Fabrication of surface-functionalizable amphiphilic curcumin nanogels for biosensing and biomedical applications

Nanogels, nanosized water-soluble physically and/or chemically cross-linked polymeric networks, have been widely prepared, characterized and studied in recent years due to their attractive properties, especially in biomedical applications as delivery vehicle for therapeutic and diagnostic purposes. Here, we present a facile new synthetic strategy to prepare ultra-small amphiphilic nanogels with tunable properties from a bioactive natural material (curcumin, with its well-known functionalities and health promoting activities) and a biocompatible maleic anhydride-based polymer. Our approach is based on a combination of chemical cross-linking, hydrophobic interaction and self-assembly. The nanogels were investigated for their physicochemical properties and colloidal stability under different pH values and salt concentrations as well as the in vitro cytotoxicity. The results indicated negative surface charge (as indicated by gel electrophoresis and laser Doppler anemometry with a zeta potential of − 60 mV) nanogels of small sizes (d_h = 5.6 nm) with high colloidal stability at a wide range of pH values and NaCl concentrations. Additionally, the nanogels were not toxic up to concentration 100 μg/mL for BEAS-2B and A549 cells. The relatively facile preparation, high colloidal stability, ultra-small size and possible surface modification, functionalization and/or bioconjugation makes the obtained nanogels of great importance, especially in sensing and biomedical applications.