Collaborative Research: A Stacked Plasmonic Nanopore for Tether-Free Stretching and Label-Free Sensing of hSTf Dynamics and Complex Formation at Ultra-Low Concentrations

蛋白质结构的基本知识及其对刺激或其他分子的动态反应对许多应用都很重要，包括医学诊断和治疗。人类血清转铁蛋白（hSTf）是血液中重要的铁载体，具有重要的临床意义，本研究旨在建立一种高灵敏度的方法来研究人类血清转铁蛋白（hSTf）。该传感技术将允许从铁结合蛋白中区分游离hSTf蛋白，并从非常小的血液样本中评估铁缺乏或铁过载。这种传感器的成功开发也将使广泛的其他蛋白质和生物分子的分析成为可能，例如DNA。该项目结合了生物化学、纳米工程、光子学和电子工程，为跨学科研究培训提供了极好的机会。南卫理公会大学（Southern Methodist University）和德克萨斯大学阿灵顿分校（University of Texas at Arlington）通过各种项目向K-12学校推广的努力，有助于激励更多学生攻读科学、技术、工程和数学（STEM）学位。堆叠等离子体纳米传感器是基于自诱导反作用（SIBA）驱动的纳米孔电泳（SANE）传感概念。堆叠的纳米孔设计独特，可以实现1)控制捕获、释放和重新捕获蛋白质或底物结合的蛋白质复合物；2)生物分子的瞬时变形，这可以由热效应或光电技术的结合引起；3)研究它们的变形动力学。在堆叠纳米孔传感器中实现的SANE概念允许在散装溶液中低于平衡解离常数1000倍的浓度下研究蛋白质相互作用，使该技术具有超高灵敏度。本研究的一个重要目的是利用SANE传感器研究游离hstf蛋白和铁结合蛋白复合物的性质。为每个物种建立光学特征谱，以使混合溶液中结合的复合物能够选择性地通过未结合的蛋白质进入底层孔隙。它使用对称（VCapture = VRecapture），其次是不对称（VCapture≠VRecapture）电压条件，以方便研究与蛋白质-底物结合、蛋白质松弛时间以及电压诱导的蛋白质展开是否可逆相关的强度和动力学参数。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Fundamental knowledge of protein structures and their dynamic responses to stimuli or other molecules is important for many applications, including medical diagnosis and therapy. This research aims to develop a highly sensitive approach for studying the human serum transferrin protein (hSTf), which is a vital iron carrier in blood and of clinical importance. The sensing technique would allow differentiation of the free hSTf protein from the iron-bound protein and evaluation of iron deficiency or iron overload from very small blood samples. Successful development of this sensor would also enable profiling of a wide range of other proteins and biological molecules, e.g., DNA. This project offers excellent opportunities for interdisciplinary research training as it combines biochemistry, nanoengineering, photonics, and electrical engineering. The outreach efforts to K-12 schools through various programs at the Southern Methodist University and the University of Texas at Arlington help to inspire more students to pursue science, technology, engineering and mathematics (STEM) degrees.The stacked plasmonic nanosensor is based on the self-induced back-action (SIBA) actuated nanopore electrophoresis (SANE) sensing concept. The stacked nanopores are uniquely designed to enable 1) controlled trapping, releasing, and recapturing of proteins or the substrate-bound protein complexes, 2) transient deformation of the biological molecules, which can be induced by thermal effect or a combination of optical and electrical techniques, and 3) study of their deformation dynamics. The SANE concept implemented in the stacked nanopore sensor allows investigation of protein interactions at concentrations 1000-fold below the equilibrium dissociation constant in bulk solution, making this technique ultra-sensitive. An important aim of this research is the study of the properties of free-hSTf protein and the iron-bound protein complex using the SANE sensor. Optical signature profiles are established for each of the species to enable selective admission of bound complexes over unbound proteins in a mixed solution to the underlying pore. It uses symmetric (VCapture = VRecapture), followed by asymmetric (VCapture ≠ VRecapture) voltage conditions to facilitate the investigation of the strength and kinetic parameters associated with protein-substrate binding, protein relaxation times, and whether voltage-induced protein unfolding is reversible or not.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.