Nanosized Silk-Magnesium Complexes for Tissue Regeneration

Hierarchical design of silkworm silk for functional composites

Silk-reinforced composites (SRCs) manifest the unique properties of silkworm silk fibers, offering enhanced mechanical strength, biocompatibility, and biodegradability. These composites present an eco-friendly alternative to conventional synthetic materials, with applications expanding beyond biomedical engineering, flexible electronics, and environmental filtration. This review explores the diverse forms of silkworm silk fibers including fabrics, long fibers, and nanofibrils, for functional composites. It highlights advancements in composite design and processing techniques that allow precise engineering of mechanical and functional performance. Despite substantial progress, challenges remain in making optimally functionalized SRCs with multi-faceted performance and understanding the mechanics for reverse-design of SRCs. Future research should focus on the unique sustainable, biodegradable and biocompatible advantages and embrace advanced processing technology, as well as artificial intelligence-assisted material design to exploit the full potential of SRCs. This review on SRCs will offer a foundation for future advancements in multifunctional and high-performance silk-based composites.

Magnesium Ion/Gallic Acid MOF-Laden Multifunctional Acellular Matrix Hydrogels for Diabetic Wound Healing

The main objective for diabetic wound treatment is the design of a functional dressing that scavenges free radicals, alleviates inflammation, and is antibacterial while promoting neovascularization. Herein, a multifunctional acellular matrix hydrogel was prepared with the antimicrobial peptide jelleine-1 and a magnesium ion/gallic acid metal framework to exhibit antioxidant, anti-inflammatory, and proangiogenesis effects in diabetic wounds. The prepared hydrogel termed Gel-J-MOF efficiently released gallic acid in the acidic microenvironment of the diabetic wound, scavenged excess free radicals in vitro, and effectively reduced the levels of inflammation by regulating M2 macrophage polarization in vivo. The antimicrobial peptide jelleine-1 in the composite hydrogel effectively inhibited S. aureus and E. coli in vitro, promoting a suitable microenvironment for wound healing. In the later stage of wound healing, the composite hydrogel stimulated angiogenesis, accelerating the re-epithelialization and collagen deposition in the wound. In conclusion, this multifunctional composite hydrogel provides a regulated microenvironment for treating diabetic wounds and, therefore, has significant potential application promise in the treatment of chronic diabetic wounds.

Controlled release of ionic carrier hydrogels for sequential immunomodulation to facilitate stage-specific treatment of infectious wound

Infected wounds present a significant clinical challenge, exacerbated by antibiotic resistance, which complicates effective treatment. This study introduces a hydrogel (CC/AP@CM) embedded with core-shell bioactive glass nanoparticles designed for the controlled, sequential release of copper (Cu2+) and magnesium (Mg2+) ions. The hydrogel is crosslinked via a Schiff base reaction, endowing it with injectable, self-healing, and adhesive properties. Notably, the bilayer structure of the bioactive glass within the hydrogel allows an initial release of Cu2+ ions to trigger an early-stage pro-inflammatory and antimicrobial response, followed by Mg2+ ions that support tissue repair and an anti-inflammatory environment. This design aligns with natural wound healing stages, promoting a shift in macrophage polarization from the M1 to M2 phenotype, effectively balancing antibacterial defense with tissue regeneration. The hydrogel demonstrated robust antibacterial efficacy against MRSA, increased angiogenesis, and enhanced fibroblast proliferation and migration in vitro. In a murine wound model, it significantly accelerated wound closure and immune activation, including responses from dendritic cells and T cells. These findings suggest that this hydrogel, through its stage-specific immunomodulatory properties and temporally controlled ion release, offers a promising strategy for treating complex wound infections, supporting both immune defense and tissue healing.

Dimethylcurcumin and Copper Sulfate-Loaded Silk Nanoparticles for Synergistic Therapy against Breast Cancer

Dimethylcurcumin (ASC-J9) is an organic active pharmaceutical ingredient with anti-inflammatory, antioxidant, and antitumor effects. However, its application has been significantly hindered by poor solubility in aqueous solutions, a short in vivo half-life, low bioavailability after oral administration, and limited accumulation and absorption in target areas. Nano-drug delivery systems can serve as drug carriers to enhance drug delivery, addressing these challenges with improved efficacy and reduced adverse effects. In this study, a microfluidic swirl mixer is used to prepare silk fibroin composite nanoparticles containing ASC-J9 and copper sulfate (CuS), and the effects of different process parameters on silk fibroin nanoparticles (SNPs) were explored and optimized. The synthesized composite ASC-J9-CuS@SNPs exhibited a mean particle diameter of 180 ± 10 nm and PDI of 0.20 ± 0.03. Two-dimensional/three-dimensional (2D/3D) cell experiments showed that the composite nanomaterials have excellent biocompatibility and antitumor activity with a noticeable cancer cell specificity. In vivo experiments showed that ASC-J9-CuS@SNPs effectively controlled tumor growth without causing damage to blood cells and vital organs. Both in vitro and in vivo experiments demonstrated that the anticancer effect was enhanced by photo thermotherapy. The current study provides a promising strategy for using silk fibroin as nanocarriers for breast cancer therapy.

