FTIR spectra of DCA beads and XG–DCA beads were also
investigated as shown in Fig. 4. The spectra of the DCA beads
showed the peaks around 1575–1386 cm−1 of DS, and a remarkable
shift to lower wavenumber of COO− (asymmetric) and
C O C stretching peaks of calcium alginate (Fig. 4b). This
result was similar to our previous studies (Pongjanyakul et al.,
2006). It can be described that amino groups of diclofenac could
protonate inSAdispersion and then interacted with carboxyl and
ether groups of alginate before cross-linking process. Incorporation
of XG at all levels into the DCA beads did not affect the peaks of the DCA beads (Fig. 4c–e). Moreover, these spectra
were similar to the spectra of calcium alginate beads with XG
in Fig. 3c–e. This suggested that the gel matrix structure of XG
and calcium alginate in the beads was still formed after incorporating
DS. These findings indicated that molecular interaction
between SA and XG was able to create a complex matrix structure
in the calcium alginate beads with or without DS, which
caused a change in characteristics of the DCA beads.