A novel cell support membrane for skin tissue engineering: Gelatin film cross-linked with 2-chloro-1-methylpyridinium iodide

Preparation and properties of chitosan/gelatin/supersaturated calcium citrate scaffolds crosslinked by dehydrogenation heat treatment method

Low cross-linking degree, weak mechanical strength, and poor osteoinductivity are significant obstacles in the development of bone repair materials. In this study, chitosan/gelatin/supersaturated calcium citrate scaffolds were prepared with the dehydrogenation heat treatment method. The results confirmed that citric acid significantly improved the cross-linking degree and efficiency of the chitosan/gelatin scaffolds. But the addition of Ca2+ reduced the cross-linking degree, water absorption, and resistance to enzymatic degradation of the scaffolds. While, the supersaturated calcium citrate formed inside the scaffold increased its mechanical strength. The biocompatibility and osteogenic activity of scaffolds were measured by inoculation with MC3T3-E1 cells. The rapid and efficient release of Ca2+ from the scaffolds could significantly promote cell adhesion, proliferation, and differentiation, while cell activities were inhibited by excessive Ca2+. The results of repairing skull defects in SD rats demonstrated that the chitosan/gelatin/supersaturated calcium citrate scaffolds with 25 mM Ca2+ added had a stronger osteogenic effect compared to the chitosan/gelatin scaffolds. Hence, the chitosan/gelatin/ supersaturated calcium citrate scaffolds prepared in this study are promising materials for treating bone defects. The appropriate amount of calcium salt added to the scaffold in order to optimize its biocompatibility and osteogenic activity deserves further investigation.

Trends in protein derived materials for wound care applications

Natural resource based polymers, especially those derived from proteins, have attracted significant attention for their potential utilization in advanced wound care applications. Protein based wound care materials provide superior biocompatibility, biodegradability, and other functionalities compared to conventional dressings. The effectiveness of various fabrication techniques, such as electrospinning, phase separation, self-assembly, and ball milling, is examined in the context of developing protein-based materials for wound healing. These methods produce a wide range of forms, including hydrogels, scaffolds, sponges, films, and bioinspired nanomaterials, each designed for specific types of wounds and different stages of healing. This review presents a comprehensive analysis of recent research that investigates the transformation of proteins into materials for wound healing applications. Our focus is on essential proteins, such as keratin, collagen, gelatin, silk, zein, and albumin, and we emphasize their distinct traits and roles in wound care management. Protein-based wound care materials show promising potential in biomedical engineering, offering improved healing capabilities and reduced risks of infection. It is crucial to explore the potential use of these materials in clinical settings while also addressing the challenges that may arise from their commercialization in the future.

Biopolymer hydrogels and synergistic blends for tailored wound healing

Biopolymers have a transformative role in wound repair due to their biocompatibility, ability to stimulate collagen production, and controlled drug and growth factor delivery. This article delves into the biological parameters critical to wound healing emphasizing how combinations of hydrogels with reparative properties can be strategically designed to create matrices that stimulate targeted cellular responses at the wound site to facilitate tissue repair and recovery. Beyond a detailed examination of various biopolymer types and their functionalities in wound dressings acknowledging that the optimal choice depends on the specific wound type and application, this evaluation provides concepts for developing synergistic biopolymer blends to create next-generation dressings with enhanced efficiencies. Furthermore, the incorporation of therapeutic agents such as medications and wound healing accelerators into dressings to enhance their efficacy is examined. These agents often possess desirable properties such as antibacterial activity, antioxidant effects, and the ability to promote collagen synthesis and tissue regeneration. Finally, recent advancements in conductive hydrogels are explored, highlighting their capabilities in treatment and real-time wound monitoring. This comprehensive resource emphasizes the importance of optimizing ingredient efficiency besides assisting researchers in selecting suitable materials for personalized wound dressings, ultimately leading to more sophisticated and effective wound management strategies.

Fabrication and Characterization of an Electro-Compacted Collagen/Elastin/Hyaluronic Acid Sheet as a Potential Skin Scaffold

The development of biomimetic structures with integrated extracellular matrix (ECM) components represents a promising approach to biomaterial fabrication. Here, an artificial ECM, comprising the structural protein collagen I and elastin (ELN), as well as the glycosaminoglycan hyaluronan (HA), is reported. Specifically, collagen and ELN are electrochemically aligned to mimic the compositional characteristics of the dermal matrix. HA is incorporated into the electro-compacted collagen-ELN matrices via adsorption and chemical immobilization, to give a final composition of collagen/ELN/HA of 7:2:1. This produces a final collagen/ELN/hyaluronic acid scaffold (CEH) that recapitulates the compositional feature of the native skin ECM. This study analyzes the effect of CEH composition on the cultivation of human dermal fibroblast cells (HDFs) and immortalized human keratinocytes (HaCaTs). It is shown that the CEH scaffold supports dermal regeneration by promoting HDFs proliferation, ECM deposition, and differentiation into myofibroblasts. The CEH scaffolds are also shown to support epidermis growth by supporting HaCaTs proliferation, differentiation, and stratification. A double-layered epidermal-dermal structure is constructed on the CEH scaffold, further demonstrating its ability in supporting skin cell function and skin regeneration.