Optimization of Metal-Based Nanoparticle Composite Formulations and Their Application in Wound Dressings

Metal-based nanoparticles (MNPs) have great potential for applications in wound healing and tissue engineering, and due to their unique structures, high bioactivities, and excellent designability characteristics, an increasing number of studies have been devoted to modifying these species to generate novel composites with desirable optical, electrical, and magnetic properties. However, few systematic and detailed reviews have been performed relating to the modification approaches available for MNPs and their resulting composites. In this review, a comprehensive summary is performed regarding the optimized modification formulations of MNPs for application in wound dressings, and the techniques used to prepare composite wound dressings are discussed. In addition, the safety profiles of the novel nanocomposite formulations and the limitations of the reported systems are evaluated. More importantly, a number of solution strategies are proposed to address these limitations. Overall, this review provides new ideas for the design of MNPs to facilitate their application in the field of skin tissue repair, and also looks into the future direction of MNPs in the biomedical field.

Adhesive silk fibroin/magnesium composite films and their application for removable wound dressing

Silk fibroin is a naturally abundant biomaterial renowned for its excellent biocompatibility and biodegradability, making it a promising candidate for biomedical applications like wound dressings. However, traditional silk fibroin materials often lack sufficient mechanical strength, adhesion, and the ability to modulate inflammation and oxidative stress-factors crucial for effective wound healing. To address these limitations, regenerated silk fibroin/magnesium ion [RSF/Mg(II)] composite films were developed by incorporating Mg(II) ions into RSF solutions. These films were characterized using Raman spectroscopy, mechanical testing, and biocompatibility assessments, and their wound-healing efficacy was evaluated in a mouse skin defect model. The RSF/Mg(II) composite films exhibited superior adhesion, higher transparency, and enhanced mechanical flexibility compared to pristine RSF films. They also demonstrated anti-inflammatory and antioxidative properties, effectively reducing cell apoptosis and reactive oxygen species levels in vitro. In vivo, the RSF/Mg Mg(II) composite films significantly accelerated wound healing in mice, improving epidermal thickness, collagen deposition, and promoting blood vessel formation. This study highlights the potential of RSF/Mg(II) composite films as advanced wound dressings with improved biocompatibility and biological activity, offering valuable insights for the development of Mg(II) ion-based biomaterials in wound healing and tissue regeneration applications.

Accelerated scarless wound healing by dynamical regulation of angiogenesis and inflammation with immobilized asiaticoside and magnesium ions in silk nanofiber hydrogels

It remains a challenge to effectively regulate the complicated microenvironment during the wound healing process. The optimization of synergistic action of angiogenesis and inflammation is considered critical for quicker scarless wound regeneration. Here, the silk nanofiber (SNF) acts as a multifunctional carrier to load hydrophobic asiaticoside (AC) and hydrophilic Mg2+, and also serves as an element to assemble injectable hydrogels, forming a bioactive matrix with improved angiogenic and anti-inflammatory capacities (SNF-AC-Mg). Mg2+ and AC distributed homogeneously inside the silk nanofiber hydrogels without compromising the mechanical performance. Both Mg2+ and AC released slowly to continuously tune both angiogenic and inflammatory behaviors. The hydrogels exhibited good biocompatibility, inflammation inhibition, and pro-angiogenic properties in vitro, suggesting the synergistic bioactivity of AC and Mg2+. In vivo analysis revealed that the synergistic action of AC and Mg2+ resulted in better M2-type polarization of macrophages and angiogenesis during the inflammatory phase, while effectively achieving the inhibition of excessive accumulation of collagen and scar formation during the remodeling phases. The quicker scarless regeneration of the defects treated with SNF-AC-Mg implies the priority of SNFs in designing bioactive niches with complicated cues, which will favor the functional recovery of different tissues in the future.

