Moreno-Chaparro Daniela, Moreno Nicolas, Usabiaga Florencio Balboa, Ellero Marco
Basque Center for Applied Mathematics, BCAM, Alameda de Mazarredo 14, Bilbao 48400, Spain.
J Chem Phys. 2023 Mar 14;158(10):104108. doi: 10.1063/5.0136833.
Functionalized nanoparticles (NPs) are complex objects present in a variety of systems ranging from synthetic grafted nanoparticles to viruses. The morphology and number of the decorating groups can vary widely between systems. Thus, the modeling of functionalized NPs typically considers simplified spherical objects as a first-order approximation. At the nanoscale label, complex hydrodynamic interactions are expected to emerge as the morphological features of the particles change, and they can be further amplified when the NPs are confined or near walls. Direct estimation of these variations can be inferred via diffusion coefficients of the NPs. However, the evaluation of the coefficients requires an improved representation of the NPs morphology to reproduce important features hidden by simplified spherical models. Here, we characterize the passive transport of free and confined functionalized nanoparticles using the Rigid Multi-Blob (RMB) method. The main advantage of RMB is its versatility to approximate the mobility of complex structures at the nanoscale with significant accuracy and reduced computational cost. In particular, we investigate the effect of functional groups' distribution, size, and morphology over nanoparticle translational and rotational diffusion. We identify that the presence of functional groups significantly affects the rotational diffusion of the nanoparticles; moreover, the morphology of the groups and number induce characteristic mobility reduction compared to non-functionalized nanoparticles. Confined NPs also evidenced important alterations in their diffusivity, with distinctive signatures in the off-diagonal contributions of the rotational diffusion. These results can be exploited in various applications, including biomedical, polymer nanocomposite fabrication, drug delivery, and imaging.
功能化纳米颗粒（NPs）是存在于从合成接枝纳米颗粒到病毒等各种系统中的复杂物体。不同系统中修饰基团的形态和数量差异很大。因此，功能化纳米颗粒的建模通常将简化的球形物体作为一阶近似。在纳米尺度上，随着颗粒形态特征的变化，预计会出现复杂的流体动力学相互作用，当纳米颗粒受限或靠近壁面时，这种相互作用会进一步放大。可以通过纳米颗粒的扩散系数直接推断这些变化。然而，系数的评估需要改进纳米颗粒形态的表示，以再现简化球形模型所隐藏的重要特征。在这里，我们使用刚性多团块（RMB）方法表征自由和受限功能化纳米颗粒的被动输运。RMB的主要优点是其通用性，能够以显著的精度和降低的计算成本近似纳米尺度上复杂结构的迁移率。特别是，我们研究了官能团的分布、大小和形态对纳米颗粒平移和旋转扩散的影响。我们发现官能团的存在显著影响纳米颗粒的旋转扩散；此外，与未功能化的纳米颗粒相比，官能团的形态和数量会导致特征性的迁移率降低。受限的纳米颗粒在扩散率方面也表现出重要变化，在旋转扩散的非对角贡献中有独特的特征。这些结果可用于各种应用，包括生物医学、聚合物纳米复合材料制造、药物递送和成像。
