Modification of gellan gum films by halloysite: physicochemical evaluation and drug permeation properties

The aim of this study was to determine the potential of gellan gum (GG) and halloysite (HS) dispersions at different mixing ratios and to investigate the potential of GG-HS dispersions in film formation. To this end, the dispersions and films were characterized. The dispersions formed films with large particles ranging from 3 to 4 μm in size, with a zeta potential of ∼-35 mV. The GG-HS films were fabricated using a solvent-casting technique, which generated films with a white opaque appearance and rough surface. The GG-HS films were formed via hydrogen bonding and electrostatic interactions at the inner cavity and outer surface, as confirmed by ATR-FTIR spectroscopy and X-ray diffractometry. The %water uptake and erosion of the GG-HS film decreased with increasing HS content, whereas both puncture strength and elongation were increased in the GG-HS ratios of 1:0.4 and 1:1.2. Moreover, addition of HS into the GG films could possibly decrease drug permeability coefficient when using higher HS ratio in acidic and neutral media. These results suggested that HS modifies the characteristics of the GG used to coat modified-release tablets.