Figure 2.
Silk fibroin thin films were engineered for solubility post-drying and for mechanical strength to withstand the manual demolding process. (A) Film casting parameters were evaluated using 70 kDa silk fibroin to determine the relationship between solubility and the film mass-to-surface-area ratio, as measured using a BCA protein quantification assay. (B) Silk fibroin molecular weight was examined as a further mechanism to control film solubility; 235 kDa, 169 kDa, 70 kDa, and 36 kDa material was characterized at various mass-to-surface-area ratios, achieved through combinations of solution casting volume and protein concentration. Light gray indicates that demolding a film was not possible; dark gray indicates films were not soluble upon reconstitution; gray indicates formulations were considered viable for further study in the film format. The ranges of mass-to-surface-area ratios for each outcome are provided in μg/mm2 for each fibroin molecular weight.