Acid-induced release of curcumin from calcium containing nanotheranostic excipient

Poor water solubility is believed one of the most critical problems of numerous promising pharmaceutical ingredients in their successful clinical utilization. Nanomedicine holds considerable promise to address this challenge, because it extends the therapeutic window of hydrophobic drugs through nanonization approach. Recently, the integration of diagnostic agents with smart therapeutic nanocarriers is also an emerging research arena to simultaneously visualize diseased tissues, achieve site specific drug release and track the impact of therapy. In this study, we have developed a biocompatible smart theranostic nanosystem which transports a highly promising hydrophobic drug (curcumin) in response to mildly acidic environment. As calcium is a main constituent of human body, hence we exploited the reversible calcium chelate formation tendency of divalent calcium to load and unload curcumin molecules. Moreover, an emerging T1 contrast agent is also tethered onto the surface of nanocarrier to realize MRI diagnosis application. In-vitro cell experiments revealed a significantly high chemotherapeutic efficiency of curcumin nanoformulation (IC50; 1.67 μg/mL), whereas free curcumin was found ineffective at the corresponding concentration (IC50; 29.72 μg/mL). MR imaging test also validated the performance of resulting system. Our strategy can be extended for the targeted delivery of other hydrophobic pharmaceutical ingredients.