Loading and release of 5-fluorouracil from HY zeolites with varying SiO2/Al2O3 ratios

Zeolite Y with different silica to alumina ratios varying from 5 to 60 was used as a host for the chemotherapy drug, 5-fluorouracil. The 5-fluorouracil content in the zeolites was approximately 90-110 mg/g as determined by thermogravimetric analysis. Nitrogen adsorption-desorption measurements were used to measure the surface area and the pore volume of the zeolites before and after 5-fluorouracil loading. The decrease in surface areas and pore volumes after drug loading was attributed to the inclusion of 5-fluorouracil in the zeolite pores. FTIR spectroscopy provided evidence of molecular level interactions of the 5-fluorouracil with the zeolite. Al-27 NMR indicated that the 5-fluorouracil interacted with the zeolite through the extraframework aluminum sites. Release profiles under physiological conditions were also conducted and indicated that the aluminum content was critical in determining the extent of release of 5-fluorouracil. HY-5 with the lowest SiO2/Al2O3 released less than 5% of the loaded 5-fluorouracil while HY-30 and HY-60 released approximately 56% and 63% of the loaded 5-FU, respectively. (C) 2012 Elsevier Inc. All rights reserved.