Concept, characteristics and preparation method of magnetic biopolymer microspheres

The magnetic biopolymer microsphere material is a widely used carrier for organic solid phase synthesis and biomolecule immobilization. Immobilized biomolecules are commonly used as ligands for affinity separation analysis in biomedical and bioengineering research and practice, and as catalysts or drugs for biological reactions. Due to its magnetic properties, magnetic polymer microspheres can be easily separated by the action of an external magnetic field, and can impart a variety of reactive functional groups on the surface by copolymerization. It has become an important direction for functional polymer research.

The concept of magnetic biopolymer microspheres

In the past 20 years, the research of magnetic polymer microspheres has been very active, and has evolved from the simplest polymer-wrapped magnetic materials to various types of composition. The magnetic polymer microspheres are composed of two parts: a guiding core layer (magnetic core) and an affinity and biocompatibility shell layer. The structure generally has four types, namely: core-shell type and shell-core type, shell-core-shell type and mosaic type.

Characteristics of magnetic biopolymer microspheres

(1) Surface effect and volume effect: the specific surface area effect. With the refinement of the microspheres, when the particle size reaches the micron level or even the nanometer level, the specific surface surges, the microsphere functional group density and the selective adsorption capacity become larger, the time for reaching the adsorption equilibrium is greatly shortened, and the stability of the particles is greatly improved.

(2) Magnetic effect: Magnetically, the biopolymer microspheres can be easily separated and magnetically guided by an external magnetic field. When the magnetic ferroferric oxide crystal has a diameter of less than 30 nm, it has superparamagnetism, that is, it has strong magnetic properties in a magnetic field, and the magnetic properties quickly disappear without a magnetic field, so that the biopolymer microspheres can be not permanently magnetized in a magnetic field.

(3) Biocompatibility: An important aspect of the application of magnetic microspheres in bioengineering, especially biomedical engineering, is to have biocompatibility. Most biopolymers such as polysaccharides and proteins have good biocompatibility.

(4) Functional base characteristics: Biopolymers have a variety of reactive functional groups, such as -OH, -COOH, -NH₂, which can be attached to biologically active substances.

Method for preparing magnetic biopolymer microspheres

The chemical conversion method refers to synthesizing uniform porous organic polymer microspheres, and the microspheres contain functional groups such as -Cl, -CHO, -NO₂, -COOH, -SO₃H, etc., uniformly embedded in the surface and pores of the microspheres, and then the synthesized porous polymer microspheres are immersed in a certain concentration of Fe²⁺ and Fe³⁺ ion mixture, so that the polymer microspheres swell and penetrate in the iron salt solution, and then raise the pH value to obtain iron hydroxide. Finally, the material is heated to a suitable temperature to obtain magnetic polymer microspheres containing Fe₃O₄ particles. The method has the advantages compared with the above method: the prepared magnetic polymer microspheres have good monodispersity; and all magnetic polymer microspheres have consistent magnetic responsiveness under magnetic field: various preparations can be prepared dense or porous magnetic polymer microsphere having a particle size, and a high magnetic content microsphere having a magnetic content of more than 30% can be prepared.

Related links: Carboxyl magnetic microspheres

Edited by Suzhou Yacoo Science Co., Ltd.