Effect of hydroxypropyl methylcellulose on collagen fibril formation in vitro.

Collagen and hydroxypropyl methylcellulose (HPMC) were mixed to obtain blends and the effect of HPMC on collagen self-assembly was studied. As deduced from atomic force microscopy (AFM), the amount of nuclei in collagen-HPMC solutions was changed with the addition of HPMC. Under physiological conditions, the kinetics curves of fibril formation showed that the turbidity of blends at 313 nm was higher than that of native collagen. More HPMC was involved in the hydrogel network for blends with higher HPMC/collagen. However, both the thermal stability and the storage moduli of hydrogels, which was evaluated by UV and rheological measurements respectively, reached the maximum just when HPMC/collagen=0.25. Furthermore, it was showed by AFM that denser fibrils with smaller diameter would be obtained as HPMC/collagen<0.25, while more addition of HPMC (HPMC/collagen>0.25) would bring about fibrils with larger diameter. However, HPMC did not significantly affect the characteristic D-periods of the fibrils for all blends.