Human epidermal keratinocytes and human dermal fibroblasts interactions seeded on gelatin hydrogel for future application in skin in vitro 3-dimensional model

Introduction: Plenty of biomaterials have been studied for their application in skin tissue engineering. Currently, gelatin-hydrogel is used to support three-dimensional (3D) skin in vitro models. However, mimicking the human body conditions and properties remains a challenge and gelatin-hydrogels have low mechanical properties and undergo rapid degradation rendering them not suitable for 3D in vitro cell culture. Nevertheless, changing the concentration of hydrogels could overcome this issue. Thus, we aim to investigate the potential of gelatin hydrogel with different concentrations crosslinked with genipin to promote human epidermal keratinocytes and human dermal fibroblasts culture to develop a 3D-in vitro skin model replacing animal models. Methods: Briefly, the composite gelatin hydrogels were fabricated using different concentrations as follows 3%, 5%, 8%, and 10% crosslinked with 0.1% genipin or non-crosslinked. Both physical and chemical properties were evaluated. Results and discussion: The crosslinked scaffolds showed better properties, including porosity and hydrophilicity, and genipin was found to enhance the physical properties. Furthermore, no alteration was prominent in both formulations of CL_GEL 5% and CL_GEL8% after genipin modification. The biocompatibility assays showed that all groups promoted cell attachment, cell viability, and cell migration except for the CL_GEL10% group. The CL_GEL5% and CL_GEL8% groups were selected to develop a bi-layer 3D-in vitro skin model. The immunohistochemistry (IHC) and hematoxylin and eosin staining (H&E) were performed on day 7, 14, and 21 to evaluate the reepithelization of the skin constructs. However, despite satisfactory biocompatibility properties, neither of the selected formulations, CL_GEL 5% and CL_GEL 8%, proved adequate for creating a bi-layer 3D in-vitro skin model. While this study provides valuable insights into the potential of gelatin hydrogels, further research is needed to address the challenges associated with their use in developing 3D skin models for testing and biomedical applications.

A Comprehensive Review of Cross-Linked Gels as Vehicles for Drug Delivery to Treat Central Nervous System Disorders

Gels are attractive candidates for drug delivery because they are easily producible while offering sustained and/or controlled drug release through various mechanisms by releasing the therapeutic agent at the site of action or absorption. Gels can be classified based on various characteristics including the nature of solvents used during preparation and the method of cross-linking. The development of novel gel systems for local or systemic drug delivery in a sustained, controlled, and targetable manner has been at the epitome of recent advances in drug delivery systems. Cross-linked gels can be modified by altering their polymer composition and content for pharmaceutical and biomedical applications. These modifications have resulted in the development of stimuli-responsive and functionalized dosage forms that offer many advantages for effective dosing of drugs for Central Nervous System (CNS) conditions. In this review, the literature concerning recent advances in cross-linked gels for drug delivery to the CNS are explored. Injectable and non-injectable formulations intended for the treatment of diseases of the CNS together with the impact of recent advances in cross-linked gels on studies involving CNS drug delivery are discussed.

Biomimetic nanoengineered scaffold for enhanced full-thickness cutaneous wound healing

Wound healing is a complex process based on the coordinated signaling molecules and dynamic interactions between the engineered scaffold and newly formed tissue. So far, most of the engineered scaffolds used for the healing of full-thickness skin wounds do not mimic the natural extracellular matrix (ECM) complexity and therefore are not able to provide an appropriate niche for endogenous tissue regeneration [1]. To address this gap and to accelerate the wound healing process, we present biomimetic bilayer scaffolds compositing of gelatin nanofibers (GFS) and photocrosslinkable composite hydrogels loaded with epidermal growth factors (EGF). The nanofibers operate as the dermis layer, and EGF-loaded composite hydrogels acted as the epidermis matrix for the full-thickness wound healing application. The hydrogels are composed of gelatin metacryloyl (GelMA) modified with silicate nanoplatelets (Laponite). To overcome the challenges of transdermal delivery of EGF, including short half-life and lack of efficient formulation precise, controlled delivery was attained by immobilization of EGF on Laponite. It is shown that the addition of 1wt% silicate nanoplatelet increases the compressive modulus of the hydrogels by 170%. In vitro wound closure analysis also demonstrated improved adhesion of the scaffolds to the native tissue by 3.5 folds. Moreover, the tunable hemostatic ability of the scaffolds due to the negatively charged nanoplatelets is shown. In an established excisional full-thickness wound model, an enhanced wound closure (up to 93.1 ± 1.5%) after 14 days relative to controls (GFS and saline-treated groups) is demonstrated. The engineered adhesive and hemostatic scaffolds with sustained release of the growth factors have the potential to stimulate complete skin regeneration for full-thickness wound healing.

