Gelatin Hydrogel Research Articles

Sustained-release, antibacterial, adhesive gelatin composite hydrogel with AgNPs double-capped with curdlan derivatives

In this work, carboxymethylated curdlan (CMCD) was utilized as a capping and stabilizing agent for the green synthesis of silver nanoparticles. Subsequently, quaternized curdlan (QCD) was introduced as the second capping layer through electrostatic attraction, leading to the preparation of double-capped silver nanoparticles (AgNPs@CQ). The successful synthesis of silver nanoparticles was characterized using UV–vis, FTIR, XRD, TEM, and DLS. AgNPs@CQ were incorporated into gelatin and a AgNPs@CQ/Gel composite hydrogel was obtained. The incorporation of AgNPs@CQ imparts excellent antibacterial properties to the composite hydrogel, thereby enhancing its antimicrobial efficacy. The presence of double-capping layers significantly retards the release rate of silver, contributing to prolonged antimicrobial activity. The MTT and live/dead fluorescence staining results demonstrate that the gelatin hydrogel incorporating double-capped AgNPs exhibits enhanced cell viability compared to the one incorporating single-capped AgNPs. Additionally, the composite hydrogel exhibits remarkable mechanical strength and adhesive performance. The AgNPs@CQ/Gel composite hydrogel demonstrates a cost-effective and facile preparation, showing significant potential in the field of dressings.

Study the effect of different concentrations of polydopamine as a secure and bioactive crosslinker on dual crosslinking of oxidized alginate and gelatin wound dressings

Alginate hydrogels are commonly used in wound care due to their ability to maintain a moist environment, absorb fluids, and aid wound healing. However, their stability and mechanical properties can sometimes limit their effectiveness. This study explores a new approach by creating a dual network system of oxidized alginate and gelatin hydrogel crosslinked with polydopamine in a single step, with the goal of improving the mechanical properties of these hydrogels. The unique aspect of this research is the comprehensive examination of different polydopamine concentrations in dual crosslinking systems. First, alginate was modified with sodium periodate to create additional active groups on its backbone, and various polydopamine concentrations were then tested to assess their impact on the dual crosslinking network and hydrogel properties. The study involved a range of tests, including FTIR, H-NMR, SEM, gelation time, rheology, adhesion, antioxidant activity, swelling ratio, weight loss, drug release, and cell viability. The addition of polydopamine was found to enhance the crosslinking density (0.859 × 109 mol.cm−3). Additionally, the results indicated improvements in properties such as reduced weight loss, enhanced antioxidant and adhesive qualities, and better mechanical properties (2240 kPa). However, the optimal concentration of polydopamine must be determined to achieve the best properties for a wound dressing. Excessive polydopamine can increase the space between polymer chains, leading to a reduction in crosslinking density and storage modulus. Nevertheless, it can also increase the swelling ratio, degradation rate, pore size, porosity, antioxidant activity, and dopamine release. Therefore, identifying the optimal concentration for a functional hydrogel is crucial. Notably, the hydrogel containing 0.5 mg.mL−1 polydopamine exhibited outstanding cell viability (108 % on the third day), swelling capacity (480 %), storage modulus (2240 kPa), gelation time (3 min), antioxidant activity (42.27 %), and skin adherence (11 kPa), making it an optimal choice for advanced wound management. According to the findings, it is emphasized that the application of this particular hydrogel expedites wound healing, as indicated by wound closure and histological studies. AbbreviationsUnlabelled TableOALoxidized alginateGELgelatinPDApolydopamineEDCsodium meta periodate 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochlorideNHSN-hydroxysuccinimide

Biohybrids for Combined Therapies of Skin Wounds: Agglomerates of Mesenchymal Stem Cells with Gelatin Hydrogel Beads Delivering Phages and Basic Fibroblast Growth Factor.

