Table 1 . Principal bands observed in Fourier transform infrared spectra and their relation with each hydrogel.
Figure legends .
Figure 1 . Scanning electron microscopy images of the four hydrogels. A-D : starch. E-H : starch-polyvinylalcohol.I-L : starch-chitosan. M-P : starch-chitosan-glutaraldehyde.
Figure 2 . Microscopic images and energy-dispersive X-ray spectroscopy analysis of starch-chitosan hydrogel. A : channel surface. B : small bead surface. C : big bead surface.
Figure 3 . Chitosan beads capsule-like structure observed by scanning electron microscopy. A : compact structure before continuous exposure to the electron beam. B : empty interior uncovered after exposure to the electron beam (red arrows).
Figure 4 . Fourier transform infrared spectra of the hydrogels.A : starch. B : starch-polyvinylalcohol. C : starch-chitosan. D : starch-chitosan-glutaraldehyde.
Figure 5 . Swelling rate of each hydrogel during 24 h.
Figure 6 . Cytotoxicity results of hydrogels in HEp-2 cells (average of three independent experiments. * Differences detected by ANOVA analysis with p<0.05).
Figure 7 . Chitosan nanoparticles characterization in terms of size and shape. A : Dynamic light scattering results of three nanoparticle batches. B-E : Scanning transmission electron microscopy images of the nanoparticles.
Figure 8 . Scanning electron microscopy images of hydrogel interaction with chitosan nanoparticles. A-B : starch hydrogel.C-D : starch-chitosan hydrogel. E-F : starch-chitosan-glutaraldehyde. Red arrows point to the nanoparticles.
Figure 9 . Starch-chitosan-glutaraldehyde hydrogel effect in a mouse wound healing model. A : Experiment scheme. B : Comparison of hydrogel effect on wound diameter against control without hydrogel (* Differences detected by ANOVA analysis with p<0.05).