Supramolecular phenoxy-alkyl maleate-based hydrogels and their enzyme/pH-responsive curcumin release†
Low-molecular-weight gelators that self-assemble via non-covalent interactions have been attracting significant attention due to their good biocompatibility, low toxicity, inherent biodegradability as well as their convenience of design. Enzymatically digestible and pH-sensitive hydrogels play an important role in controlled drug delivery applications. In the present study, we synthesized four simple phenoxy alkyl maleate amphiphiles with various hydrophobic chain lengths (C6–C12). The gelation ability of four amphiphiles was examined in a phosphate buffer solution; among them, the maleates with C10 and C12 chain lengths exhibited gelation ability at the minimum gelation concentrations (MGC) of 1.6 and 1.3% w/v, respectively. These hydrogelators have shown strong three-dimensional cross-linked networks that can capture water molecules. The obtained supramolecular hydrogels were thoroughly characterized using differential scanning calorimetry (DSC), scanning electron microscopy, density functional theory (DFT) calculation, X-ray diffraction, and rheological studies. More importantly, curcumin, a hydrophobic drug, was encapsulated (1% w/v) into the gel core, and its subsequent release was achieved through gel-to-sol transition induced by lipozyme (biological stimuli). Additionally, the drug-loaded hydrogel exhibited pH-responsive drug release behavior. The drug release behavior was monitored by employing UV-Vis spectroscopy. Overall, the prepared hydrogelators may be useful in the stimuli-responsive delivery of hydrophobic drugs.