In situ assembly of Mt-HAP drug carrier with pH-responsive sustained release properties

The Mt-HAP composites were achieved by combining layered montmorillonite (Mt) and hydroxyapatite (HAP) nanoparticles produced by in situ assembly technique. Amoxicillin (AMX) loading and release experiment proved that the synthetic Mt-HAP composites demonstrated high drug loading ability and pH-responsive sustained release property. The AMX load of original Mt was 18.5 mg g⁻¹, while that of Mt-HAP grew to 49.1 mg g⁻¹. Experiments in simulated gastric fluid (pH 1.2) release indicated that Mt drug carrier having a higher release rate of AMX within the initial 2 h. But after that, the drug release rate of AMX from Mt-HAP has a greater value (about 65% over 12 h) than that of Mt (about 50% over 12 h) because of the dissolution of HAP under acidic circumstance. However, the cumulative sustained release rate of Mt-HAP in simulated intestinal fluid (pH 6.8) over 12 h was only 30%, and the drug release amount of Mt was still about 49%. Compared to Mt@AMX, the drug release rate of Mt-HAP @ AMX is sensitive to changes in pH. The findings claimed that the Mt-HAP composite exhibited extreme potential as a drug carrier for controllable drug delivery. (paper)