078, India.
J Mater Chem B. 2024 Oct 23;12(41):10719-10735. doi: 10.1039/d4tb01229a.
The human serum albumin (HSA) level is a valuable indicator of an individual's health status. Therefore, its detection/estimation can be used to diagnose several diseases. In this work, we have developed a series of donor-π-acceptor probes, which were found to selectively detect HSA over BSA (bovine serum albumin). Among these probes, A4, which bears the trifluoroacetyl group, showed the highest selectivity for HSA, with limits of detection and quantification being 1.36 nM and 2.59 nM, respectively. CD spectroscopy of the HSA-A4 ensemble indicated an increase in the α-helicity of the protein, while the displacement assays revealed the localization of the probe in the hemin site of HSA. The probe works on the principle of excited state intramolecular charge transfer (ICT). Its selectivity was also validated computationally. Docking experiments confirmed the preference of the probe for the hemin binding IB site of HSA, as observed from the fluorescence displacement assay results, and a comparison of docking scores demonstrated the greater preference of A4 for HSA compared to BSA. Computational experiments also showed a change in preference for HSA amino acid residues exhibited by the excited state of probe A4 (Tyr161, Met123, Pro118, and Leu115) when compared to its ground state (Arg186 and His146). Hydrophobic interactions dominated the excited state protein-probe ensemble, whereas there was significant involvement of the water bridges along with the hydrophobic interactions in the ground state ensemble. Probe A4 was also assessed for its practical utility and found to successfully sense HSA in urine at extremely low concentrations. Moreover, the A4-HSA ensemble was employed for hemin sensing with a detection limit of 0.23 μM.
人血清白蛋白（HSA）水平是个体健康状况的一个有价值的指标。因此，它的检测/估计可以用于诊断几种疾病。在这项工作中，我们开发了一系列供体-π-受体探针，发现它们可以选择性地检测 HSA 而不是 BSA（牛血清白蛋白）。在这些探针中，带有三氟乙酰基的 A4 对 HSA 表现出最高的选择性，检测限和定量限分别为 1.36 nM 和 2.59 nM。HSA-A4 配合物的 CD 光谱表明蛋白质的α-螺旋性增加，而取代实验表明探针在 HSA 的血红素部位定位。探针基于激发态分子内电荷转移（ICT）原理工作。其选择性也通过计算得到了验证。对接实验证实了探针对 HSA 血红素结合 IB 位的偏好，这与荧光取代实验结果一致，并且对接得分的比较表明 A4 对 HSA 的偏好大于 BSA。计算实验还表明，与探针 A4 的基态（Arg186 和 His146）相比，其激发态对 HSA 氨基酸残基的偏好发生了变化（Tyr161、Met123、Pro118 和 Leu115）。在激发态蛋白质-探针配合物中，疏水相互作用占主导地位，而在基态配合物中，除了疏水相互作用外，还存在大量的水桥相互作用。探针 A4 还被评估了其实际用途，并发现它可以在极低浓度下成功地在尿液中检测到 HSA。此外，A4-HSA 配合物还用于血红素检测，检测限为 0.23 μM。
