Albert C. Aragonès1
University of Barcelona1
Molecular trapping approaches<sup>[1]</sup> that rely on the electrical detection of single-molecule (SM) junctions<sup>[2,3]</sup> often face a significant challenge of short lifetimes, typically ranging from tens to hundreds of milliseconds,<sup>[4]</sup> primarily due to thermally activated junction breaking.<sup>[5]</sup> The limited detection timescales hinder comprehensive fundamental studies, making the extension of detection times a crucial challenge in SM detection. Our plasmon-supported break-junction (PBJ) technique<sup>[6]</sup> addresses this issue by significantly increasing the lifetime of SM junctions while preserving the native structure of the target molecule. Remarkably, the optical stabilizing force exerted by the nearfield gradient in PBJ enhances the stability of SM junctions, eliminating the need for chemical modifications of the target molecule or the electrode.<br/>In the first part, we will explore how the nearfield manipulation influences capture and release mechanisms.<sup>[7]</sup> As the field strength increases, the rate constant of capture kinetics rises while the release kinetics decrease, favouring the capture state over the release state. Consequently, the SM capture state becomes more likely and more stable than the release state above a specific nearfield strength threshold.<br/>In the second part, we will delve into how the PBJ trapping technique can be further enhanced for biomolecular contacts<sup>[8]</sup> through the manipulation of two physical features: (i) the optical resonance of the target molecule and (ii) the energy of the localized surface plasmon resonance in the nanogap. By leveraging these factors, we can extend the effectiveness of PBJ trapping in capturing and biomolecules.<br/><br/><br/>[1] C. S. Quintans, D. Andrienko, K. F. Domke, D. Aravena, S. Koo, I. Díez-Pérez, A. C. Aragonès, <i>Appl. Sci.</i> <b>2021</b>, <i>11</i>, 3317.<br/>[2] B. Xu, N. J. Tao, <i>Science</i> <b>2003</b>, <i>301</i>, 1221–3.<br/>[3] W. Haiss, R. J. Nichols, H. van Zalinge, S. J. Higgins, D. Bethell, D. J. Schiffrin, <i>Phys. Chem. Chem. Phys.</i> <b>2004</b>, <i>6</i>, 4330–4337.<br/>[4] A. C. Aragonès, et al, <i>Nature</i> <b>2016</b>, <i>531</i>, 88–91.<br/>[5] E. Evans, <i>Annu. Rev. Biophys. Biomol. Struct.</i> <b>2001</b>, <i>30</i>, 105–128.<br/>[6] A. C. Aragonès, K. F. Domke, <i>Cell Rep. Phys. Sci.</i> <b>2021</b>, <i>2</i>, 100389.<br/>[7] K. F. Domke, A. C. Aragonès, <i>Nanoscale</i> <b>2022</b>, DOI 10.1039/D2NR05448E.<br/>[8] A. C. Aragonès, K. F. Domke, <i>J. Mater. Chem. C</i> <b>2021</b>, <i>9</i>, 11698–11706.