Dimension‐Based Design of Melt Electrowritten Scaffolds

The electrohydrodynamic stabilization of direct‐written fluid jets is explored to design and manufacture tissue engineering scaffolds based on their desired fiber dimensions. It is demonstrated that melt electrowriting can fabricate a full spectrum of various fibers with discrete diameters (2–50 µm) using a single nozzle. This change in fiber diameter is digitally controlled by combining the mass flow rate to the nozzle with collector speed variations without changing the applied voltage. The greatest spectrum of fiber diameters was achieved by the simultaneous alteration of those parameters during printing. The highest placement accuracy could be achieved when maintaining the collector speed slightly above the critical translation speed. This permits the fabrication of medical‐grade poly(ε‐caprolactone) into complex multimodal and multiphasic scaffolds, using a single nozzle in a single print. This ability to control fiber diameter during printing opens new design opportunities for accurate scaffold fabrication for biomedical applications.     

Lignin‐Based Direct Ink Printed Structural Scaffolds

3D printing of lignocellulosic biomass (cellulose, hemicellulose, and lignin) has attracted increasing attention by using this abundant, sustainable, and ecofriendly material. While cellulose can be easily tailored into a highly viscous ink for 3D printing, after solvent evaporation, the final printed structures become highly porous, fragile, and easily fall apart in water due to its hydrophilic nature. Lignin, another crucial component of natural lignocellulose, has not yet been reported for ink printing due to its unfavorable rheological behavior. Herein, a low‐cost direct ink printing strategy is developed to fabricate lignin‐based 3D structures with lignin no further refined and a more compact microstructure as well as different functionalities compared with printed cellulose. By using a soft triblock copolymer as the crosslinking agent, the rheology of lignin‐based inks can be adjusted from soft to rigid, and even enables vertical printing which requires stiff and self‐supporting features. The lignin‐based inks contain less water (≈40 wt%) and exhibit a much denser, stiffer structure, resulting in a wet tensile strength of ≈30 MPa, compared to only ≈0.6 MPa for printed cellulose. In addition, the unique macromolecular structure of lignin also demonstrates significantly improved stability in water and under heat, as well as UV‐blocking performance.     

Aggregation‐Induced Electrochemiluminescence by Metal‐Binding Protein Responsive Hydrogel Scaffolds

Functionalized hydrogels have aroused general interest due to their versatile applications in biomaterial fields. This work reports a hydrogel network composed of gold nanoclusters linked with bivalent cations such as Ca²⁺, Mg²⁺, and Zn²⁺. The hydrogel exhibits both aggregation‐induced emission (AIE) and aggregation‐induced electrochemiluminescence (AIECL) effects. Most noteworthy, the AIECL effect (≈50‐fold enhancement) is even more significant than the corresponding AIE effect (approximately fivefold enhancement). Calmodulin, a Ca²⁺ binding protein, may efficiently regulate the AIECL dynamics after specific binding of the Ca²⁺ linker, with the linear range from 0.3 to 50 µg mL^?1 and a limit of detection of 0.1 µg mL^?1. Considering the important roles of bivalent cations in the life system, these results may pave a new avenue for the design of a biomolecule‐responsive AIECL‐type hydrogel with multifunctional biomedical purposes.     

Engineered Fibrillar Fibronectin Networks as Three‐Dimensional Tissue Scaffolds

Extracellular matrix (ECM) proteins, and most prominently, fibronectin (Fn), are routinely used in the form of adsorbed pre‐coatings in an attempt to create a cell‐supporting environment in both two‐ and three‐dimensional cell culture systems. However, these protein coatings are typically deposited in a form which is structurally and functionally distinct from the ECM‐constituting fibrillar protein networks naturally deposited by cells. Here, the cell‐free and scalable synthesis of freely suspended and mechanically robust three‐dimensional (3D) networks of fibrillar fibronectin (fFn) supported by tessellated polymer scaffolds is reported. Hydrodynamically induced Fn fibrillogenesis at the three‐phase contact line between air, an Fn solution, and a tessellated scaffold microstructure yields extended protein networks. Importantly, engineered fFn networks promote cell invasion and proliferation, enable in vitro expansion of primary cancer cells, and induce an epithelial‐to‐mesenchymal transition in cancer cells. Engineered fFn networks support the formation of multicellular cancer structures cells from plural effusions of cancer patients. With further work, engineered fFn networks can have a transformative impact on fundamental cell studies, precision medicine, pharmaceutical testing, and pre‐clinical diagnostics.     

