Detection and identification of proteins are typically achieved by analyzing protein size, charge, mobility and binding to antibodies, which are critical for biomedical research and disease diagnosis and treatment. Despite the importance, measuring these quantities with one technology and at the single-molecule level has not been possible. Here we tether a protein to a surface with a flexible polymer, drive it into oscillation with an electric field, and image the oscillation with a near field optical imaging method, from which we determine the size, charge, and mobility of the protein. We also measure antibody binding and conformation changes in the protein. The work demonstrates a capability for comprehensive protein analysis and precision protein biomarker detection at the single molecule level.

蛋白质的检测和鉴定通常通过分析蛋白质的大小、电荷、迁移率和与抗体的结合来实现，这对于生物医学研究和疾病诊断和治疗至关重要。尽管很重要，但用一种技术在单分子水平上测量这些数量是不可能的。在这里，我们用柔性聚合物将蛋白质拴在一个表面上，用电场驱动它振荡，并用近场光学成像方法对振荡进行成像，从中我们确定蛋白质的大小、电荷和迁移率。我们还测量了蛋白质中的抗体结合和构象变化。该工作展示了在单分子水平进行全面蛋白质分析和精确蛋白质生物标志物检测的能力。