Block Stephan, Fast Björn Johansson, Lundgren Anders, Zhdanov Vladimir P, Höök Fredrik
Department of Physics, Division of Biological Physics, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.
Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Vienna 1190, Austria.
Nat Commun. 2016 Sep 23;7:12956. doi: 10.1038/ncomms12956.
Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging. Optical microscopy allows precise determination of fluorescence/scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. Here, we show that by attaching BNPs to a supported lipid bilayer, subjecting them to hydrodynamic flows and tracking their motion via surface-sensitive optical imaging enable determination of their diffusion coefficients and flow-induced drifts, from which accurate quantification of both BNP size and emission intensity can be made. For vesicles, the accuracy of this approach is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity for radii down to 15 nm.
生物纳米颗粒（BNPs）因其在各种生物过程中的关键作用以及作为生物标志物的用途而备受关注。BNP的大小和组成对其功能起决定性作用，但同时高精度地确定这两个特性仍然具有挑战性。光学显微镜可以精确测定荧光/散射强度，但无法确定单个BNP的大小。后者通过跟踪它们在大量物质中的随机运动能得到更好的测定，但用于跟踪这种运动的有限照明体积阻碍了可靠的强度测定。在这里，我们表明，通过将BNP附着到支撑脂质双层上，使其受到流体动力流作用，并通过表面敏感光学成像跟踪它们的运动，可以确定它们的扩散系数和流动诱导漂移，由此可以对BNP的大小和发射强度进行准确量化。对于囊泡，通过解析其荧光强度对低至15纳米半径的预期半径平方依赖性，证明了该方法的准确性。
