To fabricate a recyclable supported catalyst based on gold nanoparticles (AuNPs) and gelatin hydrogel (HG) composites, a ferrocene (Fc)-containing tetrablock copolymer [P(NCHO-b-NFc-b-NTEG-b-NCHO)] was used as both reducing and stabilizing agents for AuNPs and as a crosslinker for HG. First, the effects of Fc-containing polymers, including homopolymer PNFc and copolymer P(NCHO-b-NFc-b-NTEG-b-NCHO), and different solvent systems on the morphology and aggregation of AuNPs were examined by using ultraviolet-visible spectroscopy, transmission electron microscopy, and dynamic light scattering. Second, two strategies (blending and soaking) were applied to prepare different AuNPs/HG composites (AuNPs-HG), and their structure and properties were studied by using various techniques including scanning electron microscopy, X-ray diffraction, and thermogravimetry. Finally, the catalytic performance and reusability of AuNPs-HG-1 (via blending) and AuNPs-HG-2 (via soaking) were evaluated utilizing the model catalytic reduction of 4-nitrophenol to 4-aminophenol by NaBH 4 . Results indicated that P(NCHO-b-NFc-b-NTEG-b-NCHO) dissolved in N,Ndimethylformamide was the optimal reductant and stabilizer to prepare AuNPs. The in situ reduction of Au III ions to Au 0 particles was very essential for the fabrication of AuNPs-HG in terms of hydrogel pore size, Au 0 distribution and immobilization stability, and hydrogel thermal stability. Due to the stronger interactions among AuNPs, P(NCHO-b-NFc-b-NTEG-b-NCHO), and gelatin molecules in the blending strategy, AuNPs-HG-1 showed better mechanical stability and catalytic performance and more reusing cycles than AuNPs-HG-2. This work highlights the design and fabrication of robust recyclable supported AuNP catalyst by using eco-friendly Fccontaining HGs.

Hydrogels developed as stimuli-responsive drug delivery systems (DDSs) are increasingly concerned research focus in many fields such as chemistry, functional materials and biomedicine. Herein, we report the fabrication, characterization and drug release property of new gelatin composite hydrogels by using biocompatible gelatin and the doxorubicin (DOX)-loaded micelles of a redox-responsive side-chain ferrocene (Fc)-containing amphiphilic diblock copolymer PNFc-b-PNTEG (Fig. 1). The self-assembly method was firstly adopted to prepare the DOX-loaded micelles of PNFc-b-PNTEG with oxidation-sensitive release property, and the DOX-loaded gelatin composite hydrogels were then successfully fabricated by using blending and soaking methods, respectively. The formed hydrogels were characterized by many techniques including scanning electron microscope, energy-dispersive spectroscopy, differential scanning calorimetry, thermogravimetry and swelling test. The successful encapsulation of the DOX-containing micelles in the gelatin matrix was demonstrated, and the prepared composite hydrogels exhibited improved thermal stability, faster swelling speed and higher swelling ratios. The oxidation-triggered controlled in vitro release of DOX from the composite hydrogels was confirmed by using FeCl3 at different concentrations as an oxidizing agent. The composite hydrogels could act as excellent solid carriers to guarantee the sustained-release effect of DOX, and it is feasible to keep the DOX molecules with high concentration at the specific site for a long period (20 days or so). Thus, the present composite hydrogels are anticipated to be good candidates as redox-responsive DDSs.

Hydrogels developed as stimuli-responsive drug delivery systems (DDSs) are increasingly concerned research focus in many fields such as chemistry, functional materials and biomedicine. Herein, we report the fabrication, characterization and drug release property of new gelatin composite hydrogels by using biocompatible gelatin and the doxorubicin (DOX)-loaded micelles of a redox-responsive side-chain ferrocene (Fc)-containing amphiphilic diblock copolymer PNFc-b-PNTEG (Fig. 1). The self-assembly method was firstly adopted to prepare the DOX-loaded micelles of PNFc-b-PNTEG with oxidation-sensitive release property, and the DOX-loaded gelatin composite hydrogels were then successfully fabricated by using blending and soaking methods, respectively. The formed hydrogels were characterized by many techniques including scanning electron microscope, energy-dispersive spectroscopy, differential scanning calorimetry, thermogravimetry and swelling test. The successful encapsulation of the DOX-containing micelles in the gelatin matrix was demonstrated, and the prepared composite hydrogels exhibited improved thermal stability, faster swelling speed and higher swelling ratios. The oxidation-triggered controlled in vitro release of DOX from the composite hydrogels was confirmed by using FeCl3 at different concentrations as an oxidizing agent. The composite hydrogels could act as excellent solid carriers to guarantee the sustained-release effect of DOX, and it is feasible to keep the DOX molecules with high concentration at the specific site for a long period (20 days or so). Thus, the present composite hydrogels are anticipated to be good candidates as redox-responsive DDSs.