Chengdu University

Musculoskeletal disorders (MSDs), such as osteoporosis, cartilage degeneration, and tendon injuries, are common worldwide and have a significant impact on patients' quality of life. These conditions are frequently associated with aging, trauma, or chronic diseases. They are typically characterized by slow and limited self-repair, particularly in tissues like cartilage and tendons, which exhibit low regenerative potential. Traditional treatment methods, such as implantable scaffolds, often face challenges related to incomplete tissue integration and inadequate adaptation to dynamic biomechanical conditions. Shape memory scaffolds (SMSs) have emerged as promising candidates for repairing musculoskeletal tissues, due to their unique ability to respond to external stimuli, such as temperature, light, and pH. These materials can adapt to irregular tissue defects and dynamically adjust to biomechanical requirements during the healing process, thereby potentially supporting tissue regeneration. This review discusses the advantages of SMSs in musculoskeletal system reconstruction, emphasizing their mechanical responsiveness, adaptability, and bioactive potential. Furthermore, recent advancements in SMS-based scaffolds and the role of 4D printing in enhancing their functionality are systematically reviewed. Finally, we propose future research directions aimed at enabling more effective and personalized treatments for MSDs.

Intervertebral disc degeneration (IVDD) is a leading cause of lower back pain, characterized by the ferroptosis of nucleus pulposus cells (NPCs) and imbalance in reactive oxygen species (ROS) metabolism. Icariin (ICA), an active compound from traditional Chinese medicine, scavenges ROS and inhibits ferroptosis, but its poor water solubility and low bioavailability limit clinical use. A dual-crosslinked hydrogel (HP@ICA) is developed to address these challenges. Cyclodextrin is integrated into polyvinyl alcohol to enhance ICA loading via hydrophobic interactions. Methacrylic acid and phenylboronic acid are incorporated into hyaluronic acid, enabling dynamic bonding with polyvinyl alcohol. Ultraviolet crosslinking creates a secondary crosslinked hydrogel with pH and ROS responsiveness, self-healing properties, and improved ICA solubility, increasing its water solubility tenfold. Enhanced solubility boosts ICA's free radical scavenging capacity by 103 %, suppressing ferroptosis and promoting NP cell regeneration, as demonstrated by reduced iron ion concentrations, lower malondialdehyde levels, and restored glutathione peroxidase 4 activity. Ferroptosis inhibition facilitates type II collagen production in NP cells. Mechanistic studies reveal activation of the Nrf2-GPX4 pathway as key to regeneration. These findings suggest a promising regenerative therapeutic approach for IVDD.

Water dilution induces undesirable precipitation in egg white, hindering its industrial use. This study investigated the inhibitory effect of alkaline pH (9.5-10.5) on this phenomenon. Increasing the buffer pH dramatically reduced the turbidity and particle size (from 1395.4 nm to 418.2 nm) of egg white solutions. This was attributed to enhanced electrostatic repulsion, as evidenced by a more negative zeta-potential (from -8.0 mV to -23.8 mV). Paradoxically, precipitate mass initially increased at pH 9.5 despite improved solution clarity, contradicting the conventional expectation that higher solids content yields higher turbidity. This was resolved by discovering a fundamental shift in aggregate structure: the opaque, flocculent precipitates in the control, characterized by high surface hydrophobicity and a loose microstructure, transformed into a transparent, hydrogel-like matrix at alkaline pH. This new structure, composed of a dense nanoparticle network with low surface hydrophobicity, minimized light scattering. Quantitative proteomics revealed this transformation was driven by a stoichiometric shift, not a change in protein types. Alkaline pH solubilized primary turbidity-causing proteins (e.g., Metalloproteinase inhibitor 3) while promoting an ordered assembly of others, a process potentially mediated by the electrostatic bridging role of lysozyme. This study uncovers a dual mechanism of electrostatic solubilization and structural reorganization, offering a practical, pH-based strategy to control egg white precipitation.