Reconfigurable Magnetic Nanopore Platform for Selective Trapping

TL;DR

This paper presents a reconfigurable magnetic nanopore platform that enables selective trapping and controlled release of magnetic nanoparticles, enhancing nanoscale analysis capabilities.

Contribution

Introduction of a magnetic nanopore architecture with reversible switching between uniform and flux-closure states for active control of particle trapping.

Findings

Demonstrated magnetic trapping of fluorescent magnetic particles.

Achieved reversible switching of nanopore magnetic states with field pulses.

Enabled selective capture and release of biomolecules on demand.

Abstract

Solid-state nanopores offer a powerful platform for nanoscale analysis of individual analytes, including biomolecules and functionalized nanoparticles, by confining them within a precisely defined sensing region. However, their inherently passive operation restricts practical applications, as they cannot precisely control particle position or dynamics inside the pore. Here, we introduce magnetic nanopore architectures that integrate a ferromagnetic layer into the nanopore system. Acting as a magnetic discontinuity within an otherwise uniformly magnetized film, the nanopore generates localized stray magnetic fields that enable magnetic tweezing of magnetic nanoparticles, which can be functionalized with fluorescent biomolecules. Importantly, the nanopore geometry is designed to reversibly switch between a nearly uniform magnetization state and a magnetic flux-closure state through the application of short magnetic field pulses of controlled amplitude. This capability allows the magnetic tweezing effect to be selectively activated or deactivated, enabling controlled capture and release of tagged biomolecules on demand. As a proof of concept, we demonstrate the selective magnetic trapping of fluorescent magnetic particles. These findings pave the way for reconfigurable, on-chip magnetic nanopore platforms capable of selective trapping and high-throughput single-particle detection. KEYWORDS: Nanopores, magnetic tweezers, fluorescence microscopy, vortex state, active control, magnetic nanoparticles