High-throughput fabrication of silk fibroin/hydroxypropyl methylcellulose (SF/HPMC) nanofibrous scaffolds for skin tissue engineering

A novel designed nanofibrous mat based on hydroxypropyl methyl cellulose incorporating mango peel extract for potential use in wound care system

Skin tissue is damaged by factors such as burns, physical injuries and diseases namely diabetes. Infection and non-healing of burn wounds and lack of angiogenesis in diabetic wounds lead to extensive injuries and death. Therefore, the design of wound dressings with antibacterial and restorative capabilities is very important. In this study, nanofibers (NFs) including polyurethane (PU) and hydroxypropyl methyl cellulose (HPMC) were prepared with different ratios and Mango peel extract (MPE) loaded into NFs by electrospinning method. The morphology, chemical structure, porosity, degradation, water vapor permeability, mechanical properties, wettability, antioxidant activity and some cell studies and evaluation of their antibacterial properties were investigated. The optimal mat (PU90/HPMC10) had a defect-free morphology with homogeneous NFs. Furthermore, it showed improved biodegradability, water vapor permeability and porosity compared to other Mats. All NFs were non-toxic with hydrophilic behavior in the cellular environment and had acceptable hemocompatibility. The PU90/HPMC10/20 % optimal scaffold had significantly higher cell viability and proliferation than other samples and also had a higher antibacterial ability against pathogenic bacteria S. aureus (17 mm) and E. coli (11 mm). All these findings confirm that the produced NF mats, especially those loaded with MPE, have a high potential to be used as an effective wound dressing.

The wound healing effect of polycaprolactone-chitosan scaffold coated with a gel containing Zataria multiflora Boiss. volatile oil nanoemulsions

AIMS

Thymus plant is a very useful herbal medicine with various properties such as anti-inflammatory and antibacterial. Therefore, the properties of this plant have made this drug a suitable candidate for wound healing. In this study, hydroxypropyl methylcellulose (HPMC) gel containing Zataria multiflora volatile oil nanoemulsion (neZM) along with polycaprolactone/chitosan (PCL-CS) nanofibrous scaffold was used, and the effect of three experimental groups on the wound healing process was evaluated. The first group, HPMC gel containing neZM, the second group, PCL-CS nanofibers, and the third group, HPMC gel containing neZM and bandaged with PCL-CS nanofibers (PCL-CS/neZM). Wounds bandaged with common sterile gas were considered as control.

METHODS

The nanoemulsion was synthesized by a spontaneous method and loaded into a hydroxypropyl methylcellulose (HPMC) gel. The DLS test investigated the size of these nanoemulsions. A PCL-CS nanofibrous scaffold was also synthesized by electrospinning method then SEM and contact angle tests investigated morphology and hydrophilicity/hydrophobicity of its surface. The animal study was performed on full-thickness skin wounds in rats, and the process of tissue regeneration in the experimental and control groups was evaluated by H&E and Masson's trichrome staining.

RESULTS

The results showed that the nanoemulsion has a size of 225±9 nm and has an acceptable dispersion. The PCL-CS nanofibers synthesized by the electrospinning method also show non-beaded smooth fibers and due to the presence of chitosan with hydrophilic properties, have higher surface hydrophobicity than PCL fibers. The wound healing results show that the PCL-CS/neZM group significantly reduced the wound size compared to the other groups on the 7th, 14th, and 21st days. The histological results also show that the PCL-CS/neZM group could significantly reduce the parameters of edema, inflammation, and vascularity and increase the parameters of fibrosis, re-epithelialization, and collagen deposition compared to other groups on day 21.

CONCLUSION

The results of this study show that the PCL-CS/neZM treatment can effectively improve wound healing.

Advanced Applications of Silk-Based Hydrogels for Tissue Engineering: A Short Review

Silk has been consistently popular throughout human history due to its enigmatic properties. Today, it continues to be widely utilized as a polymer, having first been introduced to the textile industry. Furthermore, the health sector has also integrated silk. The Bombyx mori silk fibroin (SF) holds the record for being the most sustainable, functional, biocompatible, and easily produced type among all available SF sources. SF is a biopolymer approved by the FDA due to its high biocompatibility. It is versatile and can be used in various fields, as it is non-toxic and has no allergenic effects. Additionally, it enhances cell adhesion, adaptation, and proliferation. The use of SF has increased due to the rapid advancement in tissue engineering. This review comprises an introduction to SF and an assessment of the relevant literature using various methods and techniques to enhance the tissue engineering of SF-based hydrogels. Consequently, the function of SF in skin tissue engineering, wound repair, bone tissue engineering, cartilage tissue engineering, and drug delivery systems is therefore analysed. The potential future applications of this functional biopolymer for biomedical engineering are also explored.

