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BACKGROUND: Aspirin is a classic non-steroidal anti-inflammatory drug. Appropriate doses of aspirin can regulate immunity and promote osteogenesis. The preparation of bone tissue engineering materials, which can release aspirin, regulate the immune microenvironment of the bone defect area and accelerate the repair of the bone defect, and is a current research focus. OBJECTIVE: To prepare a novel hydrogel scaffold that can modulate the immune microenvironment and quickly repair the bone defect area. METHODS: Hydrogel scaffolds containing 0%, 10% and 20% of nano-hydroxyapatite/aspirin/polyvinyl alcohol/gelatin/sodium alginate were prepared. The microstructure, porosity, chemical composition, crystal structure, drug release properties, mechanical properties, swelling properties and degradation properties of the hydrogel scaffolds were characterized. The biocompatibility of the hydrogel scaffolds was evaluated by cell proliferation and cytotoxicity experiments. RESULTS AND CONCLUSION: (1) Scanning electron microscope and porosity results showed that hydrogel scaffolds in the 0% nano-hydroxyapatite group and 10% nano-hydroxyapatite group had better biomimetic hierarchical porous structure, pore connectivity, and porosity. (2) The results of Fourier transform infrared spectroscopy and X-ray diffraction showed that the raw materials in the hydrogel scaffold were combined by physical and chemical double crosslinking, and the crystal phase structure of nano-hydroxyapatite was not be destroyed. (3) The results of mechanical properties showed that the 10% nanohydroxyapatite group had the best compressive modulus and compressive strength. (4) The results of drug release properties showed that the cumulative release rate of aspirin decreased with the increase of nano-hydroxyapatite, but the drug burst release rate decreased and the sustained release time prolonged. (5) The results of swelling properties and degradation properties showed that with the increase of nano-hydroxyapatite, the swelling rate and degradation rate of hydrogel scaffolds of each group decreased. (6) Using the hydrogel scaffold extract to culture mouse pre-osteoblasts, the results of cell proliferation and cytotoxicity experiments showed that the hydrogel scaffold extract could promote cell proliferation, without cytotoxicity. (7) It is concluded that 10% nanohydroxyapatite hydrogel scaffolds have better bionic characterization and biocompatibility, and are expected to be used as bone tissue engineering scaffolds for further studies of osteogenesis and immunomodulatory potential. [ABSTRACT FROM AUTHOR]

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In this study, a three‐dimensional nitrogen‐doped graphene (3DNG)‐Fe3+/poly(acrylic acid‐co‐N,N‐dimethylacrylamide) (3DNG‐Fe3+/P(AA‐co‐DMA)) hydrogel with strong flexibility and excellent self‐healing property was prepared. The 3DNG‐Fe3+/P(AA‐co‐DMA) hydrogel was characterized by Fourier transform infrared spectrometer (FT‐IR), scanning electron microscope (SEM). The specific surface area and pore size distribution of the 3DNG‐Fe3+/P(AA‐co‐DMA) hydrogel were measured by using Brunauer‐Emmett‐Teller (BET) method. The experimental results demonstrate that when 6 mol% FeCl3 was added, the breaking strain of Fe3+/P(AA‐co‐DMA) hydrogel reaches 1149 %, and the tensile strength reaches 689 kPa. Furthermore, the recovery degree of Fe3+/P(AA‐co‐DMA) hydrogel was almost 100 % after 24 h. The supercapacitors based on 3DNG‐Fe3+/P(AA‐co‐DMA) hydrogel have a specific capacitance value of 231.8 F g−1 at 1 A⋅g−1, and conductivity is 0.053 S⋅cm−1. When the power density is 5 kW kg−1, the energy density of the device is 38.7 Wh kg−1. [ABSTRACT FROM AUTHOR]

The formation of double cross-linked (ionic and covalent) gelatin (G) and chitosan (CS) hydrogels was studied. The covalent cross-linking consists in the reaction between the carbonyl groups of glutaraldehyde with the free amine groups from the two polymers; the ionic cross-linking is based on sulfate anions interaction with protonated amine groups of the polymers solubilized in acetic acid. The structural and morphological characterization of the obtained hydrogels was performed using FT-IR and scanning electron microscopy (SEM). The influence of different parameters on the cross-linking density (indirectly assessed by water swelling capacity) and the ability to include hydrosoluble active principles such as the ratio between polymers (G/CS), the amount of ionic cross-linker, and the cross-linking time were investigated. The morphological and structural characteristics, mechanical stability, elasticity of the network, the interaction with aqueous weak alkaline solutions, and the capacity to load and release a model drug were analyzed for the obtained hydrogels. Rheological tests were performed to study the mechanical stability of the hydrogels and the results show, generally, elastic and stable networks. [ABSTRACT FROM PUBLISHER]