Nanoparticles (NPs) have been widely applied in fields as diverse as energy conversion, photovoltaics, environment remediation, and human health. However, the adsorption and trapping of NPs interfaces is still poorly understood, and few studies have characterized the kinetics quantitatively. In many applications, such as drug delivery, understanding NP interactions at an interface is essential to determine and control adsorption onto targeted areas. Therapeutic NPs are especially interesting because their structures involve somewhat hydrophilic surface coronas, to prevent protein adsorption, and much more hydrophobic core phases. We initiated this study after observing aggregates of nanoparticles in dispersions where there had been exposure of the dispersion to air interfaces. Here, we investigate the evolution of NP attachment and structural evolution at the air–liquid interface over time scales from 100 ms to 10s of seconds. We document three distinct stages in NP adsorption. In addition to an early stage of free diffusion and a later one with steric adsorption barriers, we find a hitherto unrealized region where the interfacial energy changes due to surface “denaturation” or restructuring of the NPs at the interface. We adopt a quantitative model to calculate the diffusion coefficient, adsorption rate and barrier, and extent of NP hydrophobic core exposure at different stages. Our results deepen the fundamental understanding of the adsorption of structured NPs at an interface.

中文翻译：

---

界面处结构化聚合物纳米粒子的吸附和变性

纳米粒子（NPs）已广泛应用于能源转换，光伏，环境修复和人类健康等领域。然而，对NPs界面的吸附和捕集仍然知之甚少，很少有研究对动力学进行定量表征。在许多应用中，例如药物输送，了解界面处的NP相互作用对于确定和控制目标区域的吸附至关重要。治疗性NP尤其令人感兴趣，因为它们的结构在某种程度上涉及亲水性表面电晕，以防止蛋白质吸附，并具有更多的疏水核心相。我们在观察分散体中暴露于空气界面的分散体中的纳米颗粒聚集体之后，开始了这项研究。这里，我们研究了从100毫秒到10秒的时间范围内，气液界面上NP附着的演化和结构演化。我们记录了NP吸附的三个不同阶段。除了早期的自由扩散和后期的具有空间吸附壁垒之外，我们还发现了迄今为止尚未实现的区域，该区域的界面能由于界面的“变性”或NP的重组而改变了界面能。我们采用定量模型来计算不同阶段NP疏水性核的扩散系数，吸附率和势垒以及暴露程度。我们的结果加深​​了对结构化NP在界面上吸附的基本理解。除了早期的自由扩散和后期的具有空间吸附壁垒之外，我们还发现了迄今为止尚未实现的区域，该区域的界面能由于界面的“变性”或NP的重组而改变了界面能。我们采用定量模型来计算不同阶段NP疏水性核的扩散系数，吸附率和势垒以及暴露程度。我们的结果加深​​了对结构化NP在界面上吸附的基本理解。除了早期的自由扩散和后期的具有空间吸附壁垒之外，我们还发现了迄今为止尚未实现的区域，在该区域中，界面能由于表面的“变性”或NP的重组而发生了变化。我们采用定量模型来计算不同阶段NP疏水性核的扩散系数，吸附率和势垒以及暴露程度。我们的结果加深​​了对结构化NP在界面上吸附的基本理解。NP疏水核在不同阶段的暴露程度。我们的结果加深​​了对结构化NP在界面上吸附的基本理解。NP疏水核在不同阶段的暴露程度。我们的结果加深​​了对结构化NP在界面上吸附的基本理解。