Fig. 6.

Fluorescence lifetime can longitudinally monitor the change in autofluorescence of collagen gels treated by 0.2% GTA. Mean fluorescence lifetime recorded in (a) CH1, (b) CH2, and (c) CH3 plotted as a function of collagen hydrogel incubation time in solutions of 0.0% (control) and 0.2% GTA. The measurements were taken from $n=2\text{\hspace{0.17em}\hspace{0.17em}hydrogels}/\text{group}$ that were repeatedly imaged every 15 min for the duration of the 1-h cross-linking period. Error bars are $\pm 1$ standard deviation.