ZnO/Nanocarbons‐Modified Fibrous Scaffolds for Stem Cell‐Based Osteogenic Differentiation

Currently, mesenchymal stem cells (MSCs)‐based therapies for bone regeneration and treatments have gained significant attention in clinical research. Though many chemical and physical cues which influence the osteogenic differentiation of MSCs have been explored, scaffolds combining the benefits of Zn²⁺ ions and unique nanostructures may become an ideal interface to enhance osteogenic and anti‐infective capabilities simultaneously. In this work, motivated by the enormous advantages of Zn‐based metal–organic framework‐derived nanocarbons, C‐ZnO nanocarbons‐modified fibrous scaffolds for stem cell‐based osteogenic differentiation are constructed. The modified scaffolds show enhanced expression of alkaline phosphatase, bone sialoprotein, vinculin, and a larger cell spreading area. Meanwhile, the caging of ZnO nanoparticles can allow the slow release of Zn²⁺ ions, which not only activate various signaling pathways to guide osteogenic differentiation but also prevent the potential bacterial infection of implantable scaffolds. Overall, this study may provide new insight for designing stem cell‐based nanostructured fibrous scaffolds with simultaneously enhanced osteogenic and anti‐infective capabilities.     

Super‐Elastic Magnetic Structural Color Hydrogels

Structural color hydrogels are promising candidates as scaffold materials for tissue engineering and for matrix cell culture and manipulation, while their super‐elastic features are still lacking due to the irreconcilable interfere of the precursor and the self‐assembly unit. This hinders many of their practical biomedical applications where elasticity is required. Herein, hydrophilic and size‐controllable Fe₃O₄@poly(4‐styrenesulfonic acid‐co‐maleic acid) (PSSMA)@SiO₂ magnetic response photonic crystals are fabricated as the assembly units of the structural color hydrogels by orderly packing of core–shell colloidal nanocrystal clusters via a two‐step facile synthesis approach. These units are capable of responding instantaneously to an external magnetic field with resistance to interference of ions, thus, by integrating super‐elastic hydrogels, super‐elastic magnetic structural color hydrogels can be achieved. The structural color arises from the dynamic ordering of the magnetic nanoparticles through the contactless control of external magnetic field, allowing regional polymerization of hydrogels via changing orientation and strength of external magnetic field. These regionally polymerized super‐elastic magnetic structural color hydrogels can work as anti‐counterfeiting labels with super‐elastic identification, which may be widely used in the future.     

Skin‐Like Stretchable Fuel Cell Based on Gold‐Nanowire‐Impregnated Porous Polymer Scaffolds

Skin‐like energy devices can be conformally attached to the human body, which are highly desirable to power soft wearable electronics in the future. Here, a skin‐like stretchable fuel cell based on ultrathin gold nanowires (AuNWs) and polymerized high internal phase emulsions (polyHIPEs) scaffolds is demonstrated. The polyHIPEs can offer a high porosity of 80% yet with an overall thickness comparable to human skin. Upon impregnation with electronic inks containing ultrathin (2 nm in diameter) and ultrahigh aspect‐ratio (>10 000) gold nanowires, skin‐like strain‐insensitive stretchable electrodes are successfully fabricated. With such designed strain‐insensitive electrodes, a stretchable fuel cell is fabricated by using AuNWs@polyHIPEs, platinum (Pt)‐modified AuNWs@polyHIPEs, and ethanol as the anode, cathode, and fuel, respectively. The resulting epidermal fuel cell can be patterned and transferred onto skin as “tattoos” yet can offer a high power density of 280 µW cm^?2 and a high durability (>90% performance retention under stretching, compression, and twisting). The results presented here demonstrate that this skin‐thin, porous, yet stretchable electrode is essentially multifunctional, simultaneously serving as a current collector, an electrocatalyst, and a fuel host, indicating potential applications to power future soft wearable 2.0 electronics for remote healthcare and soft robotics.