The FTIR spectra show that the functional groups of GO/Alg and cGO/Alg are very similar as expected (Fig 7). Thus, a broad peak around 3250 cm−1 corresponds to OH stretching vibration, the bands at 1600 cm−1 and 1414 cm−1 correspond to symmetric and asymmetric COO− stretching vibration of carboxylate salt group, and the peak at 1030 cm−1 due to the stretching vibration of C−O−C groups respectively. The shoulder peak at 1087 cm−1 is attributed to the C−O stretching of sodium alginate. However, the intensity of the peak corresponding to the carbonyl esters (1735–1750 cm−1) increases considerably indicating that this group plays a more important role in cGO/Alg due to the GO crosslinking via divalent cations by coordination chemistry and a slight shift of this peak from 1750 to 1746 cm-1 is observed.