Mass Transfer Characteristics of Glutaraldehyde-crosslinked and Epoxy-crosslinked Collagen Films
Collagen is a broadly used biomaterial and its mechanical strength can be enhanced by many crosslinking agents. Collagen matrices for drug delivery or tissue regeneration, however, are expected to have desired mass transfer characteristics. In this study, collagen films were crosslinked by two commonly used crossliking agents, namely glutaraldehyde (GTA) and epoxy. The mass transfer characteristics of the crosslinked collagen films were determined using theophylline (a hydrophilic drug) and benzocaine (a hydrophobic drug). The apparent diffusivities (Dapp) of theophylline and benzocaine in untreated collagen films were about 1×10-6 cm2/s and 3×10-7 cm2/s, respectively. The crosslinking treatments caused a decline in Dapp for both drugs. The Dapp values of theophylline and benzocaine in GTA-crosslinked and epoxy-crosslinked films were about one third of the Dapp values in the untreated films. In addition, swelling ratio of the GTA-crosslinked or epoxy-crosslinked films decreased by 50% as compared with untreated films. This study suggests that the decrease in the swelling ratio is due to the cross-linkages between collagen molecules, thereby increasing the mass transfer resistance and decreasing the Dapp values. Further, as compared to the hydrophilic drugs such as theophylline, the permeation of hydrophobic drugs such benzocaine in collagen films is relatively poor.