Magnetic modulation of release of macromolecules from polymers.

Sustained-release systems were made by incorporating bovine serum albumin and magnetic steel beads in an ethylene-vinyl acetate copolymer matrix. When exposed to aqueous medium, the polymer matrix released the albumin slowly and continuously. Application of an oscillating magnetic field increased the release rate by as much as 100%. Intervals of 6-hr periods of magnetic exposure and nonexposure were alternated over a 5-day period, resulting in corresponding increases and decreases in release and establishing a pattern of modulated sustained release.