Homogeneous Protein Analysis by Magnetic Core–Shell Nanorod Probes

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• 作者：Stefan Schrittwieser ; Beatriz Pelaz ; Wolfgang J. Parak ; Sergio Lentijo-Mozo ; Katerina Soulantica ; Jan Dieckhoff ; Frank Ludwig ; Thomas Altantzis ; Sara Bals ; Joerg Schotter
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 13, 2016
• 年：2016
• 卷：8
• 期：14
• 页码：8893-8899
• 全文大小：369K
• 年卷期：0
• ISSN：1944-8252

文摘

Studying protein interactions is of vital importance both to fundamental biology research and to medical applications. Here, we report on the experimental proof of a universally applicable label-free homogeneous platform for rapid protein analysis. It is based on optically detecting changes in the rotational dynamics of magnetically agitated core–shell nanorods upon their specific interaction with proteins. By adjusting the excitation frequency, we are able to optimize the measurement signal for each analyte protein size. In addition, due to the locking of the optical signal to the magnetic excitation frequency, background signals are suppressed, thus allowing exclusive studies of processes at the nanoprobe surface only. We study target proteins (soluble domain of the human epidermal growth factor receptor 2 - sHER2) specifically binding to antibodies (trastuzumab) immobilized on the surface of our nanoprobes and demonstrate direct deduction of their respective sizes. Additionally, we examine the dependence of our measurement signal on the concentration of the analyte protein, and deduce a minimally detectable sHER2 concentration of 440 pM. For our homogeneous measurement platform, good dispersion stability of the applied nanoprobes under physiological conditions is of vital importance. To that end, we support our measurement data by theoretical modeling of the total particle–particle interaction energies. The successful implementation of our platform offers scope for applications in biomarker-based diagnostics as well as for answering basic biology questions.