中央研究院 原子與分子科學研究所

Single-molecule tracking is a powerful method to study molecular dynamics in living systems including biological membranes. High-resolution single-molecule tracking requires a bright and stable signal, which has typically been facilitated by nanoparticles due to their superb optical properties. However, there are concerns about using a nanoparticle to label a single molecule because of its relatively large size and the possibility of cross-linking multiple target molecules, both of which could affect the original molecular dynamics. In this work, using various labeling schemes, we investigate the effects using nanoparticles to measure the diffusion of single-membrane molecules. We demonstrate a simple and robust strategy for the monovalent and oriented labeling of a single lipid molecule with a AuNP by using naturally dimeric rhizavidin (rAv) as a bridge, thus connecting the biotinylated nanoparticle surface and biotinylated target molecule. The rAv–AuNP conjugate shows fast and free diffusion in supported lipid bilayers (2–3 μm²/s for rAv–AuNP sizes of 10–40 nm), which is comparable to the diffusion of dye-labeled lipids, indicating that the adverse size and cross-linking effects are successfully avoided. Our work shows that the measured diffusion of the membrane molecule is highly sensitive to the molecular design of the cross-linker for labeling. The demonstrated approach of monovalent and oriented AuNP labeling provides the opportunity to study single-molecule membrane dynamics at much higher spatiotemporal resolutions and, most importantly, without labeling artifacts.

This work is selected as 2019 Significant Research Achievement of Academia Sinica and reported by ACS Nano Perspective (Yanqi Yu, Miao Li, Yan Yu. Tracking Single Molecules in Biomembranes: Is Seeing Always Believing?. ACS Nano 2019, 13 (10) , 10860-10868.)

link: 相關連結