Zhongjin Ni

Extrusion-based bioprinting requires hydrogel materials with suitable rheological behavior, structural stability, and bio-related properties; however, the relationships among composition, network structure, and printing performance in multicomponent hydrogel systems remain insufficiently understood. In this study, a GG/SS/PVA/GEL composite hydrogel was developed and optimized using single-factor experiments combined with Box–Behnken response surface methodology. Rheological analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy were further used to characterize the optimized system. The optimal formulation was identified as 0.14 g of GG, 0.60 g of SS, and 2.3 g of PVA. This formulation achieved a comprehensive score of 87 with a prediction error of less than 5%. The optimized hydrogel exhibited pronounced shear-thinning behavior, a printing fidelity of 98.6–101.4%, a maximum swelling ratio of approximately 403.5%, and an enzymatic degradation rate of 68.5%, together with a relatively uniform interconnected porous structure. These results indicate that the optimized composite hydrogel is a promising printable material candidate and provide a useful basis for formulation design in extrusion-based hydrogel systems.

Superhydrophobic coatings have attracted a lot of attention due to their excellent self-cleaning and anti-fouling capabilities. However, the preparation processes for several superhydrophobic coatings are intricate and expensive, which restricts their usefulness. In this work, we present a straightforward technique for creating durable superhydrophobic coatings that can be applied to a variety of substrates. The addition of C9 petroleum resin to a styrene-butadiene-styrene (SBS) solution lengthens the SBS backbone and undergoes a cross-linking reaction to form a dense spatial cross-linked structure, improving the storage stability, viscosity, and aging resistance of the SBS. The combined solution functions as a more stable and effective adhesive. Using a two-step spraying technique, the hydrophobic silica (SiO₂) nanoparticles solution was applied to the surface to create durable nano-superhydrophobic coatings. Additionally, the coatings have excellent mechanical, chemical, and self-cleaning stability. Furthermore, the coatings have wide application prospects in the fields of water–oil separation and corrosion prevention.

Cellulose nanofibers (NFC) have attracted special attention in the field of extrusion-based three-dimensional (3D) bioprinting due to their good biocompatibility, excellent mechanical properties, and outstanding shear-thinning property. In this study, by mixing cellulose nanofibers suspension with sodium alginate (SA) and gelatin (GEL) solution, five groups of composite bio-inks with different NFC concentrations were prepared. The effects of NFC on the performance of the SA/GEL matrix hydrogels were analyzed by morphological observation, rheological property testing, mechanical property testing, swelling property testing, and printability analysis. The rheological results showed that the addition of NFC noticeably increased the viscosity of biological inks with low shear rates; therefore, the printed scaffolds maintained their structure better during the 3D printing process. After crosslinking with calcium chloride (CaCl2), the fidelity of the NFC/SA/GEL composite hydrogel structure was better than that of the SA/GEL hydrogel. Moreover, the structural properties were strengthened, and the mechanical stabilities of the composite hydrogels improved when NFC was added. Therefore, this study provided an easy way to improve the printability of extrusion-based 3D printing and the potential use of nanocellulose.