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Abstract Biological processes are inherently dynamic, necessitating biomaterial platforms capable of spatiotemporal control over cellular organization and matrix stiffness for accurate study of tissue development, wound healing, and disease. However, most in vitro platforms remain static. In this study, a dynamic biomaterial platform comprising a stiffening hydrogel is introduced and achieved through a stepwise approach of addition followed by light‐mediated crosslinking, integrated with an elastomeric substrate featuring strain‐responsive lamellar surface patterns. Employing this platform, the response of human induced pluripotent stem cell‐derived cardiomyocytes (hIPSC‐CMs) is investigated to dynamic stiffening from healthy to fibrotic tissue stiffness. The results demonstrate that culturing hIPSC‐CMs on physiologically relevant healthy stiffness significantly enhances their function, as evidenced by increased sarcomere fraction, wider sarcomere width, significantly higher connexin‐43 content, and elevated cell beating frequency compared to cells cultured on fibrotic matrix. Conversely, dynamic matrix stiffening negatively impacts hIPSC‐CM function, with earlier stiffening events exerting a more pronounced hindering effect. These findings provide valuable insights into material‐based approaches for addressing existing challenges in hIPSC‐CM maturation and have broader implications across various tissue models, including muscle, tendon, nerve, and cornea, where both cellular alignment and matrix stiffening play pivotal roles in tissue development and regeneration. 

Abstract Embedded bioprinting is an emerging technology for precise deposition of cell-laden or cell-only bioinks to construct tissue like structures. Bioink is extruded or transferred into a yield stress hydrogel or a microgel support bath allowing print needle motion during printing and providing temporal support for the printed construct. Although this technology has enabled creation of complex tissue structures, it remains a challenge to develop a support bath with user-defined extracellular mimetic cues and their spatial and temporal control. This is crucial to mimic the dynamic nature of the native tissue to better regenerate tissues and organs. To address this, we present a bioprinting approach involving printing of a photocurable viscous support layer and bioprinting of a cell-only or cell-laden bioink within this viscous layer followed by brief exposure to light to partially crosslink the support layer. This approach does not require shear thinning behavior and is suitable for a wide range of photocurable hydrogels to be used as a support. It enables multi-material printing to spatially control support hydrogel heterogeneity including temporal delivery of bioactive cues (e.g. growth factors), and precise patterning of dense multi-cellular structures within these hydrogel supports. Here, dense stem cell aggregates are printed within methacrylated hyaluronic acid-based hydrogels with patterned heterogeneity to spatially modulate human mesenchymal stem cell osteogenesis. This study has significant impactions on creating tissue interfaces (e.g. osteochondral tissue) in which spatial control of extracellular matrix properties for patterned stem cell differentiation is crucial. 

Abstract Polymeric systems displaying spontaneous formation of surface wrinkling patterns are useful for a wide range of applications, such as diffraction gratings, flexible electronics, smart adhesives, optical devices, and cell culture platforms. Conventional fabrication techniques for wrinkling patterns involves multitude of processing steps and impose significant limitations on fabrication of hierarchical patterns, creating wrinkles on 3D and nonplanar structures, the scalability of the manufacturing process, and the integration of wrinkle fabrication process into a continuous manufacturing process. In this work, 4D printing of surface morphing hydrogels enabling direct fabrication of wrinkling patterns on curved and/or 3D structures with user‐defined and spatially controlled pattern geometry and size is reported. The key to successful printing is to tailor the photopolymerization time and partial crosslinking time of the hydrogel inks. The interplay between crosslinker concentration and postprinting crosslinking time allow for the control over wrinkling morphology and the characteristic size of the patterns. The pattern alignment is controlled by the print strut size—the size of the solid material extruded from the print nozzle in the form of a line. To demonstrate the utility of the approach, tunable optical devices, a solvent/humidity sensor for microchips, and cell culture platforms to control stem cell shape are fabricated. 

Abstract Extrusion‐based 3D printing of polymeric biomaterials has emerged as a promising approach for the fabrication of complex tissue engineering constructs. However, the large pore and feature size lead to low cell seeding efficiency and limited control of spatial distribution of cells within the scaffolds. We developed hybrid scaffolds that are composed of 3D‐printed layers and airbrushed fibrous membranes. Airbrushing time was adjusted to fabricate low (L), medium (M), and high (H) density membranes to effectively control stem cell infiltration. When two distinct populations of stem cells were seeded from top or bottom of the scaffolds, scaffolds composed ofLLLmembranes showed gradual mixing of the cells with depth, whereasLHLmembranes led to two distinct regions of cells separated by theHmembrane. Our results demonstrate that fibrous membranes incorporated within 3D‐printed layers enable user‐defined and spatially controlled cell compositions within hybrid scaffolds. 

Biodegradable polymers offer a promising solution to the growing issue of global microplastic pollution. To effectively replace conventional plastics, it is essential to develop strategies for tuning the properties of biodegradable polymers without relying on additives. Biaxial stretching promotes anisotropic crystallization in polymer domains, thereby altering the mechanical performance of polymer blends. In this study, we employed a design of experiment (DoE) approach to investigate the effects of biaxial stretching at three drawing temperatures (Tds) and draw ratios (λs) on a biodegradable blend of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT), aiming to optimize both the strength and ductility. The DoE analysis revealed that the composition, the λ, the interaction between the λ and composition, and the interaction between the Td and composition significantly affect the elongation at break (εBreak). For the stress at break (σBreak), the most influential factors were the interaction between the λ and PLA concentration; a three-way interaction among the λ, PLA, and Td; the Td; the λ; and finally the PLA concentration alone. The optimal εBreak and σBreak were achieved at a λ = 5 × 5 and Td = 110 °C, with a composition of 10% PLA and 90% PBAT. The stretched samples exhibited higher crystallinity compared to the pressed samples across all compositions. This work demonstrates that in addition to the composition, the processing parameters, such as the λ and Td, critically influence the mechanical properties, enabling performance enhancements without the need for compatibilizers or toxic additives. 

We present an extrusion-based embedded bioprinting strategy to fabricate dense cellular constructs within bioactive MeHA hydrogels containing human bone microparticles, providing a scalable platform for bone tissue engineering. 

Solution and melt 3D printing techniques were compared for fabricating PCL/HA scaffolds. Solution printing resulted in porous, rougher scaffolds, while melt printing produced stiffer scaffolds with enhanced bone formation.