Figure 2. Soft PIC hydrogels enhance organoid expansion.

Mechanical properties of Matrigel and PIC hydrogels measured at constant frequency (1 rad s⁻¹) and strain (1%). a) Time trace of storage modulus G′ showing hydrogel gelation with the temperature raising from 4 to 37 °C (+7 °C min⁻¹) and holding at 37 °C. For all conditions, the starting modulus at time = 0 min were much lower because all the samples were liquid at 4 °C; the modulus almost reached plateau at time = 6 min when the temperature was held at 37 °C (N = 3). b) Stiffness of hydrogels showing the storage modulus G′ of Matrigel and PIC hydrogels after 10 min incubation at 37 °C (N = 3). c) Time trace of storage modulus G′ and loss modulus G″ of Matrigel and PIC-LEC hydrogels through a heating and cooling cycle. At time = 0 min, G′ and G″ were close to each other in all three conditions showing a liquid state; at time = 5 min, G′ reached a peak higher than G″ after heating from 4 to 37 °C (+7 °C min⁻¹); during time = 5–10 min, all gels remained plateaued when the temperature was held at 37 °C; after time = 15 min, both PIC hydrogels showed a sharp decrease of G′ when the cooling cycle started from 37 to 4 °C (-7 °C min⁻¹), and G′ of both PIC hydrogels dropped to less than 1 Pa after being held at 4 °C for 10 min. However, G′ of Matrigel was still higher than 50 Pa after cooling for 15 min (N = 2).