Fabrication of quaternary composite scaffold from silk fibroin, chitosan, gelatin, and alginate for skin regeneration

Silk-Based 3D Porous Scaffolds for Tissue Engineering

Silk fibroin, extracted from the silk of the Bombyx mori silkworm, stands out as a biomaterial due to its nontoxic nature, excellent biocompatibility, and adjustable biodegradability. Porous scaffolds, a type of biomaterial, are crucial for creating an optimal microenvironment that supports cell adhesion and proliferation, thereby playing an essential role in tissue remodeling and repair. Therefore, this review focuses on 3D porous silk fibroin-based scaffolds, first summarizing their preparation methods and then detailing their regenerative effects on bone, cartilage, tendon, vascular, neural, skin, hepatic, and tracheal epithelial tissue engineering in recent years.

Magnetic nanocomposite based on chitosan-gelatin hydrogel embedded with copper oxide nanoparticles: A novel and promising catalyst for the synthesis of polyhydroquinoline derivatives

Nanocatalysts are vital in several domains, such as chemical processes, energy generation, energy preservation, and environmental pollution mitigation. An experimental study was conducted at room temperature to evaluate the catalytic activity of the new gelatin-chitosan hydrogel/CuO/Fe3O4 nanocomposite in the asymmetric Hantzsch reaction. All components of the nanocomposite exhibit a synergistic effect as a Lewis acid, promote the reaction. Dimedone, ammonium acetate, ethyl acetoacetate, and other substituted aldehydes were used to synthesize diverse polyhydroquinoline derivatives. The nanocomposite exhibited exceptional efficacy (over 90 %) and durability (retaining 80 % of its original capacity after 5 cycles) as a catalyst in the one-pot asymmetric synthesis of polyhydroquinoline derivatives. Also, turnover numbers (TON) and turnover frequency (TOF) have been checked for catalyst (TON and TOF = 50,261 and 100,524 h-1) and products. The experiment demonstrated several benefits, such as exceptional product efficacy, rapid reaction time, functioning at ambient temperature without specific requirements, and effortless separation by the use of an external magnet after the reaction is finished. The results suggest the development of a magnetic nanocatalyst with exceptional performance. The composition of the Ge-CS hydrogel/CuO/Fe3O4 nanocomposite was thoroughly analyzed using several methods including FT-IR, XRD, FE-SEM, EDX, VSM, BET, and TGA. These analyses yielded useful information into the composition and characteristics of the nanocomposite, hence further enhancing the knowledge of its possible uses.

A novel multifunctional chitosan-gelatin/carboxymethyl cellulose-alginate bilayer hydrogel containing human placenta extract for accelerating full-thickness wound healing

The replication of skin's dermal and epidermal morphology within a full-thickness wound using a bi-layer hydrogel to cater to their distinct needs is a compelling pursuit. Moreover, human placenta extract (HPE), containing a diverse array of bioactive agents, has proven to be effective in promoting the wound healing process and enhancing epidermal keratinocytes. This study presents a multifunctional bi-layer hydrogel incorporating HPE for accelerating full-thickness wound healing through sustained HPE release, inhibition of bacteria invasion, and promotion of cell proliferation. The upper layer of the scaffold, known as the dressing layer, is composed of carboxymethyl cellulose and sodium alginate, serving as a supportive layer for cell proliferation. The under layer, referred to as the regenerative layer, is composed of chitosan and gelatin, providing an extracellular matrix-like, porous, moist, and antibacterial environment for cell growth. The scaffold was optimized to replicate the morphology of the dermal and epidermal layers, with suitable fibroblast infiltration and a pore size of approximately 283μm. Furthermore, the degradation rate of the samples matched the wound healing rate and persisted throughout this period. The sustained HPE release rate, facilitated by the degradation rate, was optimized to reach ~98% after 28 days, covering the entire healing period. The samples demonstrated robust antibacterial capabilities, with bacterial inhibition zone diameters of and 2.63±0.12cm for S. aureus and E. coli, respectively. The biocompatibility of the samples remained at approximately 68.33±4.5% after 21 days of fibroblast cell culture. The in vivo experiment indicated that the HPE@Bilayer hydrogel promotes the formation of new blood vessels and fibroblasts during the early stages of healing, leading to the appropriate formation of granulation tissue and a wound contraction rate of (79.31±3.1)%. Additionally, it resulted in the formation of a thick epidermal layer (keratinization) that effectively covered all the impaired areas, achieving a wound contraction rate of 95.83±6.3% at the late stage of wound healing. Furthermore, immunohistochemistry staining for CD31 and TGF-β revealed that the HPE@Bilayer group had 22 blood vessels/field and 34%-66% immunoactive cells, respectively, after 14 days of healing. However, by day 21, angiogenesis and TGF-β expression had declined, demonstrating that the wounds had been successfully treated with minimal scarring.

