Enhancing Immunoassays with Carboxylated Magnetic Beads: A Breakthrough in Diagnostics

What is A Carboxyl Magnetic Bead?

Carboxyl magnetic beads are a kind of biological magnetic beads, which generally have the characteristics of superparamagnetism, fast magnetic response, large specific surface area, monodisperse, colloid stability, and so on. The surface modification of carboxyl magnetic beads is rich in carboxyl groups, which can bind proteins, nucleic acids, and peptides to the surface of magnetic beads under the action of special chemical reagents. These magnetic beads are widely used in protein purification, immunoassay, molecular detection, NGS, cell separation, and other fields.

Applications of Carboxyl Magnetic Beads

• Chemiluminescent immunoassays

In chemiluminescent immunoassay (CLIA), magnetic beads are used as reaction carriers and coated with specific antigens or antibodies to capture target molecules. Proteins can bind to carboxyl-modified particles by adsorption. Adsorption is mediated by the hydrophobicity and ion interaction between protein and particle surface, and the adsorption occurs quickly. In addition to being adsorbed, proteins can also be covalently attached to the surface of carboxyl-modified particles. The carboxyl group on the particle is activated by water-soluble carbodiimide and reacts with the free amino group of the adsorbed protein to form amide bonds.

Absolute Mag™ Carboxyl Magnetic Particles for CLIA

CD Bioparticles has developed a wide range of carboxyl magnetic particles for CLIA, enabling customers to adapt to different systems and different targeting assays. They have the characteristics of fast response, rich carboxyl functional groups, monodispersity and submicron particle size, which can covalently conjugate peptides, proteins, oligonucleotides and other biological ligands to the surface of microspheres under the action of special chemical reagents (such as EDC, NHS). It is an important tool for medical and molecular biology research.

• Nucleic acid extraction

The system of extracting nucleic acid by carboxyl magnetic beads generally includes polyethylene glycol (PEG) and salt ions, in which PEG is an important factor affecting the recovery of nucleic acid. The principle is that in the presence of high concentrations of PEG and NaCl, the conformation of nucleic acid changes from linear to curly spherical, exposing a large number of negatively charged phosphate groups. The negatively charged phosphate group forms an ion bridge with the carboxyl group through Na+, so that the nucleic acid molecules are specifically adsorbed on the surface of the carboxyl magnetic beads. When the reaction buffer is removed, the addition of water molecules will quickly and fully hydrate the nucleic acid, eliminate the ion interaction between the three, and purify the nucleic acid adsorbed on the magnetic beads.

The longer the nucleic acid fragment is, the more negatively charged phosphate groups are exposed on the surface, and the magnetic beads will preferentially absorb large fragments, so the fragments above a specific size can be absorbed by adding a certain proportion of magnetic beads. Then the supernatant was removed and the nucleic acid on the magnetic beads was eluted to achieve nucleic acid purification. In NGS, it is often necessary to filter out specific-size DNA fragments from fragmented DNA libraries, so you can use magnetic beads for two rounds of adsorption to achieve size selection.

Absolute Mag™ Carboxyl Magnetic Particles for Nucleic Acid Extraction

CD Bioparticles provides DNA & RNA Magnetic Silica Particles and Extraction and Purification Kits for isolation of nucleic acids from plant tissues, whole blood, serum, plasma, buccal swabs, saliva, bacteria, plasmids, forensic samples and other body fluids.

• Protein Research

Proteome analysis based on mass spectrometry has always been a powerful technology for protein research, and the key step to determine sensitivity is the extraction of protein materials. With the aim of simplifying proteomics sample preparation, a Single-pot, solid-phase-enhanced sample-preparation (SP3) technology was developed, which is superior to the existing treatment methods in efficiency, scalability, speed, flux, and flexibility, and promotes hypersensitive analysis. SP3 is a magnetic bead-based method for fast, robust, and efficient processing of protein samples and is ideal for large or very small amounts of simple protein and complex protein mixtures.

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