Mechanical and thermal properties of gelatin films at different degrees of glutaraldehyde crosslinking

The mechanical, thermal, swelling and release properties of glutaraldehyde (GTA) crosslinked gelatin films have been investigated in order to verify the influence of GTA concn. on the stability of the films. Air-dried films were submitted to treatment with GTA solns. at concns. ranging from 0.05 to 2.5 wt%. At the smallest GTA concn., the crosslinking degree, detd. by trinitrobenzensulfonic acid assay, amts. to about 60% and increases up to values near 100%, obtained with GTA concns. ³1 wt%. Simultaneously, the deformability of the films decreases, whereas the stress at break, sb, and the Young's modulus, E, increase. A crosslinking degree of about 85%, obtained using 0.25% GTA, is enough to prevent gelatin release in buffer soln. and to provoke a significant redn. of the swelling in physiol. soln. Furthermore, crosslinking greatly affects the thermal stability of the samples, as indicated by the results of differential scanning calorimetry (d.s.c.) investigation carried out on wet and air-dried films. The data suggest that the use of GTA at low concn., which is desiderable to prevent toxicity, allows to modulate the physico-chem. properties of gelatin films, in order to obtain stable materials with a wide range of possible biomedical applications.