Electrochemical deposition to construct a nature inspired multilayer chitosan/layered double hydroxides hybrid gel for stimuli responsive release of protein

In this study, we report a single electrodeposition process to fabricate multilayered chitosan/layered double hydroxides (LDHs) hybrid hydrogels for stimuli responsive protein release. LDHs nanoplatelets with a regular hexagonal shape were synthesized by a hydrothermal method, and a model protein, insulin, was adsorbed on the surface of the LDHs (INS-LDHs) via electrostatic interactions. The insulin loading ratio could reach 20% (w/w); the INS-LDHs were characterized by energy dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG) and zeta potential measurements. Co-electrodeposition of chitosan and INS-LDHs generated an inorganic and organic composite hydrogel with a multilayered structure, as revealed by scanning electron microscopy (SEM). The hybrid hydrogel dramatically reduced the burst release of insulin from INS-LDHs. Notably, the release of insulin was sensitive to the presence of anions, pH, and external potentials. These results suggest that co-electrodeposition of a stimuli-responsive polymer and nanoplatelets is an alternative and facile method to construct hierarchically structured hybrid hydrogels and demonstrate the great potential of the multilayered structure in drug delivery.