ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels08860, Spain.
Nanophotonic Systems Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, Zurich8092, Switzerland.
ACS Nano. 2023 Jan 10;17(1):221-229. doi: 10.1021/acsnano.2c06883. Epub 2022 Dec 16.
Rapid and reliable characterization of heterogeneous nanoparticle suspensions is a key technology across the nanosciences. Although approaches exist for homogeneous samples, they are often unsuitable for polydisperse suspensions, as particles of different sizes and compositions can lead to indistinguishable signals at the detector. Here, we introduce holographic nanoparticle tracking analysis, holoNTA, as a straightforward methodology that decouples size and material refractive index contributions. HoloNTA is applicable to any heterogeneous nanoparticle sample and has the sensitivity to measure the intrinsic heterogeneity of the sample. Specifically, we combined high dynamic range k-space imaging with holographic 3D single-particle tracking. This strategy enables long-term tracking by extending the imaging volume and delivers precise and accurate estimates of both scattering amplitude and diffusion coefficient of individual nanoparticles, from which particle refractive index and hydrodynamic size are determined. We specifically demonstrate, by simulations and experiments, that irrespective of localization uncertainty and size, the sizing sensitivity is improved as our extended detection volume yields considerably longer particle trajectories than previously reported by comparable technologies. As validation, we measured both homogeneous and heterogeneous suspensions of nanoparticles in the 40-250 nm size range and further monitored protein corona formation, where we identified subtle differences between the nanoparticle-protein complexes derived from avidin, bovine serum albumin, and streptavidin. We foresee that our approach will find many applications of both fundamental and applied nature where routine quantification and sizing of nanoparticles are required.
快速可靠地对异质纳米颗粒悬浮液进行特征描述是整个纳米科学领域的一项关键技术。虽然针对均相样品存在一些方法，但它们通常不适合多分散悬浮液，因为不同大小和组成的颗粒在探测器处可能会产生无法区分的信号。在这里，我们引入全息纳米颗粒跟踪分析（holographic nanoparticle tracking analysis，holoNTA）作为一种简单的方法，该方法可以分离尺寸和材料折射率的贡献。holoNTA 适用于任何异质纳米颗粒样品，具有测量样品固有异质性的灵敏度。具体来说，我们将高动态范围 k 空间成像与全息 3D 单颗粒跟踪相结合。这种策略通过扩展成像体积来实现长期跟踪，并对单个纳米颗粒的散射幅度和扩散系数进行精确和准确的估计，从而确定颗粒的折射率和水动力尺寸。我们通过模拟和实验具体证明，无论定位不确定性和尺寸如何，由于我们的扩展检测体积产生的颗粒轨迹比以前报道的可比技术长得多，因此尺寸测量的灵敏度得到了提高。作为验证，我们测量了 40-250nm 尺寸范围内的同质和异质纳米颗粒悬浮液，并进一步监测了蛋白质冠形成，从中我们识别出了源自亲和素、牛血清白蛋白和链霉亲和素的纳米颗粒-蛋白质复合物之间的细微差异。我们预计，我们的方法将在需要常规定量和尺寸测量的基础研究和应用研究中得到广泛应用。