There is great interest in developing effective therapies for the treatment of skin wounds accompanied by deep tissue losses and severe infections. We have attempted to prepare biohybrids formed of agglomerates of mesenchymal stem cells (MSCs) with gelatin hydrogel beads (GEL beads) delivering bacteriophages (phages) as antibacterial agents and/or basic fibroblast growth factor (bFGF) for faster and better healing, providing combined therapies for these types of skin wounds. The gelatin beads were produced through a two-step process using basic and/or acidic gelatins with different isoelectric points. Escherichia coli (E. coli) and its specific T4 phages were propagated. Phages and/or bFGF were loaded within the GELs and their release rates and modes were obtained. The phage release from the basic GEL beads was quite fast; in contrast, the bFGF release from the acidic GEL beads was sustained, as anticipated. MSCs were isolated from mouse adipose tissues and 2D-cultured. Agglomerates of these MSCs with GEL beads were formed and maturated in 3D cultures, and their time-dependent changes were followed. In these 3D culture experiments, it was observed that the agglomerates with GEL beads were very healthy and the MSCs formed tissue-like structures in 7 days, while the MSC agglomerates were not healthy and shrunk considerably as a result of cell death.

Rheological Properties of Fish and Mammalian Gelatin Hydrogels as Bases for Potential Practical Formulations.

Hydrogels have the ability to retain large amounts of water within their three-dimensional polymer matrices. These attractive materials are used in medicine and the food industry; they can serve as the basis for structured food products, additives, and various ingredients. Gelatin is one of widely used biopolymers to create hydrogels that exhibit biocompatibility and tunable rheological properties. In this study, we offer a comparative analysis of rheological properties of gelatin-based hydrogels (C = 6.67%), including mammalian gelatins from bovine and porcine skins and fish gelatins from commercial samples and samples extracted from Atlantic cod skin. Mammalian gelatins provide high strength and elasticity to hydrogels. Their melting point lies in the range from 22 to 34 °C. Fish gelatin from cod skin also provides a high strength to hydrogels. Commercial fish gelatin forms weak gels exhibiting low viscoelastic properties and strength, as well as low thermal stability with a melting point of 7 °C. Gelatins were characterized basing on the analysis of amino acid composition, molecular weight distribution, and biopolymer secondary structure in gels. Our research provides a unique rheological comparison of mammalian and fish gelatin hydrogels as a tool for the re-evaluation of fish skin gelatin produced through circular processes.

Bio-inspired stretchable and self-healable nanocomposite gelatin hydrogel with low silica nanoparticle content and brilliant angle/strain-independent structural colors

Stretchable and self-healable structural-colored nanocomposite gelatin hydrogel with photonic structure of random dense/loose regions of non-close-packed silica nanoparticles (SiO2 NPs) is developed via convenient and scalable polymer-mediated assembly. The formation of the special photonic structure with overall low SiO2 NP content is characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The small-angle X-ray scattering test indicates the existence of short-range order, which is consistent with the TEM and SEM results. The dense photonic structure consisting of SiO2 NP chains and domains, and the loose structure consisting of abundant solitary SiO2 NPs, accounts for pronounced and uniform structural colors via combined effects of coherent scattering of light by dense structure, and Mie scattering of solitary NPs. These structural colors are independent of viewing angles and large mechanical strains. The dynamic physical and chemical bonding of the gelatin hydrogel network matrix enables self-healing functions and good deformability. Moreover, salt treatment of the structural-colored gelatin hydrogel networks enhances physical crosslinking and the mechanical strength of the hydrogel. The resilient, flexible and self-healable structural-colored nanocomposite hydrogel with low SiO2 NP content has great potential in wearable photonics, cosmetics, and various other color-related fields. This work also sheds light on enhancing non-iridescent structural colors through advanced photonic design.

Phage embedded gelatin, alginate and gelatin/alginate-starch based hydrogels for topical bactericidal applications against multi-drug resistant Pseudomonas aeruginosa