Pharmaceutical evaluation of atorvastatin-loaded nanostructured lipid carriers incorporated into the gelatin/hyaluronic acid/polycaprolactone scaffold for the skin tissue engineering

In this study, gelatin/hyaluronic acid (HA) scaffolds containing different amounts of atorvastatin-loaded nanostructured lipid carriers (NLCs) coated entirely with polycaprolactone (PCL) film were fabricated for skin regeneration. 12 atorvastatin-loaded NLCs formulations were synthesized, and particle size, zeta potential, drug entrapment efficiency (EE), and drug release of the formulations were determined. The optimum freeze-dried atorvastatin-loaded NLCs were added in 3 different weight percentages to the gelatin and HA membranous scaffolds. Thereafter, the membranes were coated entirely by a thin layer of the PCL. They were characterized, and then mechanical properties, in vitro degradation and in vitro drug release were assessed. Moreover, human dermal fibroblasts (HDF) were cultured on the prepared nanocomposite scaffolds in order to investigate the cytotoxicity by the MTT assay after the first day, third day, and fifth day. Results revealed that the most favorable atorvastatin-loaded NLCs had 99.54 nm average particle size, -24.30 mV zeta potential, 97.98% EE, and 75.24% drug release within 237 hrs. Mechanical tests indicated that all the three scaffolds had approximately a 90 MPa elastic modulus which was more than two-fold of tensile modulus of normal human skin. The in vitro degradation test demonstrated that the membranes were degraded up to 98% after 5 days, and the scaffolds drug release efficiency (DRE) was in a range of 75-79% during those 5 days. The MTT assay results confirmed the cytocompatibility of the scaffolds. The scaffold containing 54.1 wt% NCLs was the optimum sample (S₃). Scanning Electron Microscopy (SEM) images of the latter one showed the uniform distribution of the NLCs with an average size of 150 nm, and the images of cultured HDF illustrated the good cell attachment. In conclusion, suitable physicochemical and biological properties of the novel gelatin/HA/PCL nanocomposite scaffold containing 54.1 wt% atorvastatin-loaded NLCs (S₃) can be a good candidate for skin regeneration.

Functional Biomaterials for Treatment of Chronic Wound

The increasing number of patients with chronic wounds caused by diseases, such as diabetes, malignant tumors, infections, and vasculopathy, has caused severe economic and social burdens. The main clinical treatments for chronic wounds include the systemic use of antibiotics, changing dressings frequently, operative debridement, and flap repair. These routine therapeutic strategies are characterized by a long course of treatment, substantial trauma, and high costs, and fail to produce satisfactory results. Biomaterial dressings targeting the different stages of the pathophysiology of chronic wounds have become an active research topic in recent years. In this review, after providing an overview of the epidemiology of chronic wounds, and the pathophysiological characteristics of chronic wounds, we highlight the functional biomaterials that can enhance chronic wound healing through debridement, anti-infection and antioxidant effects, immunoregulation, angiogenesis, and extracellular matrix remodeling. It is hoped that functional biomaterials will resolve the treatment dilemma for chronic wounds and improve patient quality of life.

Evaluation of a Novel Collagenous Matrix Membrane Cross-Linked with Catechins Catalyzed by Laccase: A Sustainable Biomass

Collagen, a sustainable and biodegradable biomass material, has many applications in different scope including application in food packaging. However, owing to its poor mechanical properties, this kind of application is limited. In this work, collagen was cross-linked with catechin under the incubation of laccase to improve the mechanical properties of collagen, and the cross-linked collagen exhibited properties of excellent antioxidant capacity and lower swelling ratio. Meanwhile, Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results provide evidence for changes in the structure of collagen after being cross-linked with the catechin. From the aspects of the thermal stability, tensile strength, elongation, antioxidant capacity, swelling, solubility, and morphological analysis, the cross-linked collagen has better physical properties in comparison with natural collagen. This indicates that the physical properties and antioxidant capacity of collagen after being cross-linked with catechins were improved significantly. Therefore, the cross-linked collagen can be used as green food-packaging materials.