Recent advances in 3D printed cellulose-based wound dressings: A review on in vitro and in vivo achievements

Chronic wounds, especially diabetic ulcers, pose a significant challenge in regenerative medicine. Cellulose derivatives offer remarkable wound management properties, such as effective absorption and retention of wound exudates, maintaining an optimal moisture environment crucial for successful chronic wound regeneration. However, conventional dressings have limited efficacy in managing and healing these types of skin lesions, driving scientists to explore innovative approaches. The emergence of 3D printing has enabled personalized dressings that meet individual patient needs, improving the healing process and patient comfort. Cellulose derivatives meet the demanding requirements for biocompatibility, printability, and biofabrication necessary for 3D printing of biologically active scaffolds. However, the potential applications of nanocellulose and cellulose derivative-based inks for wound regeneration remain largely unexplored. Thus, this review provides a comprehensive overview of recent advancements in cellulose-based inks for 3D printing of personalized wound dressings. The composition and biofabrication approaches of cellulose-based wound dressings are thoroughly discussed, including the functionalization with bioactive molecules and antibiotics for improved wound regeneration. Similarly, the in vitro and in vivo performance of these dressings is extensively examined. In summary, this review aims to highlight the exceptional advantages and diverse applications of 3D printed cellulose-based dressings in personalized wound care.

Development of Large Hollow Particles for Pulmonary Delivery of Cyclosporine A

The purpose of this study was to prepare large hollow particles (LHPs) by spray drying for pulmonary delivery of cyclosporine A (CsA), using L-Leucine (LEU) and hydroxypropyl methylcellulose (HPMC) as excipients and ammonium bicarbonate (AB) as a porogen. The prepared LHPs were spherical particles composed of both CsA and LEU on the surface and HPMC on the inner layer. The formulation of CsA-LEU-0.8HPMC-AB as typical LHPs showed excellent in vitro aerodynamic performance with a minimum mass median aerodynamic diameter (MMAD) of 1.15 μm. The solubility of CsA-LEU-0.8HPMC-AB was about 5.5-fold higher than that of raw CsA, and the dissolution of CsA-LEU-0.8HPMC-AB suggested that the drug was released within 1 h. The cell viability of the A549 cell line showed that CsA-LEU-0.8HPMC-AB was safe for delivering CsA to the lungs. In addition, inhalation administration of CsA-LEU-0.8HPMC-AB with the Cmax and AUC0-∞ increasing by about 2-fold and 2.8-fold compared with the oral administration of Neoral® could achieve therapeutic drug concentrations with lower systemic exposure and significantly improve the in vivo bioavailability of CsA. From these findings, the LHPs, with the advantage of avoiding alveolar macrophage clearance, could be a viable choice for delivering CsA by inhalation administration relative to oral administration.

Sustained Delivery of the Antiviral Protein Griffithsin and Its Adhesion to a Biological Surface by a Silk Fibroin Scaffold

The protein Griffithsin (Grft) is a lectin that tightly binds to high-mannose glycosylation sites on viral surfaces. This property allows Grft to potently inhibit many viruses, including HIV-1. The major route of HIV infection is through sexual activity, so an important tool for reducing the risk of infection would be a film that could be inserted vaginally or rectally to inhibit transmission of the virus. We have previously shown that silk fibroin can encapsulate, stabilize, and release various antiviral proteins, including Grft. However, for broad utility as a prevention method, it would be useful for an insertable film to adhere to the mucosal surface so that it remains for several days or weeks to provide longer-term protection from infection. We show here that silk fibroin can be formulated with adhesive properties using the nontoxic polymer hydroxypropyl methylcellulose (HPMC) and glycerol, and that the resulting silk scaffold can both adhere to biological surfaces and release Grft over the course of at least one week. This work advances the possible use of silk fibroin as an anti-viral insertable device to prevent infection by sexually transmitted viruses, including HIV-1.

