Figure 2.
Characterization of the materials. (A) Normalized FTIR spectra of zein powder and zein film in the region of amide I. The attribution of the main conformational states of the protein are reported. (B) XRD patterns of zein powder, zein, zein + Gly, Z/P 10/0, Z/P 6/4, Z/P 0/10, PVP + Gly, and PVP samples. (C) DSC curves of the zein, zein + Gly, Z/P 10/0, Z/P 6/4, Z/P 0/10, PVP + Gly, and PVP samples in the range of temperatures between 8 and 200 °C. The glass-transition temperatures have been highlighted with black lines. (D) Photographs of the static water contact angle analysis for the Z/P 10/0, 8/2, 7/3, 6/4, 2/8, and 0/10 samples. (E) Photographs of zein, zein + Gly, Z/P 10/0, 8/2, 6/4, 5/5, 4/6, 2/8, and 0/10 samples after immersion for 24 h in seawater. (F) Swelling degree values for zein, zein + Gly, Z/P 10/0, 8/2, 6/4, 5/5, 4/6, and 2/8 samples after immersion for 24 h in seawater. (G) Results of the nanoindentation test for the Z/P 10/0, 8/2, 6/4, 5/5, 4/6, 2/8, and Parafilm samples after immersion for 24 h in seawater. (H) Stress–strain curves for the Z/P 10/0, 6/4, and 0/10 samples at 0 and 84% R.H. The insets show the following: on the right a zoom of the stress–strain curves for Z/P 10/0, 6/4, and 0/10 samples at 0 and 84% R.H in the strain range 0.0–0.5 mm/mm; on the left a representative photograph of a wrapped Z/P 6/4 strip. (I) Results of the ABTS scavenging assay for the zein, Z/P 10/0, 8/2, 6/4, 5/5, 4/6, 2/8, 0/10, and PVP samples. (J) Cumulative release of curcumin for the Z/P 10/0, 8/2, 6/4, 5/5, 4/6, 2/8, and 0/10 samples at 25 °C. (K) Comparison of the curcumin release from Z/P 6/4 at 25, 29, and 33 °C. (L) Biochemical oxygen consumption (mg O2/100 g material) as a function of time (days) for the zein, Z/P 6/4, Z/P 6/4 no curcumin, PVP, and cellulose samples.