Magnetic-based SELEX(MB-SELEX)

May 8, 2024 • Bo Fu

Introduction

The use of magnetic beads in nucleic acid purification and separation had been established in molecular biology and biochemistry research prior to its application in SELEX. Magnet-based SELEX emerged as a response to the need for improved separation and manipulation of nucleic acid ligands during the SELEX process.

The key character of Magnet-based SELEX is the use of magnet functionalized with target molecules as a solid support matrix for capturing and isolating nucleic acid ligands. Bruno and his research team first introduced magnetic beads into the SELEX process in a study published in 1997 Magnetic bead-based SELEX offers several advantages over traditional SELEX methods, including enhanced separation efficiency, reduced nonspecific binding, and simplified manipulation of nucleic acid libraries. It has been successfully applied for the selection of aptamers against a variety of targets, including proteins, small molecules, and cells.

One of the primary challenges in developing Magnetic bead-based SELEX was optimizing the surface chemistry of magnetic beads to enable efficient immobilization of target molecules and nucleic acid libraries. Another difficulty was adapting the SELEX process to accommodate the use of magnetic beads as a solid support matrix without compromising the efficiency and specificity of the selection process. Initial studies demonstrated the feasibility of using magnetic beads for the immobilization of target molecules or nucleic acid library.

The development of Magnet-based SELEX was marked by the pioneering work of researchers who sought to integrate magnetic beads into the SELEX process. It has been successfully applied for the selection of aptamers against a variety of targets, including proteins, small molecules, and cells. The versatility and scalability of Magnet-based SELEX make it a valuable tool for the discovery of nucleic acid ligands with potential applications in therapeutics, diagnostics, and biotechnology. In a work published in 2012, Stoltenburg et al. reported a promising new approach based on MB-SELEX, Capture-SELEX, which is widely used in the development of aptamer that specifically targets small molecule compounds.

Process

Magnet-based SELEX retains the iterative process of SELEX, involving selection, partitioning, amplification, and enrichment of nucleic acid sequences. Magnet-based SELEX involves the incubation of a nucleic acid library with magnetic beads functionalized with target molecules. After incubation, the magnetic beads are collected using an external magnetic field, and unbound sequences are washed away. Bound sequences are then eluted from the magnetic beads, amplified, and subjected to subsequent rounds of selection to enrich for high-affinity ligands.

The main innovation of Capture-SELEX is that nucleic acid libraries, rather than targets, are fixed to magnetic beads before co-incubation. Capture-SELEX bypasses the problem that some targets cannot be fixed to the solid matrix and also avoids the enrichment of linker specific aptamer during the screening process.