Recent advances in tendon tissue engineering strategy

Tendon injuries often result in significant pain and disability and impose severe clinical and financial burdens on our society. Despite considerable achievements in the field of regenerative medicine in the past several decades, effective treatments remain a challenge due to the limited natural healing capacity of tendons caused by poor cell density and vascularization. The development of tissue engineering has provided more promising results in regenerating tendon-like tissues with compositional, structural and functional characteristics comparable to those of native tendon tissues. Tissue engineering is the discipline of regenerative medicine that aims to restore the physiological functions of tissues by using a combination of cells and materials, as well as suitable biochemical and physicochemical factors. In this review, following a discussion of tendon structure, injury and healing, we aim to elucidate the current strategies (biomaterials, scaffold fabrication techniques, cells, biological adjuncts, mechanical loading and bioreactors, and the role of macrophage polarization in tendon regeneration), challenges and future directions in the field of tendon tissue engineering.

Silk Fibroin Combined with Electrospinning as a Promising Strategy for Tissue Regeneration

The development of tissue engineering scaffolds is of great significance for the repair and regeneration of damaged tissues and organs. Silk fibroin (SF) is a natural protein polymer with good biocompatibility, biodegradability, excellent physical and mechanical properties and processability, making it an ideal universal tissue engineering scaffold material. Nanofibers prepared by electrospinning have attracted extensive attention in the field of tissue engineering due to their excellent mechanical properties, high specific surface area, and similar morphology as to extracellular matrix (ECM). The combination of silk fibroin and electrospinning is a promising strategy for the preparation of tissue engineering scaffolds. In this review, the research progress of electrospun silk fibroin nanofibers in the regeneration of skin, vascular, bone, neural, tendons, cardiac, periodontal, ocular and other tissues is discussed in detail.

Recent Advances in Cellulose-Based Hydrogels: Food Applications

In the past couple of years, cellulose has attracted a significant amount of attention and research interest due to the fact that it is the most abundant and renewable source of hydrogels. With increasing environmental issues and an emerging demand, researchers around the world are focusing on naturally produced hydrogels in particular due to their biocompatibility, biodegradability, and abundance. Hydrogels are three-dimensional (3D) networks created by chemically or physically crosslinking linear (or branching) hydrophilic polymer molecules. Hydrogels have a high capacity to absorb water and biological fluids. Although hydrogels have been widely used in food applications, the majority of them are not biodegradable. Because of their functional characteristics, cellulose-based hydrogels (CBHs) are currently utilized as an important factor for different aspects in the food industry. Cellulose-based hydrogels have been extensively studied in the fields of food packaging, functional food, food safety, and drug delivery due to their structural interchangeability and stimuli-responsive properties. This article addresses the sources of CBHs, types of cellulose, and preparation methods of the hydrogel as well as the most recent developments and uses of cellulose-based hydrogels in the food processing sector. In addition, information regarding the improvement of edible and functional CBHs was discussed, along with potential research opportunities and possibilities. Finally, CBHs could be effectively used in the industry of food processing for the aforementioned reasons.

Alginate/polyvinyl alcohol films for wound healing: Advantages and challenges

The skin is the largest organ in the human body and its physical integrity must be maintained for body homeostasis and to prevent the entry of pathogenic microorganisms. Sodium alginate (SA) and polyvinyl alcohol (PVA) are two polymers widely used in films for wound dressing applications. Furthermore, blends between SA and PVA improve physical, mechanical and biological properties of the final wound healing material when compared to the individual polymers. Different drugs have been incorporated into SA/PVA-based films to improve wound healing activity. It is noteworthy that SA/PVA films can be crosslinked with Ca²⁺ or other agents, which improves physicochemical and biological properties. Thus, SA/PVA associations are promising for the biomedical field, as a potential alternative for wound treatment. This review focuses on the main techniques for obtaining SA/PVA films, their physical-chemical characterization, drug incorporation, and the advantages and challenges of these films for wound healing.

Novel strategies for designing regenerative skin products for accelerated wound healing

Healthy skin protects from pathogens, water loss, ultraviolet rays, and also maintains homeostasis conditions along with sensory perceptions in normal circumstances. Skin wound healing mechanism is a multi-phased biodynamic process that ultimately triggers intercellular and intracellular mechanisms. Failure to implement the normal and effective healing process may result in chronic injuries and aberrant scarring. Chronic wounds lead to substantial rising healthcare expenditure, and innovative methods to diagnose and control severe consequences are urgently needed. Skin tissue engineering (STE) has achieved several therapeutic accomplishments during the last few decades, demonstrating tremendous development. The engineered skin substitutes provide instant coverage for extensive wounds and facilitate the prevention of microbial infections and fluid loss; furthermore, they help in fighting inflammation and allow rapid neo-tissue formation. The current review primarily focused on the wound recovery and restoration process and the current conditions of STE with various advancements and complexities associated with different strategies such as cell sources, biopolymers, innovative fabrication techniques, and growth factors delivery systems.

