Impartment of uptake and release functions to colagens and its application to dentin adhesion

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The aim of this project was to establish the method of uptake and controlled release of guest molecules into/from host biopolymers, such as collagen that is rich in the living body. The possibility of the controlled in vivo and in situ release of some antibacterial agents or adhesive components from dentinal collagen was examined.First, model collagen was prepared by cross-linking gelatin using glutaraldehyde, under various conditions. The higher concentration of glutaraldehyde resulted in a larger specific surface area and a higher denaturation temperature, suggesting the more cross-linked structure. Methylene blue was lead into these materials and was released by the addition of ethanol or saline solution.Next, tendon collagen, skin collagen films and acetylcellulose films were chosen as host polymers and methylene blue, acridine orange and acriflavine as guest molecules. Aqueous ethanol was used as squeezer of polymer gels. The amount of uptake and release was measured systematically. More dyes were taken into acetylcellulose film than into collagen materials, while release efficiency was higher for the collagens. The release was regulated by the concentration of ethanol added.It was suggested that the controlled release in this study was mainly due to the osmotic pressure that caused the collapse of polymer gels. On the basis of this study, more advanced control will be realized, in which the volume phase transition phenomena caused by pH or temperature condition, or electrostatic/hydrophobic interactions between host and guest are considered.