Collagen scaffolds were produced by a freeze-drying (lyophilization) method and chemically crosslinked using EDC/NHS at varying degrees (0%-100%). A contrast agent, phosphotungstic acid (PTA) was used to visualise fully hydrated collagen scaffolds in a physiologically relevant environment. The fully hydrated and stained samples were scanned using a μ-CT SkyScan 1172 (Bruker, Kontich, Belgium) at pixel size of 5 μm and their pore sizes were analysed using the CTAn software (Bruker).

The Microsoft Excel file called “uCT analysis results_Mean pore size and Volume shrinkage” contains the raw measurements of mean pore sizes and diameter of each collagen scaffold after various immersion treatments. This data was used to produce a part of Figure 2 and Figure 3. Furthermore, this file contains raw measurements of the volumes of 0%-XL scaffolds before and after immersion treatments. The average volume shrinkage in percentage was evaluated for each scaffold and the values were used to produce a part of Figure 3c and Figures 5a-g.

The other Microsoft Excel file called “uCT analysis results_Pore size distribution” contains the raw data after 3D analysis in the CTAn software for each collagen scaffold. This data was used to produce a part of Figure 2 and Figure 3.

Please see the main manuscript for more details, if needed.