Topical phage administration through hydrogels is one of the most efficient ways to inhibit bacterial growth in soft tissues. Hydrogels can benefit the skin by acting as a barrier and also promote tissue regeneration and moisture retention in cases of skin breach. Hydrogels incorporated with bioactive ingredients (BAC) have found their way into skin applications ranging from pharmaceutical to cosmetic products, whereas, phage incorporated hydrogels have been under-explored. In this study, we developed gelatin (protein-based) and alginate (polysaccharide-based) hydrogels (GH & AH) to immobilize phages for topical antibacterial treatments. P. aeruginosa is a common wound infecting pathogen and the strain ATCC 15442 used in this study is a β-lactamase producing multi-drug resistant variant. Gelatin and alginate are natural polymers and were chemically crosslinked (covalent & ionic interactions) to develop matrices that embed phages. Aloe vera extracts were used to synthesize hydrogels to succor the healing process. Starch-incorporated gelatin and alginate gels were also screened for phage immobilization. The addition of starch adversely affected the porosity of the matrices but did not affect the swelling ratio of the hydrogels. SEM analysis revealed porous microstructure of gelatin and alginate hydrogel, where starch addition resulted in cracked surface topography. All the developed hydrogels were amorphous in nature, lacking a regular pattern in the structural orientation of the molecules. Phages were successfully administered into the matrix after hydrogel synthesis through absorption. The swelling ratio of gelatin and alginate hydrogels were 2.6 and 0.5 g/g at 30 min. Phages released in buffer at 30 min were 1.6 x 107 and 2.6 x 106 PFU/mL for gelatin and alginate hydrogels respectively. The antibacterial evaluation of phage-incorporated gels showed a zone of inhibition against phage specific P. aeruginosa in agar plates.

Acquired Temozolomide Resistance Instructs Patterns of Glioblastoma Behavior in Gelatin Hydrogels.

Acquired drug resistance in glioblastoma (GBM) presents a major clinical challenge and is a key factor contributing to abysmal prognosis, with less than 15 months median overall survival. Aggressive chemotherapy with the frontline therapeutic, temozolomide (TMZ), ultimately fails to kill residual highly invasive tumor cells after surgical resection and radiotherapy. Here, a 3D engineered model of acquired TMZ resistance is reported using two isogenically matched sets of GBM cell lines encapsulated in gelatin methacrylol hydrogels. Response of TMZ-resistant versus TMZ-sensitive GBM cell lines within the gelatin-based extracellular matrix platform is benchmarked and drug response at physiologically relevant TMZ concentrations is further validated. The changes in drug sensitivity, cell invasion, and matrix-remodeling cytokine production are shown as the result of acquired TMZ resistance. This platform lays the foundation for future investigations targeting key elements of the GBM tumor microenvironment to combat GBM's devastating impact by advancing the understanding of GBM progression and treatment response to guide the development of novel treatment strategies.

Advanced Methacrylated Gelatin (GelMA) Hydrogel Scaffolds for Wound Care Applications

Advanced Methacrylated Gelatin (GelMA) Hydrogel Scaffolds for Wound Care Applications

Expression, characterization, and application of human-like recombinant gelatin

Gelatin is a product obtained through partial hydrolysis and thermal denaturation of collagen, belonging to natural biopeptides. With irreplaceable biological functions in the field of biomedical science and tissue engineering, it has been widely applied. The amino acid sequence of recombinant human-like gelatin was constructed through a newly designed hexamer composed of six protein monomer sequences in series, with the minimum repeating unit being the characteristic Gly-X-Y sequence found in type III human collagen α1 chain. The nucleotide sequence was subsequently inserted into the genome of Pichia pastoris to enable soluble secretion expression of recombinant gelatin. At the shake flask fermentation level, the yield of recombinant gelatin is up to 0.057 g/L, and its purity can rise up to 95% through affinity purification. It was confirmed in the molecular weight determination and amino acid analysis that the amino acid composition of the obtained recombinant gelatin is identical to that of the theoretically designed. Furthermore, scanning electron microscopy revealed that the freeze-dried recombinant gelatin hydrogel exhibited a porous structure. After culturing cells continuously within these gelatin microspheres for two days followed by fluorescence staining and observation through confocal laser scanning microscopy, it was observed that cells clustered together within the gelatin matrix, exhibiting three-dimensional growth characteristics while maintaining good viability. This research presents promising prospects for developing recombinant gelatin as a biomedical material.

3D-Printed Hydrogels as Photothermal Actuators.

