Characterization of Nanoparticle Adsorption on Polydimethylsiloxane-Based Microchannels

Hirotada Hirama,Ryutaro Otahara,Masanori Hayase,Shinya Kano,Harutaka Mekaru

doi:10.3390/s21061978

Abstract

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.

Highlights

IntroductionNucleic acids [4] have been developed
Given the growing popularity of nanoparticles (NPs) (e.g., poly(lactide-co-glycolide)NPs, solid lipid NPs, and exosomes) as diagnosis and analysis tools for pharmaceutical [1]and medical [2] applications, several methods for the detection and analysis of viruses [3]and nucleic acids [4] have been developed
The adsorption of polystyrene NPs on the PDMS-based substrate was characterized by atomic force microscopy (AFM) imaging of the substrate that had been immersed in the corresponding NP dispersions (Figure 2)

Summary

Introduction

Nucleic acids [4] have been developed. A great deal of attention has been given to the study of exosomes, which contain proteins, lipids, and nucleic acids (including miRNAs) that are secreted by cells and are present in various body fluids such as urine [5], saliva [6], and blood [7]; exosomes mediate communication between cells [8]. Given that the physical properties of NPs depend on their size and surface charge [12,13], size- and charge-driven NP handling techniques are crucial for the detection and analysis of biomarkers such as exosomes, viral particles, and nucleic acids. As microchannel-based microfluidic devices allow for nano-, pico-, and femtoliter-scale manipulations [14] and are superior to rapid sample processing and analysis [15], microscale sample analysis [16], and high-throughput analysis [17], various NP separation and concentration techniques have been developed to increase NP detection sensitivity [13,18]

Methods

Results

Conclusion