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In recent years, significant progress has been made in both three-dimensional (3D) printing technologies and the exploration of silk as an ink to produce biocompatible constructs. Combined with the unlimited design potential of 3D printing, silk can be processed into a broad range of functional materials and devices for various biomedical applications. The ability of silk to be processed into various materials, including solutions, hydrogels, particles, microspheres, and fibers, makes it an excellent candidate for adaptation to different 3D printing techniques. This review presents a didactic overview of the 3D printing of silk-based materials, major categories of printing techniques, and their prototyping mechanisms and structural features. In addition, we provide a roadmap for researchers aiming to incorporate silk printing into their own work by summarizing promising strategies from both technical and material aspects, to relate state-of-the-art silk-based material processing with fast-developing 3D printing technologies. Thus, our focus is on elucidating the techniques and strategies that advance the development of precise assembly strategies for silk-based materials. Precise printing (including high printing resolution, complex structure realization, and printing fidelity) is a prerequisite for the digital design capability of 3D printing technology and would definitely broaden the application era of silk, such as complex biomimetic tissue structures, vasculatures, and transdermal microneedles.

Abstract Conductive fibers are needed for the development of flexible electronic and biomedical devices. MXene fibers show great promise for use in such applications because of their high conductivity. Current literature on MXene fiber development highlights the need for improving their mechanical properties and investigation of biocompatibility. Here the use of silk fibroin biopolymer as a MXene formulation additive for the production of MXene fibers is studied. It is found that the favorable silk fibroin–MXene interactions resulted in improved durability, withstanding up to 1 h of high frequency sonication in buffered solutions. Furthermore, fibers with ≈5 wt% silk fibroin displays interesting properties including high conductivity (≈3700 S cm−1), high volumetric capacitance (≈910 F cm−3), and non‐cytotoxicity toward THP‐1 monocytic cells. The results presented here provide an important insight into potential use of MXene fibers in flexible electronics and biomedical applications.

Silk from silkworms and spiders is an exceptionally important natural material, inspiring a range of new products and applications due to its high strength, elasticity, and toughness at low density, as well as its unique conductive and optical properties. Transgenic and recombinant technologies offer great promise for the scaled-up production of new silkworm- and spider-silk-inspired fibres. However, despite considerable effort, producing an artificial silk that recaptures the physico-chemical properties of naturally spun silk has thus far proven elusive. The mechanical, biochemical, and other properties of pre-and post-development fibres accordingly should be determined across scales and structural hierarchies whenever feasible. We have herein reviewed and made recommendations on some of those practices for measuring the bulk fibre properties; skin-core structures; and the primary, secondary, and tertiary structures of silk proteins and the properties of dopes and their proteins. We thereupon examine emerging methodologies and make assessments on how they might be utilized to realize the goal of developing high quality bio-inspired fibres.