Photocrosslinkable Gelatin Hydrogel for Epidermal Tissue Engineering

Natural hydrogels are promising scaffolds to engineer epidermis. Currently, natural hydrogels used to support epidermal regeneration are mainly collagen- or gelatin-based, which mimic the natural dermal extracellular matrix but often suffer from insufficient and uncontrollable mechanical and degradation properties. In this study, a photocrosslinkable gelatin (i.e., gelatin methacrylamide (GelMA)) with tunable mechanical, degradation, and biological properties is used to engineer the epidermis for skin tissue engineering applications. The results reveal that the mechanical and degradation properties of the developed hydrogels can be readily modified by varying the hydrogel concentration, with elastic and compressive moduli tuned from a few kPa to a few hundred kPa, and the degradation times varied from a few days to several months. Additionally, hydrogels of all concentrations displayed excellent cell viability (>90%) with increasing cell adhesion and proliferation corresponding to increases in hydrogel concentrations. Furthermore, the hydrogels are found to support keratinocyte growth, differentiation, and stratification into a reconstructed multilayered epidermis with adequate barrier functions. The robust and tunable properties of GelMA hydrogels suggest that the keratinocyte laden hydrogels can be used as epidermal substitutes, wound dressings, or substrates to construct various in vitro skin models.

Insights into the interactions between porcine collagen and a Zr–Al–Ti metal complex

Porcine acelluar dermal matrix (pADM), known as pure collagen with a three dimensional structure, was used to explore the interactions between porcine collagen and a metal complex in this study.

Tailoring the properties of gelatin films for drug delivery applications: influence of the chemical cross-linking method

Two types of chemically cross-linked gelatin films were prepared and characterized. The first type of films was cross-linked with 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride (EDC) under heterogeneous conditions and are named Gel-E. In the second type of films, gelatin was previously functionalized with methacrylamide side groups by the reaction with methacrylic anhydride and for that is named Gel-MA. The modified gelatin was subsequently cross-linked by a photoinitiated radical polymerization. These films were characterized relatively to their degree of cross-linking, buffer uptake capacity, resistance to hydrolytic and proteolytic degradation, and mechanical and thermal properties. Results show that the employed cross-linking method, together with the degree cross-linking, dictate the final properties of the films. Gel-E films have significant lower buffer uptake capacities and higher resistance to collagenase digestion when compared to Gel-MA films. Additionally, Gel-E films exhibit higher values of stress at break and lower strains at break. Moreover, the films properties could be modified by varying the extent of the chemical cross-linking, which in turn could be controlled by varying the concentration of EDC, for the first type of films (Gel-E), or by using gelatins with different degrees of functionalization, in the case of the second type of films (Gel-MA).

Development and performance characterization of a polyamide nanofiltration membrane modified with covalently bonded aramide dendrimers

A first generation of amine terminated aramide dendrimers (G1-NH2) was covalently attached to the polyamide (PA) active layer of a commercially available nanofiltration (NF) membrane. Amide bonds between G1-NH2 and PA free carboxylic groups were formed by activation of the carboxylic groups with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) or 2-chloro-1-methylpyridinium iodide (CMPI), followed by aminolysis. Dendrimer attachment was assessed by indirectly measuring the concentration of carboxylic groups and amine groups before and after membrane modification with RBS using yttrium and tungstate ions (Y(3+) and WO4(2-)) as ion probes. RBS analyses showed a decrease in the concentration of carboxylic groups and an increase in amine groups on the membrane active layer, consistent with dendrimers attaching covalently to the active layer. Permeation experiments with Rhodamine WT (R-WT) revealed that the water and solutes permeability decreased after modification with dendrimer G1-NH2. Water permeability of G1-NH2 modified membrane decreased by 16-19% using EDC combined with sulfo-N-hydroxysuccinimide (s-NHS), and by 17-33% using CMPI. The permeability of the electrolyte BaCl2 decreased by 54% after G1-NH2 modification using EDC/s-NHS and only by 20% using CMPI, the latter consistent with a weaker Donnan exclusion effect. The permeability of the larger solute R-WT decreased by 82% in modified G1-NH2 membranes when using EDC/s-NHS, and 64% for cross-linking reagent CMPI. Thus, the use of EDC/s-NHS was more favorable because it resulted in higher gains in solute rejection with lower losses in water permeability.