Dual Chemotherapeutic Loading in Oxalate Transferrin-Conjugated Polymersomes Incorporated into Chitosan Hydrogels for Site-Specific Targeting of Melanoma Cells.

In this work, we developed a smart drug delivery system composed of poly (ethylene glycol)-block-poly (ε-caprolactone) (PEG-PCL)-based polymersomes (Ps) loaded with doxorubicin (DOX) and vemurafenib (VEM). To enhance targeted delivery to malignant melanoma cells, these drug-loaded nanovesicles were conjugated to the oxalate transferrin variant (oxalate Tf) and incorporated into three-dimensional chitosan hydrogels. This innovative approach represents the first application of oxalate Tf for the precision delivery of drug-loaded polymersomes within a semi-solid dosage form based on chitosan hydrogels. These resulting semi-solids exhibited a sustained release profile for both encapsulated drugs. To evaluate their potency, we compared the cytotoxicity of native Tf-Ps with oxalate Tf-Ps. Notably, the oxalate Tf-Ps demonstrated a 3-fold decrease in cell viability against melanoma cells compared to normal cells and were 1.6-fold more potent than native Tf-Ps, indicating the greater potency of this nanoformulation. These findings suggest that dual-drug delivery using an oxalate-Tf-targeting ligand significantly enhances the drug delivery efficiency of Tf-conjugated nanovesicles and offers a promising strategy to overcome the challenge of multidrug resistance in melanoma therapy.

Rheological Characterization of Genipin-Based Crosslinking Pigment and O-Carboxymethyl Chitosan-Oxidized Hyaluronic Acid In Situ Formulable Hydrogels.

The aim of this study was to develop a material capable of rapidly absorbing bodily fluids and forming a resilient, adhesive, viscoelastic hydrogel in situ to prevent post-surgical adhesions. This material was formulated using O-carboxymethyl chitosan (O-CMCS), oxidized hyaluronic acid (OHA), and a crosslinking pigment derived from genipin and glutamic acid (G/GluP). Both crosslinked (O-CMCS/OHA-G/GluP) and non-crosslinked hydrogels (O-CMCS/OHA) were evaluated using a HAAKE™ MARS™ rheometer for their potential as post-surgical barriers. A rheological analysis, including dynamic oscillatory measurements, revealed that the crosslinked hydrogels exhibited significantly higher elastic moduli (G'), indicating superior gel formation and mechanical stability compared to non-crosslinked hydrogels. The G/GluP crosslinker enhanced gel stability by increasing the separation between G' and G″ and achieving a lower loss tangent (tan δ < 1.0), indicating robustness under dynamic physiological conditions. The rapid hydration and gelation properties of the hydrogels underscore their effectiveness as physical barriers. Furthermore, the O-CMCS/OHA-G/GluP hydrogel demonstrated rapid self-healing and efficient application via spraying or spreading, with tissue adherence and viscoelasticity to facilitate movement between tissues and organs, effectively preventing adhesions. Additionally, the hydrogel proved to be both cost effective and scalable, highlighting its potential for clinical applications aimed at preventing post-surgical adhesions.

Fipronil-infused sodium polyacrylate gels provide effective management of Argentine ants in conservation areas.

BACKGROUND: Various types of hydrogel compounds have recently been developed for controlling invasive and pest ants in a range of environmental settings including agricultural, urban and natural areas. The current study evaluated the potential of sodium polyacrylate (ACR) hydrogels to effectively deliver liquid baits to Argentine ants. RESULTS: Relative to standard polyacrylamide (PAM) hydrogels, individual ACR hydrogel particles were approximately five-fold heavier; this may affect how ants interact with the bait particles, and further influence bait uptake and efficacy. Additionally, ACR hydrogels had significantly higher water absorption capacity and significantly slower rate of water loss, especially during the first 2 h. The efficacy of ACR hydrogel bait containing 0.005% fipronil and various attractants was evaluated on laboratory colonies. Results demonstrated that ACR hydrogel acceptance is significantly increased by the addition of feeding attractants. In addition, a field trial was performed in a nature reserve invaded by Argentine ants to evaluate the efficacy of ACR hydrogel bait. The field trial demonstrated that ACR hydrogel bait containing 0.005% fipronil with various attractants is highly effective and that ant densities throughout the baited plots declined by >99% within 7 days. CONCLUSIONS: The results of this study demonstrate that: (i) fipronil is highly effective for Argentine ant control in natural areas when used in low concentrations (0.005%); (ii) ACR hydrogels are an effective tool for delivering liquid baits to Argentine ants; and (iii) hydrogel baits augmented with various attractants including salt, protein and pheromone are highly attractive to Argentine ants. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Development and Evaluation of the Biological Activities of a Plain Mucoadhesive Hydrogel as a Potential Vehicle for Oral Mucosal Drug Delivery.

