Adjustable dual temperature-sensitive hydrogel based on a self-assembly cross-linking strategy with highly stretchable and healable properties.

Developing smart temperature-sensitive hydrogels with a wide response range and highly stretchable and healable properties for simulation of the temperature perception function of human skin remains a great challenge. Here, a novel PNIPAm/PNAGA double-network hydrogel was developed by a self-assembly cross-linking strategy to achieve this goal. Benefiting from the double-network structure and a large number of multiple hydrogen bond interactions between the PNIPAm and PNAGA, the PNIPAm/PNAGA hydrogel realizes wide and adjustable dual temperature response behaviors of 0-32.5 °C (LCST) and 32.5-65 °C (UCST) and exhibits extraordinary mechanical properties with a maximum tensile strength of 51.48 kPa, elongation at break over 1400%, compressive stress over 1 MPa, and Young's modulus approximately 5.51 kPa, and excellent healable properties of nearly 100% temperature-sensitive repair rate. To the best of our knowledge, this is the highest mechanical strength of the reported PNIPNm-based dual temperature-sensitive hydrogels and simultaneously achieved the healable performance of dual temperature-sensitive hydrogels for the first time. The PNIPAm/PNAGA hydrogel displayed superior capability for simulation of the human skin to monitor various ambient temperatures, such as human skin temperature, hot and cold water, a refrigerator, room temperature and oven temperature, indicating promising applications in the fields of electronic skin, wearable device, bionics, etc.

Constructing multi-component organic/inorganic composite bacterial cellulose-gelatin/hydroxyapatite double-network scaffold platform for stem cell-mediated bone tissue engineering.

Bacterial cellulose/hydroxyapatite (BC/HAp) composite had good bioaffinity but its poor mechanical strength limited its widespread applications in bone tissue engineering (BTE). Bacterial cellulose/gelatin (BC/GEL) double-network (DN) composite had excellent mechanical properties but was seldom used in biomedical fields. In this regard, a multi-component organic/inorganic composite BC-GEL/HAp DN composite was synthesized, which combined the advantages of BC/HAp and BC/GEL. Compared with BC/GEL, the BC-GEL/HAp exhibited rougher surface topography and higher thermal stability. Compression and tensile testing indicated that the mechanical strength of the BC-GEL/HAp was greatly reinforced compared with BC/HAp and was even higher than that of BC/GEL. In vitro cell culture demonstrated that the rat bone marrow-derived mesenchymal stem cells (rBMSCs) cultured on the BC-GEL/HAp showed better adhesion and higher proliferation and differentiation potential than the cells cultured on BC/GEL. We hope the BC-GEL/HAp composite could be used as ideal bone scaffold platform or biomedical membrane in the future.