Fig 1.
Freezing-induced expansion of collagen fibril.
Average confinement of single collagen molecule in the fibril is modeled by considering an equilateral hexagonal unit cell for confinement based on a quasi-hexagonal packing state [44, 45]. Unit cell expands as intrafibrillar fluid freezes. dm is tropocollagen nominal diameter, d is confinement diameter, dc is the length of a side of the unit cell.
Fig 2.
(A) Representative MTDSC heating thermograms that show endothermic peaks of denaturation for F/T versus UF collagen in hydrogels and molecular solutions. Lines and shaded regions indicate the mean and standard deviation respectively. Denaturation temperature of collagen in (B) molecular solution and (C) hydrogel. ‘*’ indicates significant difference (p < 0.05).
Fig 3.
Effects of F/T conditions on post-thaw denaturation temperature.
‘*’ indicates significant difference (p < 0.05).
Fig 4.
Recovery of collagen post-thaw thermal stability by use of cryoprotectant, DMSO.
Fig 5.
Freezing-induced morphological changes in collagen hydrogels at network and fibril levels.
(A) Representative SEM images. Scale bars are 5 μm and 500 nm for top and bottom panels respectively. (B) Hydrogel fibril diameter distributions.
Fig 6.
Prediction of denaturation temperature decrease upon F/T by computational modeling.
(A) The change in denaturation temperature upon hypothetical expansion of a tightly packed fibril (minimum porosity). (B) The amount of freezing-induced fibril expansion and change in denaturation temperature as a function of unfrozen fibril porosity.