Effects of Surface Pretreatment on Structure and Release Performances of Mg-Al Hydrotalcites

The drug delivery materials (5-FU/LDHs) were obtained by intercalation of 5-Fluorouracil (5-FU) into the sheets of Mg-Al-NO3 hydrotalcites (LDHs) by ion-exchange method. The surface of the LDHs was modified with weak acid pretreatment. The influence of the acid-pretreatment on the surface chemical characteristics and microstructure of the LDHs was determined using X-ray diffractometry (XRD), Fourier transform-infrared spectrometer (FTIR), Thermo gravimetric and Differential scanning calorimeter (TG-DSC), Scanning electron microscopy (SEM) and point of zero charge (pH(PZC)). The results showed that the interlayer spaces of the 5-FU/LDHs were expanded from 0.858 to 1.064 nm. 5-FU2 anions were intercalated into the brucite sheets of the LDHs as a monolayer arranged alternately with a constant angle through hydrogen bonding and electrostatic attraction. Average particle size became smaller and permanent charge density of the sheets increased after the acid-pretreatment of the carrier. The release mechanism of the 5-FU was discussed. The in vitro releasing behavior of the 5-FU/LDHs materials was involved in physical diffusion, ions exchange and drug dissolution and so on. The release performances and thermostability could be improved after acid pretreatment.