In vitro adsorption and activity of enzymes on reaction layers of bioactive glass substrates.

The effects of physiological biomolecules, particularly proteins, on the reactivity of bioactive glasses is being heavily researched. However, the effects of bioactive glasses on the activity of proteins have received little attention. Activity of horseradish peroxidase (HRP) adsorbed to the silica gel and hydroxycarbonate apatite layers of 45S5 bioactive glass was investigated. Surface reactions were terminated after development of a silica gel layer by the addition of edta to the reaction solution, which completely inhibited calcium phosphate formation. Complete loss of HRP activity on the silica gel layer was found to occur within 21 h while a minimal amount of activity from HCA-adsorbed HRP persisted indefinitely. These results show that bioactive glasses may serve as "friendly hosts" for adsorbed proteins, such as biologically active growth factors. These active peptides then, in turn, may generate an increased cellular response in the surrounding tissue, thereby enhancing the biogenic response.