Thermoresponsive hydrogels were 3D-printed with embedded gold nanorods (GNRs), which enable shape change through photothermal heating. GNRs were functionalized with bovine serum albumin and mixed with a photosensitizer and poly(N-isopropylacrylamide) (PNIPAAm) macromer, forming an ink for 3D printing by direct ink writing. A macromer-based approach was chosen to provide good microstructural homogeneity and optical transparency of the unloaded hydrogel in its swollen state. The ink was printed into an acetylated gelatin hydrogel support matrix to prevent the spreading of the low-viscosity ink and provide mechanical stability during printing and concurrent photocrosslinking. Acetylated gelatin hydrogel was introduced because it allows for melting and removal of the support structure below the transition temperature of the crosslinked PNIPAAm structure. Convective and photothermal heating were compared, which both triggered the phase transition of PNIPAAm and induced reversible shrinkage of the hydrogel-GNR composite for a range of GNR loadings. During reswelling after photothermal heating, some structures formed an internally buckled state, where minor mechanical agitation recovered the unbuckled structure. The BSA-GNRs did not leach out of the structure during multiple cycles of shrinkage and reswelling. This work demonstrates the promise of 3D-printed, photoresponsive structures as hydrogel actuators.

FRESH-based 3D bioprinting of complex biological geometries using chitosan bioink

Traditional three-dimensional (3D) bioprinting has always been associated with the challenge of print fidelity of complex geometries due to the gel-like nature of the bioinks. Embedded 3D bioprinting has emerged as a potential solution to print complex geometries using proteins and polysaccharides-based bioinks. This study demonstrated the Freeform Reversible Embedding of Suspended Hydrogels (FRESH) 3D bioprinting method of chitosan bioink to 3D bioprint complex geometries. 4.5% chitosan was dissolved in an alkali solvent to prepare the bioink. Rheological evaluation of the bioink described its shear-thinning nature. The power law equation was fitted to the shear rate-viscosity plot. The flow index value was found to be less than 1, categorizing the material as pseudo-plastic. The chitosan bioink was extruded into another medium, a thermo-responsive 4.5% gelatin hydrogel. This hydrogel supports the growing print structures while printing. After this, the 3D bioprinted structure was crosslinked with hot water to stabilize the structure. Using this method, we have 3D bioprinted complex biological structures like the human tri-leaflet heart valve, a section of a human right coronary arterial tree, a scale-down outer structure of the human kidney, and a human ear. Additionally, we have shown the mechanical tunability and suturability of the 3D bioprinted structures. This study demonstrates the capability of the chitosan bioink and FRESH method for 3D bioprinting of complex biological models for biomedical applications.

Mechanisms of Degradation of Collagen or Gelatin Materials (Hemostatic Sponges) in Oral Surgery: A Systematic Review

Objective: The goal of this systematic review was to identify the mechanisms associated with the enzymatic degradation of collagen and gelatin biomaterials and the possible associated flaws. Methods: Four databases (PubMed, B-On, Cochrane Library, and ResearchGate) were used for the bibliographic search of articles. The research question was formulated using the PCC method, (P): collagen or gelatin sponges, hydrogels, and scaffolds; concept (C): enzymatic degradation of collagen or gelatin sponges, hydrogels, and scaffolds; and context (C): effect of enzymatic action on degradation time of collagen or gelatin sponges, hydrogels, and scaffolds. The search was contextualized according to PRISMA recommendations. The identification and exclusion of evidence followed the PRISMA criteria, with specific inclusion and exclusion factors being stipulated for the selection of articles. The risk of bias assessment was performed using the QUIN Scale. Results: The initial search was composed of 13,830 articles after removing duplicates; 56 articles followed for the full-text reading; 45 were excluded; then, 11 articles were obtained, constituting the results of this systematic review. All studies evaluated the materials using gravimetric analysis, and collagenases were the proteases used for the degradation solution. The materials tested were as follows: human-like collagen (HLC) hydrogel with microbial transglutaminase (MTGase), gelatin sponges subjected to different types of crosslinking, and collagen scaffolds with different types of crosslinking. The period of analysis varied between 0.25 h and 35 days. It was possible to highlight the lack of uniformity in the protocols used, which varied largely, thus influencing the degradation times. The risk of bias was low in nine studies and medium in two studies. Conclusions: This systematic review identified a gap in the literature, highlighting the absence of in vitro studies using human saliva and a collagenase concentration close to the physiological levels to simulate oral dynamics. However, based on existing literature, the mechanisms associated with collagen enzymatic degradation in collagen and gelatin biomaterials were comprehensively understood, answering the first research question postulated. In response to the second research question, the main shortcomings identified in the laboratory evaluation of mechanisms associated with collagen enzymatic degradation in collagen and gelatin biomaterials included the lack of standardization in degradation test protocols; this limited inter-study comparisons, which increased heterogeneity. Additionally, variations in collagenase concentrations and types influenced collagen degradation rates, and inappropriate evaluation intervals hindered the identification of total degradation time.

