Synthesis and characterisation of nanohybrids of olsalazine-intercalated Al–Mg layered double hydroxide

In this study, olsalazine (3,3′-azobis 6-hydroxy benzoic acid) was intercalated into Mg–Al layered double hydroxides (LDHs) by ion exchange or coprecipitation methods to obtain olsalazine–LDH nanohybrids. Powder X-ray diffraction (XRD), Fourier transform infrared spectra and elemental analyses indicate a successful intercalation of olsalazine with a vertical orientation. Intercalation of organic anion of olsalazine into Mg–Al LDH caused the interlayer spacing of LDH to increase from 0.884 to 1.665–1.666 nm as determined by XRD studies. Thermogravimetric analyses propose that the thermal stability of the intercalated organic anion of olsalazine is largely improved compared to the pure form before intercalation due to the host–guest interaction involving the hydrogen bond. Furthermore, in vitro drug release experiments in pH 7.4 phosphate buffer solution have been investigated. The drug molecules during dissolution were exchanged with anions in the medium, thus leading to a slow release, much slower than when the same matrix was used simply mixed with the drug.