Biomimetic Nanofibrillar Hydrogel with Cell-Adaptable Network for Enhancing Cellular Mechanotransduction, Metabolic Energetics, and Bone Regeneration

Ligand Dissociation of Metal-Complex Photocatalysts toward pH-Photomanipulation in Dynamic Covalent Hydrogels for Printing Reprocessable and Recyclable Devices

Dynamic covalent hydrogels are gaining attention for their potential in smart materials, soft devices, electronics, and more thanks to their impressive mechanical properties, biomimetic structures, and dynamic behavior. However, a significant challenge lies in designing precise and efficient dynamic photochemistry for their preparation, allowing for complex structures and control over the dynamic process. Herein, we propose a general and straightforward orthogonal dynamic covalent photochemistry strategy for preparing high-performance printable dynamic covalent hydrogels, thereby broadening their advanced applications. This photochemical strategy uses a bifunctional photocatalyst to initiate radical polymerization and release ligands through a rapid light-mediated dissociation mechanism. This process leads to a controlled increase in system pH from mildly acidic to alkaline conditions within one hundred seconds, which in turn triggers the pH-sensitive model reactions of boronic acid/diol complexation and Knoevenagel condensation. The orthogonal photochemistry enables the formation of interpenetrated and conjoined networks, significantly enhancing the mechanical properties of the hydrogels. The reversible bonds formed during the process, i.e., boronic ester and unsaturated ketone bonds, confer excellent self-healing, reprocessable, and recyclable properties on the hydrogels through photochemical pH variations. Furthermore, this rapid, controlled fabrication process and dynamic behavior are highly compatible with printing techniques, enabling the design of adaptive and recyclable sensors with different structures. These advancements are promising for various material science, medicine, and engineering applications.

Cross-Linking Methods of the Silk Protein Hydrogel in Oral and Craniomaxillofacial Tissue Regeneration

BACKGROUND

Craniomaxillofacial tissue defects are clinical defects involving craniomaxillofacial and oral soft and hard tissues. They are characterized by defect-shaped irregularities, bacterial and inflammatory environments, and the need for functional recovery. Conventional clinical treatments are currently unable to achieve regeneration of high-quality oral craniomaxillofacial tissue. As a natural biomaterial, silk fibroin (SF) has been widely studied in biomedicine and has broad prospects for use in tissue regeneration. Hydrogels made of SF showed excellent water retention, biocompatibility, safety and the ability to combine with other materials.

METHODS

To gain an in-depth understanding of the current development of SF, this article reviews the structure, preparation and application prospects in oral and craniomaxillofacial tissue regenerative medicine. It first briefly introduces the structure of SF and then summarizes the principles, advantages and disadvantages of the different cross-linking methods (physical cross-linking, chemical cross-linking and double network structure) of SF. Finally, the existing research on the use of SF in tissue engineering and the prospects of using SF with different cross-linking methods in oral and craniomaxillofacial tissue regeneration are also discussed.

CONCLUSIONS

This review is intended to show the advantages of SF hydrogels in tissue engineering and provides theoretical support for establishing novel and viable silk protein hydrogels for regeneration.

Multilevel Micronanoscale Texture Effects on Fly Wing Membrane-Water Droplet Interaction

The wettable surface or nonwettable surface that is derived from a multilevel micronanoscale structure is abundant in nature and biomimetic commodities. Those hoverflies with the seta-coated wing membrane detached from impacting free-falling raindrops were observed in static states. A hoverfly wing membrane with well-ordered setae was identified as a robust nonwettable surface, and the static water contact angle θ on the wing membrane at the microscopic scale is 136.84 ± 0.98°. Hoverfly wing membrane-water droplet interaction with the actual truth and the theoretical models was discussed and indicated that the theoretical calculation might not state the actual situation, arising from the membrane or seta-drop-bubble interaction and those multilevel micronanoscale structure characteristics on the wing membrane. Detailed investigation on nonwettable surface-wettable surface transformation with surface CaCO3 accumulation in a carbonization reaction and the characteristic transformation toward the hoverfly wing membrane with the multilevel micronanoscale structure was carried out. Then, the CaCO3 accumulation on PDMS texture films was carried out and the static water contact angle θ was tested. Those observations offer ideas to fabricate artificial films with a multilevel micronanoscale structure that could obtain some characteristics, i.e., nonwettable surface-wettable surface transformation.