Modeling protein release from crosslinked gelatin-coated orthopedic biomaterials

Release of a model protein lysozyme from glutaraldehyde crosslinked gelatin layers applied on Co-Cr-Mo alloy samples was described mathematically. The release exhibited three phases: (1) initial burst, (2) diffusion controlled release, and (3) degradation-controlled release. The initial burst amount, as a percentage of the loaded amount, was inversely proportional to glutaraldehyde crosslinking. In the diffusion-controlled phase, Fick´s law was used to calculate an effective diffusivity, dependent on glutaraldehyde percentage. In the degradation-controlled phase, the first order reaction rate for the dissolution of gelatin was scaled to approximate the release of lysozyme