Formulation and Characterization of a Novel Oxidized Alginate-Gelatin-Silk Fibroin Bioink with the Aim of Skin Regeneration

Background

In the present study, a novel bioink was suggested based on the oxidized alginate (OAlg), gelatin (GL), and silk fibroin (SF) hydrogels.

Methods

The composition of the bioink was optimized by the rheological and printability measurements, and the extrusion-based 3D bioprinting process was performed by applying the optimum OAlg-based bioink.

Results

The results demonstrated that the viscosity of bioink was continuously decreased by increasing the SF/GL ratio, and the bioink displayed a maximum achievable printability (92 ± 2%) at 2% (w/v) of SF and 4% (w/v) of GL. Moreover, the cellular behavior of the scaffolds investigated by MTT assay and live/dead staining confirmed the biocompatibility of the prepared bioink.

Conclusion

The bioprinted OAlg-GL-SF scaffold could have the potential for using in skin tissue engineering applications, which needs further exploration.

Fabrication and evaluation of herbal beads to slow cell ageing

Several therapies and cosmetics are available commercially to prevent or delay cell ageing, which manifests as premature cell death and skin dullness. Use of herbal products such as Aloe vera, curcumin, vitamin C-enriched natural antioxidant, and anti-inflammatory biomolecules are potential ways to prevent or delay ageing. Eggshell membrane (ESM) is also a rich source of collagen; glycosaminoglycans (GAGs) also play an essential role in healing and preventing ageing. It is important to use an extended therapeutic process to prolong the effectiveness of these products, despite the fact that they all have significant anti-ageing properties and the ability to regenerate healthy cells. Encapsulated herbal components are therefore designed to overcome the challenge of ensuring continued treatment over time to prolong the effects of a bioactive component after in situ administration. To study their synergistic effects on a cellular level, alginate, Aloe vera, and orange peel extract were encapsulated in bio-polymeric foaming beads and modified with eggshell membrane protein (ESMP) at various concentrations (1 gm, 2 gm, and 5 gm): (A-Av-OP, A-Av-OP-ESMP1, ESMP2, and ESMP3). Analysis of the structural and functional properties of foaming beads showed interconnected 3D porous structure, a surface-functionalized group for entrapment of ESMP, and a significant reduction in pore size (51-35 m) and porosity (80%-60%). By performing DPPH assays, HRBC stabilization assays, and antibacterial tests, the beads were assessed as a natural anti-ageing product with sustained release of molecules effective against inflammatory response, oxidative stress, and microbial contamination. MTT assays were conducted using in vitro cell cultures to demonstrate cytocompatibility (in mouse 3T3 fibroblast cells) and cytotoxicity (in human carcinoma HeLa cells). Our study demonstrates that bio-polymeric ESMP beads up to 2 g (A-Av-OP-ESMP2) are practical and feasible natural remedies for suspending defective cell pathways, preventing cell ageing, and promoting healthy cell growth, resulting in a viable and practical natural remedy or therapeutic system.

Cell-Biomaterial Constructs for Wound Healing and Skin Regeneration

Over the years, conventional skin grafts, such as full-thickness, split-thickness, and pre-sterilized grafts from human or animal sources, have been at the forefront of skin wound care. However, these conventional grafts are associated with major challenges, including supply shortage, rejection by the immune system, and disease transmission following transplantation. Due to recent progress in nanotechnology and material sciences, advanced artificial skin grafts-based on the fundamental concepts of tissue engineering-are quickly evolving for wound healing and regeneration applications, mainly because they can be uniquely tailored to meet the requirements of specific injuries. Despite tremendous progress in tissue engineering, many challenges and uncertainties still face skin grafts in vivo, such as how to effectively coordinate the interaction between engineered biomaterials and the immune system to prevent graft rejection. Furthermore, in-depth studies on skin regeneration at the molecular level are lacking; as a consequence, the development of novel biomaterial-based systems that interact with the skin at the core level has also been slow. This review will discuss 1) the biological aspects of wound healing and skin regeneration, 2) important characteristics and functions of biomaterials for skin regeneration applications, and 3) synthesis and applications of common biomaterials for skin regeneration. Finally, the current challenges and future directions of biomaterial-based skin regeneration will be addressed.