This study aimed to develop HGs based on cationic guar gum (CGG), polyethylene glycol (PEG), propylene glycol (PG), and citric acid (CA) using a 2k factorial experimental design to optimize their properties. HGs were characterized through FTIR and Raman spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The biological activities of HGs were determined by evaluating their mucoadhesive capacity and antibacterial activity in vitro, whereas their toxicity was analyzed using Artemia salina nauplii as an in vivo model. Results revealed that HGs were successfully optimized for their viscosity, pH, and sensory properties, and it was observed that varying concentrations of PEG-75 did not influence them. Through SEM analyses, it was noted that increased levels of PEG-75 resulted in HGs with distinct porosity and textures, whereas FTIR and Raman spectroscopy exhibited representative peaks of the raw materials used during the synthesis process. TGA studies indicated the thermal stability of HGs, as they presented degradation patterns at 100 and 300 °C. The synthesized HGs exhibited similar mucoadhesion kinetic profiles, demonstrating a displacement factor at an equilibrium of 0.57 mm/mg at 5 min. The antibacterial activity of HGs was appraised as poor against Gram-positive and Gram-negative bacteria due to their MIC90 values (>500 µg/mL). Regarding A. salina, treatment with HGs neither decreased their viability nor induced morphological changes. The obtained results suggest the suitability of CGG/PEG HGs for oral mucosa drug delivery and expand the knowledge about their mucoadhesive capacity, antibacterial potential, and in vivo biocompatibility.

Polysaccharide-based sustainable hydrogel spheres for controlled release of agricultural inputs.

Producing food in quantity and quality to meet the growing population demand is a challenge for the coming years. In addition to the need to improve the use and efficiency of conventional agricultural inputs, we face climate change and disparity in access to food. In this context, creating innovative, efficient, and ecologically approaches is necessary to transform this global scenario. Several delivery systems are being developed to encapsulate agrochemicals, aiming to improve the controlled release of active ingredients and protect them against environmental biotic and abiotic factors. Among these systems, hydrogel spheres are particularly notable for their ability to be fabricated from biodegradable materials, allowing the encapsulation of molecules, nanomaterials, and even organisms (e.g., bacteria and fungi). This review provides an overview of the latest progress in developing polysaccharide-based hydrogel spheres for agriculture. In addition, we describe methods for preparing hydrogel spheres and discuss the encapsulation and release of agricultural inputs in the field. Finally, we put hydrogel spheres into perspective and seek to highlight some current challenges in the field to spark new inspiration and improve the development of environmentally friendly and cost-effective delivery systems for the agricultural sector.

Biological Evaluation of Thermosensitive Hydrogels of Chitosan/Hydrolyzed Collagen/ß-GP in an In Vitro Model of Induced Cardiac Ischemia.

Ischemic events can culminate in acute myocardial infarction, which is generated by irreversible cardiac lesions that cannot be restored due to the limited regenerative capacity of the heart. Cardiac cell therapy aims to replace injured or necrotic cells with healthy and functional cells. Tissue engineering and cardiovascular regenerative medicine propose therapeutic alternatives using biomaterials that mimic the native extracellular environment and improve cellular and tissue functionality. This investigation evaluates the effect of thermosensitive hydrogels, and murine fetal ventricular cardiomyocytes encapsulated in thermosensitive hydrogels, on the contractile function of cardiomyocyte regeneration during an ischemic event. Chitosan and hydrolyzed collagen thermosensitive hydrogels were developed, and they were physically and chemically characterized. Likewise, their biocompatibility was evaluated through cytotoxicity assays by MTT, LDH, and their hemolytic capacity. The hydrogels, and cells inside the hydrogels, were used as an intervention for primary cardiomyocytes under hypoxic conditions to determine the restoration of the contractile capacity by measuring intracellular calcium levels and the expressions of binding proteins, such as a-actinin and connexin 43. These results evidence the potential of natural thermosensitive hydrogels to restore the bioelectrical functionality of ischemic cardiomyocytes.

Applying Different Conditions in the OphthalMimic Device Using Polymeric and Hydrogel-Based Hybrid Membranes to Evaluate Gels and Nanostructured Ophthalmic Formulations.

