Investigation of the mechanical properties of collagen fibrils under the influence of low power red laser irradiation

The low level red laser has been increasingly used for medical applications over the last decade. Despite the recorded positive effects of low level red laser in various medical treatments, the exact collagenred light interaction mechanism still remains unknown. Hence, in this paper, thin collagen films were irradiated using red low power laser in order to investigate the effects of red light on collagen nanoscale features and mechanical properties. The results demonstrated that the red light did not induce statistically significant changes on nanoscale collagen topography features. The topography of the alternating sequence of overlapping and gap regions (D-band periodicity) and the surface roughness were not affected. However, significant changes on the mechanical properties of the collagen fibrils were recorded. In particular, the red light induced major changes in the mechanical heterogeneity of the fibrils due to the D-band periodicity. The above results provide new information about the red light-collagen interaction mechanism and are a step forward towards to the clarification of the impact of red light on collagen nanoscale features.