(607e) Functionalized Alumina Particles for pH-Responsive Drug Delivery

pH-responsive particles for anti-cancer drug delivery were created using alumina particles functionalized with silane coupling agents. Three types of silane coupling agents with varying chain lengths and terminal groups were used. XPS analysis was done to confirm surface coupling of the silanes onto the particles. In order to observe the effects of the presence of various terminal groups the uptake and release of the positively charged anti-cancer drug Doxorubicin (Dox) and the negatively charged dye sulforhodamine 101 (SR101) were studied. Uptake experiments were performed while incubating the particles in a dilute solution of each compound. Afterwards, release experiments were carried out at 37˚C in phosphate buffered saline solutions (0.16 M) at pH values of 5.0 and 7.4. The loading ability observed during the uptake experiments was found to be directly proportional to the silane concentration used during functionalization. Zeta potential measurements revealed that the charge on the particles was directly proportional to both the silane type as well as the silane concentration used during functionalization. Long chain silanes were identified to have the best response to pH and showed a two-fold difference in the relative amounts released when comparing trials run at pH 5.0 and pH 7.4. These results suggest that charge interactions between the loaded compound and the terminal silane groups influence not only the rates of uptake and release, but also the pH-responsive character of these particles.