The role of coordination chemistry in the development of innovative Gallium-based bioceramics: the case of Curcumin

Curcumin, an active ingredient in the traditional Ayurvedic herbal remedy [Curcuma longa L.], is nowadays also employed in western medicine for its pleiotropic activities, ranging from anticancer to its free radical scavenger ability. These features are related to curcumin's function as a metal chelator, especially being selective for hard Lewis acids, such as Ga3+ which has interesting pharmacological activities. We report the synthesis and characterization of bioactive gel and mesoporous Ga-containing phospho-silicate glasses loaded with curcumin, in which, for the first time, the design of novel drug delivery systems takes advantage of coordination chemistry. In particular, it was found that: (i) there is a direct correlation between the external surface area and the amount of loaded curcumin; (ii) the presence of Ga3+ species on the surface increases the quantity of drug molecules uploaded and slows down their release in the biological medium (SBF), hinting a coordination-like interaction between curcumin and the surface metal ions; (iii) curcumin molecules released in the SBF solution stabilize Ga3+ ions, avoiding their precipitation.