Human Augmentation Research Center, National Institute of Advanced Industrial Science and Technology, Chiba 277-0882, Japan.
Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan.
Sensors (Basel). 2021 Mar 11;21(6):1978. doi: 10.3390/s21061978.
Nanoparticles (NPs) are used in various medicinal applications. Exosomes, bio-derived NPs, are promising biomarkers obtained through separation and concentration from body fluids. Polydimethylsiloxane (PDMS)-based microchannels are well-suited for precise handling of NPs, offering benefits such as high gas permeability and low cytotoxicity. However, the large specific surface area of NPs may result in nonspecific adsorption on the device substrate and thus cause sample loss. Therefore, an understanding of NP adsorption on microchannels is important for the operation of microfluidic devices used for NP handling. Herein, we characterized NP adsorption on PDMS-based substrates and microchannels by atomic force microscopy to correlate NP adsorptivity with the electrostatic interactions associated with NP and dispersion medium properties. When polystyrene NP dispersions were introduced into PDMS-based microchannels at a constant flow rate, the number of adsorbed NPs decreased with decreasing NP and microchannel zeta potentials (i.e., with increasing pH), which suggested that the electrostatic interaction between the microchannel and NPs enhanced their repulsion. When exosome dispersions were introduced into PDMS-based microchannels with different wettabilities at constant flow rates, exosome adsorption was dominated by electrostatic interactions. The findings obtained should facilitate the preconcentration, separation, and sensing of NPs by PDMS-based microfluidic devices.
纳米粒子（NPs）在各种医学应用中得到了广泛的应用。外泌体是一种生物衍生的 NPs，通过从体液中分离和浓缩获得，具有很大的应用潜力，可作为生物标志物。基于聚二甲基硅氧烷（PDMS）的微通道非常适合精确处理 NPs，具有高气透性和低细胞毒性等优点。然而，NPs 的大比表面积可能导致其在器件基底上发生非特异性吸附，从而导致样品损失。因此，了解 NPs 在微通道上的吸附情况对于用于处理 NPs 的微流控设备的操作非常重要。在此，我们通过原子力显微镜对 PDMS 基基底和微通道上的 NP 吸附进行了表征，将 NP 的吸附性与 NP 和分散介质特性相关的静电相互作用联系起来。当将聚苯乙烯 NP 分散体以恒定流速引入 PDMS 基微通道时，随着 NP 和微通道 ζ 电位（即 pH 值降低）的降低，吸附的 NP 数量减少，这表明微通道与 NPs 之间的静电相互作用增强了它们的排斥作用。当具有不同润湿性的外泌体分散体以恒定流速引入 PDMS 基微通道时，外泌体的吸附主要由静电相互作用决定。这些发现应该有助于 PDMS 基微流控设备对 NPs 的预浓缩、分离和传感。
