No abstract

Scaffold‐based tissue engineering is a promising strategy to address the rapidly growing demand for bone implants, but developing scaffolds with bone extracellular matrix‐like structures, suitable mechanical properties, and multiple biological activities remains a huge challenge. Here, it is aimed to develop a wood‐derived composite scaffold with an anisotropic porous structure, high elasticity, and good antibacterial, osteogenic, and angiogenic activities. First, natural wood is treated with an alkaline solution to obtain a wood‐derived scaffold with an oriented cellulose skeleton and high elasticity, which can not only simulate collagen fiber skeleton in bone tissue but also greatly improve the convenience of clinical implantation. Subsequently, chitosan quaternary ammonium salt (CQS) and dimethyloxalylglycine (DMOG) are further modified on the wood‐derived elastic scaffold through a polydopamine layer. Among them, CQS endows the scaffold with good antibacterial activity, while DMOG significantly improves the scaffold's osteogenic and angiogenic activities. Interestingly, the mechanical characteristics of the scaffolds and the modified DMOG can synergistically enhance the expression of yes‐associated protein/transcriptional co‐activator with PDZ binding motif signaling pathway, thereby effectively promoting osteogenic differentiation. Therefore, this wood‐derived composite scaffold is expected to have potential application in the treatment of bone defects.

The commonly used chitin whiskers (CHWs) prepared by the acid hydrolysis method are easy to agglomerate in an alkaline matrix, which limits their applications in many aspects. Herein, maleation chitin whiskers (mCHWs) with lots of −COOH groups were designed, which can stably exist and homogeneously disperse in the alkaline chitin matrix due to their relatively strong electronegativities. Subsequently, the CHWs and mCHWs were utilized as reinforcing fillers to enhance the mechanical strength of the chitin hydrogel. As expected, the CHWs played an extremely limited role in reinforcing the chitin hydrogel. Conversely, due to good dispersibility and strong interfacial interaction, the mCHWs exhibited a significantly superior enhancement effect on the chitin hydrogel. Moreover, the tensile strength and modulus of the asprepared mCHW/chitin composite hydrogels were strongly dependent on the content of mCHWs, and the highest values of 5.8 ± 0.2 and 5.2 ± 0.6 MPa were obtained with 3 wt % mCHW content, which are higher than those of polysaccharide hydrogels reported in the most literature. Importantly, both CHWs and mCHWs can facilitate the adhesion, proliferation, and differentiation of mouse embryo osteoblast precursor (MC3T3-E1) cells. Moreover, the mCHWs also play these promoting effects in a contentdependent manner. Interestingly, CHWs and mCHWs mainly contain −NH 2 and −COOH groups, respectively; as a result, surface protein adsorption and calcium-phosphate mineralization are different. But there are very small differences in cell adhesion, proliferation, and differentiation between the corresponding 3%CHW/chitin and 3%mCHW/chitin composite hydrogels. This work provides a promising strategy to construct a polysaccharide nanocomposite hydrogel with robust mechanical strength and osteogenesis for potential application as an artificial periosteum.

No abstract