3.4 - Encapsulation of Magnetic Ultra-Fine Particles and Fixation of Antibodies and Enzymes

Abstract

This chapter attempts to encapsulate magnetic ultrafine particles (UFPs) in a polymer so that the ease of separation and manipulation by magnetic fields, and small particle size and large specific surface area could be used as the immobilization carriers for antibodies and enzymes. The method of encapsulation and the evaluation of encapsulated UFPs are discussed. Antibodies and enzymes were also immobilized on the encapsulated UFPs and these materials were evaluated as well. A two-step process was used for the encapsulation. The first step used a condensation reaction between the hydroxyl groups on the surface of the iron UFPs and a silane coupling agent (vinyltrimethoxysilane, VTS). In the second step, an encapsulating film was formed on each UFP by vinyl polymerization between the vinyl groups on the surface of the iron UFPs and various vinyl monomers. By copolymerizing with AA or HEMA, the surfaces of the encapsulated UFPs could be covered with aldehyde or hydroxyl groups, respectively. The electrostatic interactions become dominant following encapsulation, which enhances the stability of the dispersion. As carriers for bioreactors, superior dispersion is essential and the encapsulation is one method of promoting the stability of dispersions. To promote chemical bonding of antibodies and enzymes to UFPs, iron UFPs are encapsulated by using monomers containing an aldehyde group (acrylaldehyde).