Characterization of gelatin-oxidized riclin cryogels and their applications as reusable ice cubes in shrimp preservation

Traditional ice is usually employed to preserve food freshness and extend shelf life. However, ice cannot bear repeated freeze − thaw cycles during the transportation and retailing process, resulting in microbial cross-contamination and spoilage of foods. Herein, succinoglycan riclin was oxidated (RO) and crosslinked with gelatin (Ge), the Ge-RO cryogels were prepared via Schiff base reaction and three freeze − thaw cycles. The Ge-RO cryogels showed improved storage modulus (G′) and thermal stability compared with pure gelatin hydrogel. The polymer framework of Ge-RO gels exhibited stable properties against ice crystals destructions during nine freeze − thaw treatments. During the storage and repeated freeze − thaw treatments of shrimps, Ge-RO cryogels exhibited a remarkable preservation effect on shrimps, and their freshness was evaluated using an electronic nose technique equipped with ten sensors. The results demonstrated that the shrimp muscle preserved in ice generated off-odors and resulted in high sensor responses. The sensor responses were reduced sharply of shrimps preserved in cryogels. Moreover, 1H NMR-based metabolomics analysis revealed that shrimps in Ge-RO cryogels group reversed the metabolic perturbations compared with the traditional ice group, the metabolic pathways were related to energy metabolism, nucleotide metabolism, and amino acid metabolism, which provide new clues to the freshness of shrimps. Furthermore, RO exhibited superior antimicrobial activity against E. coli and S. aureus microorganisms. Thus, the crosslinked cryogels are potentially applicable to food preservation, offering sustainable and reusable solutions against traditional ice.

Enhanced hepatotoxicity assessment through encapsulated HepG2 spheroids in gelatin hydrogel matrices: Bridging the gap from 2D to 3D culture

Conventional 2D drug screening often fails to accurately predict clinical outcomes. We present an innovative approach to improve hepatotoxicity assessment by encapsulating HepG2 spheroids in gelatin hydrogel matrices with different mechanical properties. Encapsulated spheroids exhibit sustained liver-specific functionality, enhanced expression of drug-metabolizing enzymes, and increased drug sensitivity compared to 2D cultures. The platform detects critical variations in drug response, with significant differences in IC50 values between 2D and spheroid cultures ranging from 1.3-fold to > 13-fold, particularly for acetaminophen. Furthermore, drug-metabolizing enzyme expression varies across hydrogel concentrations, suggesting a role for matrix mechanical properties in modulating hepatocyte function. This novel spheroid-hydrogel platform offers a transformative approach to hepatotoxicity assessment, providing increased sensitivity, improved prediction, and a more physiologically relevant environment. The use of such advanced in vitro models can accelerate drug development, reduce animal testing, and contribute to improved patient safety and clinical outcomes.

The hyaluronic acid-gelatin hierarchical hydrogel for osteoporotic bone defect repairment

Osteoporotic bone defects are serious medical problems due to their sparse bone structure, difficulty in restoration and reconstruction, and high recurrence rates, which also result in heavy economic and social burdens. Herein, we developed a hierarchical hydrogel composed of alendronate sodium (AS)/Mg2+-loaded inverse opal methylpropenylated gelatin (GelMA) hydrogel microspheres (IOHM-AS-Mgs) within methylpropenylated poly(hyaluronic acid) (HAMA) for osteoporotic bone defect treatment. The IOHM-AS-Mgs displayed good cytocompatibility and cell adhesion and strongly stimulated osteogenesis at the transcriptomic and protein levels. When this treatment was applied to the osteoporotic bone defect area, HAMA was used to fix the microspheres. The results of the microcomputed tomography (micro-CT) and histological analyses indicated that the hierarchical hydrogel had the best therapeutic effect. Therefore, this hydrogel is a new candidate for osteoporotic bone defect treatment.

