Fig. 2.

Sample fabrication and characterization: (a) Schematic illustration of sample preparation; (b) Surface morphologies observed by FE-SEM; (c–f) High-resolution C1s spectra acquired from (c) PEEK, (d) PEEK-ALN, (e) PEEK-PIII, and (f) PEEK-IL4; (g) XPS survey spectra; (h) Atomic percentages determined by XPS; (i) Static water contact angles (n = 4 per group); (j) In vitro release profile of IL-4 and ALN from PEEK-IL4 incubated in the PBS solution at 37 °C (n = 6 per group). The inset presents the release profile in first 7 days. *p < 0.05 compared to PEEK, ^#p < 0.05 compared to PEEK-ALN, and ^&p < 0.05 compared to PEEK-PIII.