Figure 6

Osteogenic differentiation of osteoblasts on different substrates: (a) ALP activity after incubation for 4, 7, 14, and 21 days; (b) Extracellular calcium production after incubation for 4, 7, 14, and 21 days (# means P < 0.05, compared with glass groups; * means P < 0.05, compared with PDLLA groups; Δ means P < 0.05, compared with P-PUUs groups).