Mesenchymal Stem Cell-Loaded Hydrogel Improves Surgical Treatment for Chronic Cerebral Ischemia.

Chronic cerebral ischemia (CCI) results in a prolonged insufficient blood supply to the brain tissue, leading to impaired neuronal function and subsequent impairment of cognitive and motor abilities. Our previous research showed that in mice with bilateral carotid artery stenosis, the collateral neovascularization post Encephalo-myo-synangiosis (EMS) treatment could be facilitated by bone marrow mesenchymal stem cells (MSCs) transplantation. Considering the advantages of biomaterials, we synthesized and modified a gelatin hydrogel for MSCs encapsulation. We then applied this hydrogel on the brain surface during EMS operation in rats with CCI, and evaluated its impact on cognitive performance and collateral circulation. Consequently, MSCs encapsulated in hydrogel significantly augment the therapeutic effects of EMS, potentially by promoting neovascularization, facilitating neuronal differentiation, and suppressing neuroinflammation. Furthermore, taking advantage of multi-RNA-sequencing and in silico analysis, we revealed that MSCs loaded in hydrogel regulate PDCD4 and CASP2 through the overexpression of miR-183-5p and miR-96-5p, thereby downregulating the expression of apoptosis-related proteins and inhibiting early apoptosis. In conclusion, a gelatin hydrogel to enhance the functionality of MSCs has been developed, and its combination with EMS treatment can improve the therapeutic effect in rats with CCI, suggesting its potential clinical benefit.

Application of 3D bioprinting technology apply to assessing Dangguiniantongtang (DGNT) decoctions in arthritis

The aim of this study was to develop a three-dimensional (3D) cell model in order to evaluate the effectiveness of a traditional Chinese medicine decoction in the treatment of arthritis. Chondrocytes (ATDC5) and osteoblasts (MC3T3-E1) were 3D printed separately using methacryloyl gelatin (GelMA) hydrogel bioinks to mimic the natural 3D cell environment. Both cell types showed good biocompatibility in GelMA. Lipopolysaccharide (LPS) was added to the cell models to create inflammation models, which resulted in increased expression of inflammatory factors IL-1β, TNF-α, iNOS, and IL-6, and decreased expression of cell functional genes such as Collagen II (COLII), transcription factor SOX-9 (Sox9), Aggrecan, alkaline phosphatase (ALP), RUNX family transcription factor 2 (Runx2), Collagen I (COLI), Osteopontin (OPN), and bone morphogenetic protein-2 (BMP-2). The created inflammation model was then used to evaluate the effectiveness of Dangguiniantongtang (DGNT) decoctions. The results showed that DGNT reduced the expression of inflammatory factors and increased the expression of functional genes in the cell model. In summary, this study established a 3D cell model to assess the effectiveness of traditional Chinese medicine (TCM) decoctions, characterized the gene expression profile of the inflammatory state model, and provided a practical reference for future research on TCM efficacy evaluation for arthritis treatment.

Injective hydrogel loaded with liposomes-encapsulated MY-1 promotes wound healing and increases tensile strength by accelerating fibroblast migration via the PI3K/AKT-Rac1 signaling pathway

