Recently, tissue engineering (TE) is one of the fast growing research fields due the accessibility of extra-molecular matrix (ECM) at cellular and molecular level with valuable potential prospective of hydrogels. The enhancement in the production of hydrogel-based cellular scaffolds with the structural composition of ECM has been accelerated with involvement of rapid prototyping techniques. Basically, the recreation of ECM has been derived from naturally existed or synthetic hydrogel-based polymers. The rapid utilization of hydrogels in TE puts forward the scope of bioprinting for the fabrication of the functional biological tissues, cartilage, skin and artificial organs. The main focus of the researchers is on biofabrication of the biomaterials with maintaining the biocompatibility, biodegradability and increasing growth efficiency. In this review, biological development in the structure and cross-linking connections of natural or synthetic hydrogels are discussed. The methods and design criteria that influence the chemical and mechanical properties and interaction of seeding cells before and after the implantations are also demonstrated. The methodology of bioprinting techniques along with recent development has also been reviewed. In the end, some capabilities and shortcomings are pointed out for further development of hydrogels-based scaffolds and selection of bioprinting technology depending on their application.

Design, materials, and performance are important factors in the research of bone tissue scaffolds. This work briefly describes the bone scaffolds and their anatomic structure, as well as their biological and mechanical characteristics. Furthermore, we reviewed the characteristics of metal materials, inorganic materials, organic polymer materials, and composite materials. The importance of the bionic design in preoperative diagnosis models and customized bone scaffolds was also discussed, addressing both the bionic structure design (macro and micro structure) and the bionic performance design (mechanical performance and biological performance). Materials and performance are the two main problems in the development of customized bone scaffolds. Bionic design is an effective way to solve these problems, which could improve the clinical application of bone scaffolds, by creating a balance between mechanical performance and biological performance.

This study investigates the effects of 3D printing parameters on the mechanical properties (predominantly tensile properties) of a commercial polylactic acid-based wood fiber composite material known as wood filament. The influence of printing parameters, including layer thickness, infill density, printing speed, and nozzle temperature on the mechanical properties, is studied, and the design of the experiment (DOE) is made through Taguchi L₉ orthogonal array. The specimens for the tensile test are fabricated by the material extrusion (MEX) 3D printer, which is also known as fused deposition modeling (FDM) or fused filament fabrication (FFF). After conducting the tensile test, this research considers four significant outcomes: tensile strength, maximum load, elastic modulus, and elongation at break. Further analysis of the obtained results from mechanical testing is performed through analysis of variance (ANOVA) to determine the significance of each parameter on the mechanical properties. Moreover, prediction and optimization are conducted to verify the obtained results from the DOE. Furthermore, scanning electronic microscopy (SEM) is used to analyze the fracture zones, cracks, voids, and fiber/matrix adhesion of the FDM fabricated parts which demonstrates that the lower layer thickness provides better adhesion and fewer voids between successive layers and thus exhibits better mechanical performance. Graphical abstract