A Novel Electrokinetic Membrane System for Efficient Nanoparticle Preconcentration and Separation

Efficient preconcentration and separation of colloidal nanoparticles are pivotal for various biomedical and pharmaceutical applications, especially as target substances decrease in size. In this work, we introduce an innovative electric field-assisted membrane system that integrates oversized-pore membranes with an electrokinetic particle retention mechanism. By generating the electric field directly from a Ti/Au-coated PTFE membrane, nanoparticles even smaller than the pores are electrokinetically isolated and retained with over 99% separation efficiency and a 1.7-fold concentration increase. Compared to conventional membrane processes, our approach significantly reduces transmembrane pressure and particle adsorption, providing advantages such as low driving pressure and enhanced particle recovery. Comprehensive experimental and theoretical analyses reveal that this method optimally balances drag and electrokinetic forces on the nanoparticles, thus improving its performance. This innovative technique offers an energy-efficient and high-yield tool for biomolecule purification and enrichment, with potential applications in point-of-care diagnostics, highly sensitive biochemical detection, and biomanufacturing.