Mechanical biomimetic silk nano fiber-magnesium ion complex/hydroxyethylcellulose/glycerol hydrogel dressing with angiogenic capacity for accelerating scarless diabetic wound healing

Quick scarless healing remains a key issue for diabetic wounds. Here, a stretchable elastomeric hydrogel dressing composed of hydroxyethylcellulose (HEC), silk nano fiber-magnesium ion complex (Mg2+-SNF) and glycerol (Gly) was developed to optimize mechanical niche, anti-inflammatory and angiogenic behavior simultaneously. The composite hydrogel dressing exhibited skin-like elasticity (175.1 ± 23.9 %) and modulus (156.7 ± 2.5 KPa) while Mg2+-SNF complex endowed the dressing with angiogenesis, both favoring quick scarless skin regeneration. In vitro cell studies revealed that the hydrogel dressing stimulated fibroblast proliferation, endothelial cell migration and vessel-like tube formation, and also induced anti-inflammatory behavior of macrophages. In vivo results revealed accelerated healing of diabetic wounds. The improved granulation ingrowth and collagen deposition suggested high quality repair. Both thinner epidermal layer and low collagen I/III ratio of the regenerated skin confirmed scarless tissue formation. This bioactive hydrogel dressing has promising potential to address the multifaceted challenges of diabetic wound management.

Nanosized Silk-Magnesium Complexes for Promotion of Angiogenic and Osteogenic Activities

Injectable hydrogels with osteogenic and angiogenetic properties are of interest in bone tissue engineering. Since the bioactivity of ions is concentration-dependent, nanosized silk-magnesium (Mg) complexes were previously developed and assembled into hydrogels with angiogenic capabilities but failed to control both osteogenic and angiogenetic activities effectively. Here, nanosized silk particles with different sizes were obtained by using ultrasonic treatment to control silk-Mg coordination and particle formation, resulting in silk-Mg hydrogels with different types of bioactivity. Fourier transform infrared and X-ray diffraction results revealed that different coordination intensities were present in the different complexes as a basis for the differences in activities. Slow Mg ion release was controlled by these nanosized silk-Mg complexes through degradation. With the same amount of Mg ions, the different silk-Mg complexes exhibited different angiogenic and osteogenic capacities. Complexes with both angiogenic and osteogenic capacities were developed by optimizing the sizes of the silk particles, resulting in faster and improved quality of bone formed in vivo than complexes with the same composition of silk and Mg but only angiogenic or osteogenic capacities. The biological selectivity of silk-Mg complexes should facilitate applications in tissue regeneration.

Magnesium Ion-Doped Mesoporous Bioactive Glasses Loaded with Gallic Acid Against Myocardial Ischemia/Reperfusion Injury by Affecting the Biological Functions of Multiple Cells

Introduction

Excessive generation of reactive oxygen species (ROS) following myocardial ischemia-reperfusion (I/R) can result in additional death of myocardial cells. The rapid clearance of ROS after reperfusion injury and intervention during subsequent cardiac repair stages are crucial for the ultimate recovery of cardiac function.

Methods

Magnesium-doped mesoporous bioactive glasses were prepared and loaded with the antioxidant drug gallic acid into MgNPs by sol-gel method. The antioxidant effects of MgNPs/GA were tested for their pro-angiogenic and anti-inflammatory effects based on the release characteristics of GA and Mg2+ from MgNPs/GA. Later, we confirmed in our in vivo tests through immunofluorescence staining of tissue sections at various time points that MgNPs/GA exhibited initial antioxidant effects and had both pro-angiogenic and anti-inflammatory effects during the cardiac repair phase. Finally, we evaluated the cardiac function in mice treated with MgNPs/GA.

Results

We provide evidence that GA released by MgNPs/GA can effectively eliminate ROS in the early stage, decreasing myocardial cell apoptosis. During the subsequent cardiac repair phase, the gradual release of Mg2+ from MgNPs/GA stimulated angiogenesis and promoted M2 macrophage polarization, thereby reducing the release of inflammatory factors.

Conclusion

MgNPs/GA acting on multiple cell types is an integrated solution for comprehensive attenuation of myocardial ischaemia-reperfusion injury and cardiac function protection.

Silk Nanofiber Scaffolds with Multiple Angiogenic Cues to Accelerate Wound Regeneration

Niches with multiple physical and chemical cues can influence the fate of cells and tissues in vivo. Simulating the in vivo niche in the design of bioactive materials is a challenge, particularly to tune multiple cues simultaneously in the same system. Here, an assembly strategy was developed to regulate multiple cues in the same scaffold based on the use of two silk nanofiber components that respond differently during the fabrication processes. An aqueous solution containing the two components, amorphous silk nanofibers (ASNFs) and β-sheet-rich silk nanofibers (BSNFs), was sequentially treated with an electrical field and freeze-drying processes where the BSNFs oriented to the electrical field, while the ASNFs formed stable porous structures during the lyophilization process to impact the mechanical properties. Bioactive cargo, such as deferoxamine (DFO), was loaded on the BSNFs to enrich cell responses with the scaffolds. The in vitro results revealed that the loaded DFO and the anisotropic structures with improved mechanical properties resulted in better vascularization than those of the scaffolds without the anisotropic features. The multiple cues in the scaffolds provided angiogenic niches to accelerate wound healing.