COL stimulation of the explants mainly resulted in the formation of globular collagen aggregates, however, collagen type 2 (COL2) fibrils were also observed (Figure , Supporting Information). The round structures may arise as a result of a high degree of collagen degradation caused by multiple cleaving sites of collagen by clostridial collagenase. The mechanism of such degradation has been investigated and reported by Watanabe-Nakayama et al. where similar globular structures were observed when collagen was subjected to type I collagenase cleavage. In samples treated with NP0, large meshes along with small round aggregates were observed, whereas less dense and irregular meshes were observed for NP5000, suggesting that these small NPs have the capacity to alter the assembly of the cleaved collagen.