Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States.
School of Electrical Computer and Energy Engineering, Arizona State University , Tempe, Arizona 85287, United States.
ACS Nano. 2018 Feb 27;12(2):2056-2064. doi: 10.1021/acsnano.8b00235. Epub 2018 Feb 6.
Measuring molecular binding to membrane proteins is critical for understanding cellular functions, validating biomarkers, and screening drugs. Despite the importance, developing such a capability has been a difficult challenge, especially for small-molecule binding to membrane proteins in their native cellular environment. Here we show that the binding of both large and small molecules to membrane proteins can be quantified on single cells by trapping single cells with a microfluidic device and detecting binding-induced cellular membrane deformation on the nanometer scale with label-free optical imaging. We develop a thermodynamic model to describe the binding-induced membrane deformation, validate the model by examining the dependence of membrane deformation on cell stiffness, membrane protein expression level, and binding affinity, and study four major types of membrane proteins, including glycoproteins, ion channels, G-protein coupled receptors, and tyrosine kinase receptors. The single-cell detection capability reveals the importance of local membrane environment on molecular binding and variability in the binding kinetics of different cell lines and heterogeneity of different cells within the same cell line.
测量分子与膜蛋白的结合对于理解细胞功能、验证生物标志物和筛选药物至关重要。尽管这很重要，但开发这种能力一直是一个艰巨的挑战，特别是对于小分子在其天然细胞环境中与膜蛋白的结合。在这里，我们展示了通过使用微流控设备捕获单个细胞，并使用无标记的光学成像在纳米尺度上检测结合诱导的细胞膜变形，可以在单细胞上定量测量大分子和小分子与膜蛋白的结合。我们开发了一个热力学模型来描述结合诱导的细胞膜变形，通过检查膜变形对细胞刚度、膜蛋白表达水平和结合亲和力的依赖性来验证该模型，并研究了四种主要类型的膜蛋白，包括糖蛋白、离子通道、G 蛋白偶联受体和酪氨酸激酶受体。单细胞检测能力揭示了局部膜环境对分子结合的重要性以及不同细胞系之间结合动力学的可变性和同一细胞系内不同细胞的异质性。