Fabrication of a novel 3D scaffold for cartilage tissue repair: In-vitro and in-vivo study

Self-repairing is not an advanced ability of articular cartilage. Tissue engineering has provided a novel way for reconstructing cartilage using natural polymers because of their biocompatibility and bio-functionality. The purpose of cartilage tissue engineering is to design a scaffold with proper pore structure and similar biological and mechanical properties to the native tissue. In this study, porous scaffolds prepared from gelatin, chitosan and silk fibroin were blended with varying ratios. Between the blends of chitosan (C), gelatin (G) and silk fibroin (S), the scaffold with the weight per volume ratio of 2:2:3 (w/v) showed the most favorable and higher certain properties than the other blends. The CGS 2:2:3 scaffold showed the best pore size that is between 100 μm and 300 μm. The water absorption and degradation rate of the CGS 2:2:3 scaffold were found suitable for cartilage tissue engineering. Cell culture study using human chondrocytes showed good cell adhesion and proliferation. To further study the effect of this scaffold on the living tissue, 36 rabbits were randomly assigned to CGS 2:2:3 scaffold with and without seeded chondrocytes and control groups. Hematoxylin and Eosin (H&E), Masson's trichrome (MT), and safranin O (SO) staining showed 65 ± 9.1% new cartilage tissue present in the defect filled with cell-seeded scaffold and most of the cartilaginous tissue was hyaline cartilage, while the control group showed no new cartilage tissue.

Fabrication and Characterization of Chitosan-Tamarind Seed Polysaccharide Composite Film for Transdermal Delivery of Protein/Peptide

Transdermal drug delivery is used to deliver a drug by eliminating the first-pass metabolism, which increases the bioavailability of the drug. The present study aims to formulate the chitosan—tamarind seed polysaccharide composite films and evaluate for the delivery of protein/peptide molecules. Nine formulations were prepared and evaluated by using different parameters, such as physical appearance, folding endurance, thickness of film, surface pH, weight variation, drug content, surface morphology, percentage moisture intake and uptake, drug release kinetics, and drug permeability. The film weight variance was observed between 0.34 ± 0.002 to 0.47 ± 0.003 g. The drug level of the prepared films was found to be between 96 ± 1.21 and 98 ± 1.33μg. Their intake of moisture ranged between 2.83 ± 0.002 and 3.76 ± 0.001 (%). The moisture absorption of the films ranged from 5.33 ± 0.22 to 10.02 ± 0.61 (%). SEM images revealed a smooth film surface, while minor cracks were found in the film after permeation tests. During the first 4 days, drug release was between 13.75 ± 1.64% and 22.54 ± 1.34% and from day 5 to day 6, it was between 72.67 ± 2.13% and 78.33 ± 3.13%. Drug permeation during the first 4 days was 15.78 ± 1.23 %. Drug permeation (%) during the first 4 days was between 15.78 ± 1.23 and 22.49 ± 1.29 and from day 5 to day 6, it was between 71.49 ± 3.21 and 77.93 ± 3.20.

Alginate-gum acacia based sponges as potential wound dressings for exuding and bleeding wounds

The improper management of wound exudates can expose the wound to bacterial invasion, skin maceration etc. thereby resulting in prolonged wound healing. Biopolymers are characterized by hydrophilic functional groups which when employed for the development of wound dressings promote the wound dressings capability to absorb a high amount of wound exudates. Alginate-gum acacia sponges were prepared from a combination of biopolymers such as sodium alginate and gum acacia in varying amounts with carbopol via crosslinking with 1 and 2% CaCl₂. The prepared sponges were loaded with a combination of ampicillin and norfloxacin. In vitro antibacterial analysis revealed that the antibacterial activity of the loaded antibiotics was retained and the sponges were effective against gram-positive and gram-negative bacteria. The sponges displayed rapid and high absorption capability in the range of 1022-2419% at pH 5.5 simulating wound exudates, and 2268-5042% at pH 7.4 simulating blood within a period of 1-3 h. Furthermore, the whole blood clotting studies further revealed low absorbance values when compared to the control revealing the good clotting capability of the sponges. The unique features of the sponges revealed their potential application for the management of infected, high exuding and bleeding wounds.

