We will review the kinetics, applications and efficacy of light-activated crosslink. The crosslink efficacy is influenced by multiple
factors including: the applied light intensity, exposure period and dose, the initial concentration profiles of photosensitizers (PS)
and oxygen, the quantum yield of the PS triplet state, the kinetic rate constants of PS (in type-I) and oxygen concentration (in type-
II). Lower light intensity (I0) and higher PS concentration (C0) provides higher efficacy, but also suffers more toxicity to the cells.
Higher light intensity (I0) may accelerate the crosslink but has lower efficacy (for the same dose). Therefore, optimal ratio of C0/
I0 is required for accelerated and safe crosslink. Safety issue also limits the maximum dose can be applied to the collagen, besides
the limitation of PS concentration. Three important issues are presented: improvement of the crosslink speed (via higher light
intensity) and efficacy of crosslink, and the role of photosensitizer (photo initiator) concentration.
Keywords: Lasers, Crosslink, Photodynamic Therapy, Tissue Engineering, Cancer Therapy, Ophthalmology