Starch-based microspheres for sustained-release of curcumin: Preparation and cytotoxic effect on tumor cells

•Original starch-based microspheres were developed for controlled delivery of the antitumor drug curcumin.•The fraction released of curcumin is dependent on pH.•The release mechanism was found to be governed by anomalous transport.•Curcumin-loaded microspheres showed higher toxicity toward Caco-2 and HCT-116 tumor cell lines than free curcumin.•Starch-based microspheres have prospective to be efficient delivery device for curcumin in the treatment of colon cancer. Curcumin (CUR) has been proved to be highly cytotoxic against different tumor cell lines. However, its poor solubility in aqueous medium and fast degradation in physiological pH are the common drawbacks preventing its efficient practical use. Herein, we report the development of original microspheres based on the biopolymer starch crosslinked with N,N-methylenebisacrylamide (MBA) to be applied as an efficient delivering system for CUR. The starch-based microspheres showed high loading efficiency even in loading solution with different CUR concentrations. In vitro release assays data showed that the CUR release is governed by anomalous transport (n=0.73) and it is pH-dependent. Cytotoxicity assays showed that starch microspheres could improve the cytotoxicity of CUR toward Caco-2 and HCT-116 tumor cell lines up to 40 times than that found for pure CUR. This behavior was attributed to the slowly and sustained release of CUR from the microspheres.