Ternary nano-biocomposite films using synergistic combination of bacterial cellulose with chitosan and gelatin for tissue engineering applications

Ternary nano-biocomposite films of bacterial cellulose-chitosan-gelatin (BC-C-G) were fabricated by immersing the BC pellicles into chitosan and gelatin mixture and subsequently freeze-drying. Scanning electron microscopy (SEM) images of the nano-biocomposite films revealed the presence of interconnected pores, with fibre diameter 20-150 nm. The composite films have a porosity of 95.3%, and showed good hydrophilicity with swelling ratio of 19 ± 1.8 and in vitro degradability. X-ray diffraction, attenuated total reflectance Fourier transform infrared spectroscopy, and thermogravimetric (TG) analysis results showed some interactions among the molecules of BC, gelatin, and chitosan within the film. The composite film offered good matrix for adhesion and proliferation of L929 fibroblasts cells as indicated by the cell attachment study, FE-SEM of cell-film constructs and cytocompatibility assay. Thus, the nano-biocomposite films of BC-C-G could be of paramount importance as tissue engineering scaffold. The "all-natural" ternary polymer composite films of BC-C-G have not been evaluated before for biomedical applications.

Bacterial nanocellulose: Present status, biomedical applications and future perspectives

Bacterial nanocellulose (BNC) has emerged as a natural biopolymer of significant importance in diverse technological areas due to its incredible physicochemical and biological characteristics. However, the high capital investments, production cost and lack of well-organized scale-up processes resulting in low BNC production are the major impediments need to be resolved. This review enfolds the three different and important portions of BNC. Firstly, advancement in production technologies of BNC like cell-free extract technology, static intermittent fed batch technology and novel cost-effective substrates that might surmount the barriers associated with BNC production at industrial level. Secondly, as BNC and its composites (with other polymers/nanoparticles) represents the utmost material of preference in current regenerative and diagnostic medicine, therefore recently reported biomedical applications of BNC and functionalized BNC in drug delivery, tissue engineering, antimicrobial wound healing and biosensing are widely been focused here. The third and the most important aspect of this review is an in-depth discussion of various pitfalls associated with BNC production. Recent trends in BNC research to overcome the existing snags that might pave a way for industrial scale production of BNC thereby facilitating its feasible application in various fields are highlighted.

A Hierarchical Model To Understand the Processing of Polysaccharides/Protein-Based Films in Ionic Liquids

In recent years, biomaterials from abundant and renewable sources have shown potential in medicine and materials science alike. In this study, we combine theoretical modeling, molecular dynamics simulations, and several experimental techniques to understand the regeneration of cellulose/silk-, chitin/silk-, and chitosan/silk-based biocomposites after dissolution in ionic liquid and regeneration in water. We propose a novel theoretical model that correlates the composite's microscopic structure to its bulk properties. We rely on modeling non-cross-linked biopolymers that present layer-like structures such as β-sheets and we successfully predict structural, thermal, and mechanical properties of a mixture of these biomolecules. Our model and experiments show that the solubility of the pure substance in the chosen solvent can be used to modulate the amount of crystallinity of the biopolymer blend, as measured by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Thermogravimetric analysis (TGA) shows that the decomposition temperature of the blended biocomposites compared to their pure counterparts is reduced in accordance with our theoretical predictions. The morphology of the material is further characterized through scanning electron microscopy (SEM) and shows differently exposed surface area depending on the blend. Finally, differential scanning calorimetry (DSC) is performed to characterize the residual water content in the material, essential for explaining the regeneration process in water. As a final test of the model, we compare our model's prediction of the Young's modulus with existing data in the literature. The model correctly reproduces experimental trends observed in the Young's modulus due to varying the concentration of silk in the biopolymer blend.

Tissue Regeneration: A Silk Road

Silk proteins are natural biopolymers that have extensive structural possibilities for chemical and mechanical modifications to facilitate novel properties, functions, and applications in the biomedical field. The versatile processability of silk fibroins (SF) into different forms such as gels, films, foams, membranes, scaffolds, and nanofibers makes it appealing in a variety of applications that require mechanically superior, biocompatible, biodegradable, and functionalizable biomaterials. There is no doubt that nature is the world's best biological engineer, with simple, exquisite but powerful designs that have inspired novel technologies. By understanding the surface interaction of silk materials with living cells, unique characteristics can be implemented through structural modifications, such as controllable wettability, high-strength adhesiveness, and reflectivity properties, suggesting its potential suitability for surgical, optical, and other biomedical applications. All of the interesting features of SF, such as tunable biodegradation, anti-bacterial properties, and mechanical properties combined with potential self-healing modifications, make it ideal for future tissue engineering applications. In this review, we first demonstrate the current understanding of the structures and mechanical properties of SF and the various functionalizations of SF matrices through chemical and physical manipulations. Then the diverse applications of SF architectures and scaffolds for different regenerative medicine will be discussed in detail, including their current applications in bone, eye, nerve, skin, tendon, ligament, and cartilage regeneration.