Department of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, Patiala-147001, India.
J Mater Chem B. 2024 Sep 18;12(36):9037-9049. doi: 10.1039/d4tb00749b.
The present study provides insight into the differential response of a benzimidazole-malononitrile fluorescent "Turn-ON" probe on interaction with two structurally similar proteins, BSA and HSA. Compound 6 shows more sensitivity towards the two SAs, which is completely lost in the case of compound 7, synthesized by substitution on 6. The aggregates of compound 6 show absorption maxima at 385 nm and weak emission maxima at 565 nm. Compound 6 forms a new emission band at 475 nm on gradual addition of BSA (200 μM) along with a slight increase in the emission band at 565 nm. However, on addition of HSA (50 μM), a new band at 475 nm is formed. In contrast to BSA, in the case of HSA, 50% quenching is observed in the emission band of compound 6 at 565 nm. The new band formed on the interaction of 6 with BSA shows four-fold more enhancement compared to HSA. Furthermore, the mechanism of interaction of 6 with serum albumin has been investigated through lifetime-fluorescence analysis, site-selective drug experiments, dynamic light scattering, FE-SEM, FT-IR, Molecular docking studies and site marker drug displacement experiments reveal differential interactions of 6 towards the two structurally similar proteins. Aggregates of 6 with an average hydrodynamic size of 100-190 nm are disassembled on adding BSA and HSA, and the size of the serum albumin and 6 complex decreases to 10-20 nm, revealing the ligand's encapsulation in the serum albumin cavity. Practical applicability for the quantitative detection of HSA in human urine samples is also demonstrated. The high binding affinity, sensitivity, selectivity and differential response of probe 6 towards two serum albumins (HSA and BSA) and significant quantification of HSA in urine samples shows the potential ability of this probe in medical applications.
本研究深入了解了苯并咪唑-丙二腈荧光“开启”探针与两种结构相似的蛋白质（BSA 和 HSA）相互作用的差异响应。化合物 6 对两种磺胺类药物表现出更高的灵敏度，而通过在 6 上取代合成的化合物 7 则完全失去了这种灵敏度。化合物 6 的聚集物在 385nm 处显示出最大吸收峰，在 565nm 处显示出较弱的发射峰。当逐渐加入 BSA（200μM）时，化合物 6 形成一个新的发射带，在 475nm 处，同时在 565nm 处的发射带略有增加。然而，当加入 HSA（50μM）时，在 475nm 处形成一个新的带。与 BSA 不同，在 HSA 的情况下，在 565nm 处观察到化合物 6 的发射带发生了 50%的猝灭。6 与 BSA 相互作用形成的新带的强度比与 HSA 相互作用时提高了四倍。此外，通过寿命荧光分析、选择性药物实验、动态光散射、FE-SEM、FT-IR、分子对接研究和位点标记药物置换实验，研究了 6 与血清白蛋白的相互作用机制，这些实验表明 6 与两种结构相似的蛋白质具有不同的相互作用。6 的聚集物的平均水动力直径为 100-190nm，当加入 BSA 和 HSA 时会被分解，而血清白蛋白和 6 复合物的大小减小到 10-20nm，表明配体被包裹在血清白蛋白空腔中。还展示了用于定量检测人尿样中 HSA 的实际应用。探针 6 对两种血清白蛋白（HSA 和 BSA）的高结合亲和力、灵敏度、选择性和差异响应以及对尿样中 HSA 的显著定量表明了该探针在医学应用中的潜在能力。
