Natural halloysite nanotubes modified as an aspirin carrier

Natural halloysite nanotubes (HNTs) modified with 3-aminopropyltriethoxysilane were used as an aspirin carrier. The structure, drug loading and release profiles of samples were characterized by X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and UV-spectrophotometry. The Higuchi model Q = kt(0.5) was employed to analyze the dissolution data in detail. The results indicated that the modification of HNTs could improve the amount of aspirin from 3.84 to 11.98 wt%. The physical state of aspirin was nanocrystalline and amorphous affected by the confined space of HNTs, which significantly enhanced the dissolution rate created by a burst release within the first hour. The linearity of the Higuchi equation indicated that the aspirin release mechanism for modified HNTs was fitted to Fick's diffusion and the dissolution rate was slower than that of natural HNTs. The as-synthesized N-HNTs could have interesting potential application in drug carrier systems.