Theoretical Basis for Refractive Index Changes Resulting from Solution Phase Molecular Interaction.

IF 2.8 2区 化学 Q3 CHEMISTRY, PHYSICAL
The Journal of Physical Chemistry B Pub Date : 2025-04-03 Epub Date: 2025-03-25 DOI:10.1021/acs.jpcb.4c07563
Michael N Kammer, Amanda K Kussrow, Darryl J Bornhop
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引用次数: 0

Abstract

Refractive index (RI) is a fundamental optical property widely used to investigate the physical and chemical characteristics of materials. Here, we build on our previous work to refine the framework for RI sensing in solution-phase chemical and biochemical interactions. Starting from the Clausius-Mossotti relation, we present a first-principles derivation of a relationship for the RI signal resulting from chemical binding. We then demonstrate how the binding-induced conformational and hydration changes of interacting species relate to their estimated change in dielectric and thus the solution-phase change in refractive index (ΔRI). By varying the model parameters, such as solvation shell size and polarizability, we investigate the RI changes for two interactions: Ca2+ with the protein Recoverin and benzenesulfonamide with carbonic anhydrase 2 (CAII). These examples show that our theory predicts that even for small changes in binding-induced polarizability (relative to previous literature values), a quantifiable RI change is produced within the detectable range of RI detectors operating at ca. 10-6 RIU. Empirical observations confirm our theoretical predictions. Surprisingly, theory and experiment yield a decrease in ΔRI for the benzenesulfonamide-CAII interaction. We attribute this observation to shielding of charged residues and water molecule displacement during the binding event. Our approach is generalized, enabling it to be extended to other binding systems, as well as those undergoing nonbinding conformational changes, and facilitates the exploration of diverse biological and chemical processes by solution-phase RI sensing.

液相分子相互作用引起折射率变化的理论基础。
折射率(RI)是一种基本的光学性质,广泛用于研究材料的物理和化学特性。在此,我们以之前的工作为基础,完善了溶液相化学和生化相互作用中RI传感的框架。从Clausius-Mossotti关系出发,我们提出了由化学结合引起的RI信号关系的第一性原理推导。然后,我们展示了相互作用物质的结合诱导的构象和水化变化如何与它们的介电估计变化以及因此的折射率的溶液相变化相关(ΔRI)。通过改变模型参数,如溶剂化壳大小和极化率,我们研究了两种相互作用的RI变化:Ca2+与蛋白质恢复蛋白和苯磺酰胺与碳酸酐酶2 (CAII)。这些例子表明,我们的理论预测,即使对于结合诱导极化率的微小变化(相对于先前的文献值),在大约10-6 RIU的RI检测器的可检测范围内,也会产生可量化的RI变化。经验观察证实了我们的理论预测。令人惊讶的是,理论和实验得出了苯磺酰胺- cai相互作用ΔRI的减少。我们将这一观察结果归因于在结合过程中带电残基的屏蔽和水分子的位移。我们的方法是广义的,使其能够扩展到其他结合系统,以及那些经历非结合构象变化的系统,并促进了通过溶液相RI传感探索各种生物和化学过程。
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来源期刊
CiteScore
5.80
自引率
9.10%
发文量
965
审稿时长
1.6 months
期刊介绍: An essential criterion for acceptance of research articles in the journal is that they provide new physical insight. Please refer to the New Physical Insights virtual issue on what constitutes new physical insight. Manuscripts that are essentially reporting data or applications of data are, in general, not suitable for publication in JPC B.
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