Polymeric biomaterials for wound healing applications: a comprehensive review

Chronic wounds have been a global health threat over the past few decades, requiring urgent medical and research attention. The factors delaying the wound-healing process include obesity, stress, microbial infection, aging, edema, inadequate nutrition, poor oxygenation, diabetes, and implant complications. Biomaterials are being developed and fabricated to accelerate the healing of chronic wounds, including hydrogels, nanofibrous, composite, foam, spongy, bilayered, and trilayered scaffolds. Some recent advances in biomaterials development for healing both chronic and acute wounds are extensively compiled here. In addition, various properties of biomaterials for wound-healing applications and how they affect their performance are reviewed. Based on the recent literature, trilayered constructs appear to be a convincing candidate for the healing of chronic wounds and complete skin regeneration because they mimic the full thickness of skin: epidermis, dermis, and the hypodermis. This type of scaffold provides a dense superficial layer, a bioactive middle layer, and a porous lower layer to aid the wound-healing process. The hydrophilicity of scaffolds aids cell attachment, cell proliferation, and protein adhesion. Other scaffold characteristics such as porosity, biodegradability, mechanical properties, and gas permeability help with cell accommodation, proliferation, migration, differentiation, and the release of bioactive factors.

A new versatile x-y-z electrospinning equipment for nanofiber synthesis in both far and near field

This work describes a versatile electrospinning equipment with rapid, independent, and precise x–y–z movements for large-area depositions of electrospun fibers, direct writing or assembly of fibers into sub-millimeter and micron-sized patterns, and printing of 3D micro- and nanostructures. Its versatility is demonstrated thought the preparation of multilayered functional nanofibers for wound healing, nanofiber mesh for particle filtration, high-aspect ratio printed lines, and freestanding aligned nanofibers.

Silk fibroin/polycaprolactone-polyvinyl alcohol directional moisture transport composite film loaded with antibacterial drug-loading microspheres for wound dressing materials

Drug delivery technology can prevent wound infection and inflammatory reactions and accelerate wound healing and quality. In this paper, we propose preparing a multifunctional medical dressing to meet the various needs of people for dressing. A multi-layered composite nanofiber membrane was constructed using silk fibroin as the substrate, and mesoporous silica nanoparticles (MSN) with high adsorption properties were first prepared and then electrosprayed on silk fibroin (SF)/chitosan (CS) microspheres to form MSN-SF/CS microspheres with uniform distribution. Then the MSN-SF/CS microspheres were sprayed on the silk fibroin (SF)/polycaprolactone (PCL)-polyvinyl alcohol (PVA) unidirectional water-conducting composite nanofiber membrane. The test results showed that the encapsulation rate of bovine serum albumin (BSA) by MSN-SF/CS drug-loaded microspheres was 65.53% and the cumulative release rate in vitro was 54.46%. The results of in vitro experiments also showed its good antibacterial effect and good biocompatibility. To eliminate excess wound exudate and reduce inflammation, the cumulative unidirectional transport capacity (AOTC) of 651.75% was achieved by spraying the microspheres on an SF/PCL- PVA unidirectional water conductive composite membrane. This study could stimulate and promote the use of additional wound healing biomaterials in clinical medicine.

An Overview of Cellulose Derivatives-Based Dressings for Wound-Healing Management

Presently, notwithstanding the progress regarding wound-healing management, the treatment of the majority of skin lesions still represents a serious challenge for biomedical and pharmaceutical industries. Thus, the attention of the researchers has turned to the development of novel materials based on cellulose derivatives. Cellulose derivatives are semi-synthetic biopolymers, which exhibit high solubility in water and represent an advantageous alternative to water-insoluble cellulose. These biopolymers possess excellent properties, such as biocompatibility, biodegradability, sustainability, non-toxicity, non-immunogenicity, thermo-gelling behavior, mechanical strength, abundance, low costs, antibacterial effect, and high hydrophilicity. They have an efficient ability to absorb and retain a large quantity of wound exudates in the interstitial sites of their networks and can maintain optimal local moisture. Cellulose derivatives also represent a proper scaffold to incorporate various bioactive agents with beneficial therapeutic effects on skin tissue restoration. Due to these suitable and versatile characteristics, cellulose derivatives are attractive and captivating materials for wound-healing applications. This review presents an extensive overview of recent research regarding promising cellulose derivatives-based materials for the development of multiple biomedical and pharmaceutical applications, such as wound dressings, drug delivery devices, and tissue engineering.