Failed skin wound healing, through delayed wound healing or wound dehiscence, is a global public health issue that imposes significant burdens on individuals and society. Although the application of growth factor is an effective method to improve the pace and quality of wound healing, the clinically approved factors are limited. Parathyroid hormone (PTH) demonstrates promising results in wound healing by promoting collagen deposition and cell migration, but its application is limited by potentially inhibitory effects when administered continuously and locally. Through partially replacing and repeating the amino acid domains of PTH(1–34), we previously designed a novel PTH analog, PTH(3–34)(29–34) or MY-1, and found that it avoided the inhibitory effects of PTH while retaining its positive functions. To evaluate its role in wound healing, MY-1 was encapsulated in liposomes and incorporated into the methacryloyl gelatin (GelMA) hydrogel, through which an injectable nanocomposite hydrogel (GelMA–MY@Lipo, or GML) was developed. In vitro studies revealed that the GML had similar properties in terms of the appearance, microstructure, functional groups, swelling, and degradation capacities as the GelMA hydrogel. In vitro drug release testing showed a relatively more sustainable release of MY-1, which was still detectable in vivo 9 days post-application. When the GML was topically applied to the wound areas of rat models, wound closure as well as tensile strength were improved. Further studies showed that the effects of GML on wound repair and tensile strength were closely related to the promotion of fibroblast migration to the wound area through the controlled release of MY-1. Mechanically, MY-1 enhanced fibroblast migration by activating PI3K/AKT signaling and its downstream molecule, Rac1, by which it increased fibroblast aggregation in the early stage and resulting in denser collagen deposition at a later time. Overall, these findings demonstrated that the nanocomposite hydrogel system promoted skin wound healing and increased tensile strength, thus offering new potential in the treatment of wound healing.

Physically Crosslinked Poly(methacrylic acid)/Gelatin Hydrogels with Excellent Fatigue Resistance and Shape Memory Properties.

Hydrogels endure various dynamic stresses, demanding robust mechanical properties. Despite significant advancements, matching hydrogels' strength to biological tissues and plastics is often challenging without applying potentially harmful crosslinkers. Using hydrogen bonds as sacrificial bonds offers a promising strategy to produce tough, versatile hydrogels for biomedical and industrial applications. Poly(methacrylic acid) (PMA)/gelatin hydrogels were synthesized by thermally induced free-radical polymerization and crosslinked only by physical bonds, without adding any chemical crosslinker. The addition of gelatin increased the formation of hydrophobic domains in the structure of the hydrogels, which acted as permanent crosslinking points. The increase in PMA and gelatin contents generally led to a lower equilibrium water content (WC), higher thermal stability and better mechanical properties. The values of tensile strength and toughness reached up to 1.44 ± 0.17 MPa and 4.91 ± 0.51 MJ m-3, respectively, while the compressive modulus and strength reached up to 0.75 ± 0.06 MPa and 24.81 ± 5.85 MPa, respectively, with the WC being higher than 50 wt.%. The obtained values for compressive mechanical properties are comparable with super-strong hydrogels reported in the literature. In addition, hydrogels exhibited excellent fatigue resistance and biocompatibility, as well as great shape memory properties, which make them prominent candidates for a wide range of biomedical applications.

Fabrication and characterization of magnetic graphene oxide-g-poly(acrylamide)/gelatin hydrogel nanocomposites for effective adsorption of copper ions from aqueous solutions

ABSTRACT In this work, a magnetic nanocomposite adsorbent was synthesized by crosslinking graft copolymerization of gelatin and acrylamide onto graphene oxide nanosheets in the presence of Fe3O4 nanoparticles. The structure of nanocomposites was characterized by using FTIR, SEM, TEM, XRD, VSM and point of zero charge (pHpzc). The prepared nanocomposites were employed as bioadsorbents for adsorption of copper ions. The effects of adsorption parameters under different conditions were studied in detail through batch experiments. The maximum ion adsorption capacity of 259 g. g−1 was achieved under the optimum conditions that were found to be: pH=8.0, copper concentration=80 mg L−1, adsorbent dosage=0.5 mg mg. L−1, contact time=2 hours, and temperature=60 °C. The kinetics and isotherms of adsorption fitted well at various ion concentrations (40, 80 and 160 mg L−1) using second-order and Langmuir models with R2=0.9991 and 0.9928, respectively. Moreover, the thermodynamic parameters show that the adsorption process was spontaneous and endothermic. In addition, the adsorbents depicted excellent regeneration ability after six adsorption-desorption cycles and maintained 89% of its initial adsorption capacity. In conclusion, the obtained results confirmed that the prepared environmentally friendly nanocomposites with high adsorption capacities could be effective adsorbents for the elimination of different ions from wastewaters.