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Abstract Sponge‐like materials made from regenerated silk fibroin biopolymers are a tunable and advantageous platform for in vitro engineered tissue culture and in vivo tissue regeneration. Anisotropic, three‐dimensional (3D) silk fibroin sponge‐like scaffolds can mimic the architecture of contractile muscle. Herein, we use silk fibroin solution isolated from the cocoons ofBombyx morisilkworms to form aligned sponges via directional ice templating in a custom mold with a slurry of dry ice and ethanol. Hydrated tensile mechanical properties of these aligned sponges were evaluated as a function of silk polymer concentration (3% or 5%), freezing time (50% or 100% ethanol), and post‐lyophilization method for inducing crystallinity (autoclaving, water annealing). Hydrated static tensile tests were used to determine Young's modulus and ultimate tensile strength across sponge formulations at two strain rates to evaluate rate dependence in the calculated parameters. Results aligned with previous reports in the literature for isotropic silk fibroin sponge‐like scaffolds, where the method by which beta‐sheets were formed and level of beta‐sheet content (crystallinity) had the greatest impact on static parameters, while polymer concentration and freezing rate did not significantly impact static mechanical properties. We estimated the crystalline organization using molecular dynamics simulations to show that larger crystalline regions may be responsible for strength at low strain amplitudes and brittleness at high strain amplitudes in the autoclaved sponges. Within the parameters evaluated, extensional Young's modulus is tunable in the range of 600–2800 kPa. Dynamic tensile testing revealed the linear viscoelastic region to be between 0% and 10% strain amplitude and 0.2–2 Hz frequencies. Long‐term stability was evaluated by hysteresis and fatigue tests. Fatigue tests showed minimal change in the storage and loss modulus of 5% silk fibroin sponges for more than 6000 min of continuous mechanical stimulation in the linear regime at 10% strain amplitude and 1 Hz frequency. Furthermore, we confirmed that these mechanical properties hold when decellularized extracellular matrix is added to the sponges and when the mechanical property assessments were performed in cell culture media. We also used nano‐computed tomography (nano‐CT) and simulations to explore pore interconnectivity and tortuosity. Overall, these results highlight the potential of anisotropic, sponge‐like silk fibroin scaffolds for long‐term (>6 weeks) contractile muscle culture with an in vitro bioreactor system that provides routine mechanical stimulation. 

Oxygen therapeutics has a range of applications in transfusion medicine and disease treatment. Synthetic molecules and all‐natural or semisynthetic hemoglobin‐based oxygen carriers (HBOCs) have seen success as potential circulating oxygen carriers. However, many early HBOC products stalled in development due to side effects from excess hemoglobin in the blood stream and hemoglobin entering the tissue. To overcome these issues, research has focused on increasing the molecular diameter of hemoglobin by polymerizing hemoglobin molecules or encapsulating hemoglobin in liposomal carriers. This work leverages the properties of silk fibroin, a cytocompatible and nonthrombogenic biopolymer, known to entrap protein‐based cargo, to engineer a fully protein‐based oxygen carrier. Herein, an all‐aqueous solvent evaporation technique is used to form silk particles via phase separation from a bulk polyvinyl alcohol phase. Particle size is tuned, and particles are formed with and without hemoglobin. The encapsulation efficiency and ferrous state of hemoglobin are analyzed, resulting in 60% encapsulation efficiency and a maximum of 20% ferric hemoglobin, yielding 100 μg mL⁻¹active hemoglobin in certain silk fibroin‐HBOCs formulations. The system does not elicit a strong inflammation response in vitro, demonstrating the potential for this particle system to serve as an injectable HBOC. 

Chalcogenide perovskites have attracted increasing research attention in recent years due to their promise of unique optoelectronic properties combined with stability. However, the synthesis and processing of these materials has been constrained by the need for high temperatures and/or long reaction times. In this work, we address the open question of a low-temperature growth mechanism for BaZrS3. Ultimately, a liquid-assisted growth mechanism for BaZrS3 using molten BaS3 as a flux is demonstrated at temperatures ≥540 °C in as little as 5 min. The role of Zr-precursor reactivity and S(g.) on the growth mechanism and the formation of Ba3Zr2S7 is discussed, in addition to the purification of resulting products using a straightforward H2O wash. The extension of this growth mechanism to other Ba-based chalcogenides is shown, including BaHfS3, BaNbS3, and BaTiS3. In addition, an alternative vapor-transport growth mechanism is presented using S2Cl2 for the growth of BaZrS3 at temperatures as low as 500 °C in at least 3 h. These results demonstrate the feasibility of scalable processing for the formation of chalcogenide perovskite thin-films. (DOI: 10.1021/acs.chemmater.3c00494) 

The fields of drug and gene delivery have been revolutionized by the discovery and characterization of polymer-based materials. Polymeric nanomaterials have emerged as a strategy for targeted delivery because of features such as their impressive biocompatibility and improved availability. Use of naturally derived polymers in these nanomaterials is advantageous due to their biodegradability and bioresorption. Natural biopolymer-based particles composed of silk fibroins and other silk fiber-inspired proteins have been the focus of research in drug delivery systems due to their simple synthesis, tunable characteristics, and ability to respond to stimuli. Several silk and silk-inspired polymers contain a high proportion of reactive side groups, allowing for functionalization and addition of targeting moieties. In this review, we discuss the main classes of silk and silk-inspired polymers that are being used in the creation of nanomaterials. We also focus on the fabrication techniques used in generating a tunable design space of silk-based polymeric nanomaterials and detail how that translates into use for drug delivery to several distinct microenvironments.