The OphthalMimic is a 3D-printed device that simulates human ocular conditions with artificial lacrimal flow, cul-de-sac area, moving eyelid, and a surface to interact with ophthalmic formulations. All tests with such a device have used a continuous artificial tear flow rate of 1 mL/min for 5 min. Here, we implemented protocol variations regarding the application time and simulated tear flow to increase the test's discrimination and achieve reliable performance results. The new protocols incorporated the previously evaluated 0.2% fluconazole formulations containing or not chitosan as a mucoadhesive component (PLX16CS10 and PLX16, respectively) and novel moxifloxacin 5% formulations, either in a conventional formulation and a microemulsion (CONTROL and NEMOX, respectively). The flow rate was reduced by 50%, and a pre-flow application period was also included to allow formulation interaction with the membrane. The OphthalMimic model was used with both polymeric and hydrogel-based hybrid membranes, including a simulated eyelid. Lowering the flow made it feasible to prolong the testing duration, enhancing device discrimination potential. The hydrogel membrane was adequate for testing nanostructure formulations. The OphthalMimic device demonstrated once again to be a versatile method for evaluating the performance of ophthalmic drug formulations with the potential of reducing the use of animals for experimentation.

Analysis of Structural Changes of pH-Thermo-Responsive Nanoparticles in Polymeric Hydrogels.

The pH- and thermo-responsive behavior of polymeric hydrogels MC-co-MA have been studied in detail using dynamic light scattering DLS, scanning electron microscopy SEM, nuclear magnetic resonance (1H NMR) and rheology to evaluate the conformational changes, swelling-shrinkage, stability, the ability to flow and the diffusion process of nanoparticles at several temperatures. Furthermore, polymeric systems functionalized with acrylic acid MC and acrylamide MA were subjected to a titration process with a calcium chloride CaCl2 solution to analyze its effect on the average particle diameter Dz, polymer structure and the intra- and intermolecular interactions in order to provide a responsive polymer network that can be used as a possible nanocarrier for drug delivery with several benefits. The results confirmed that the structural changes in the sensitive hydrogels are highly dependent on the corresponding critical solution temperature CST of the carboxylic (-COOH) and amide (-CONH2) functional groups and the influence of calcium ions Ca2+ on the formation or breaking of hydrogen bonds, as well as the decrease in electrostatic repulsions generated between the polymer chains contributing to a particle agglomeration phenomenon. The temperature leads to a re-arrangement of the polymer chains, affecting the viscoelastic properties of the hydrogels. In addition, the diffusion coefficients D of nanoparticles were evaluated, showing a closeness among with the morphology, shape, size and temperature, resulting in slower diffusions for larger particles size and, conversely, the diffusion in the medium increasing as the polymer size is reduced. Therefore, the hydrogels exhibited a remarkable response to pH and temperature variations in the environment. During this research, the functionality and behavior of the polymeric nanoparticles were observed under different analysis conditions, which revealed notable structural changes and further demonstrated the nanoparticles promising high potential for drug delivery applications. Hence, these results have sparked significant interest in various scientific, industrial and technological fields.

Biodegradable Cassava Starch/Phosphorite/Citric Acid Based Hydrogel for Slow Release of Phosphorus: In Vitro Study.

Phosphorous (P) is one the most important elements in several biological cycles, and is a fundamental component of soil, plants and living organisms. P has a low mobility and is quickly adsorbed on clayey soils, limiting its availability and absorption by plants. Here, biodegradable hydrogels based on Cassava starch crosslinked with citric acid (CA) were made and loaded with KH2PO4 and phosphorite to promote the slow release of phosphorus, the storing of water, and the reduction in P requirements during fertilization operations. Crosslinking as a function of CA concentrations was investigated by ATR-FTIR and TGA. The water absorption capacity (WAC) and P release, under different humic acid concentration regimens, were studied by in vitro tests. It is concluded that hydrogel formed from 10% w/w of CA showed the lowest WAC because of a high crosslinking degree. Hydrogel containing 10% w/w of phosphorite was shown to be useful to encouraging the slow release of P, its release behavior being fitted to the Higuchi kinetics model. In addition, P release increased as humic acid contents were increased. These findings suggest that these hydrogels could be used for encouraging P slow release during crop production.

Conductive extracellular matrix derived/chitosan methacrylate/ graphene oxide-pegylated hybrid hydrogel for cell expansion.

Electrical stimulation has emerged as a cornerstone technique in the rapidly evolving field of biomedical engineering, particularly within the realms of tissue engineering and regenerative medicine. It facilitates cell growth, proliferation, and differentiation, thereby advancing the development of accurate tissue models and enhancing drug-testing methodologies. Conductive hydrogels, which enable the conduction of microcurrents in 3D in vitro cultures, are central to this advancement. The integration of high-electroconductive nanomaterials, such as graphene oxide (GO), into hydrogels has revolutionized their mechanical and conductivity properties. Here, we introduce a novel electrostimulation assay utilizing a hybrid hydrogel composed of methacryloyl-modified small intestine submucosa (SIS) dECM (SISMA), chitosan methacrylate (ChiMA), and GO-polyethylene glycol (GO-PEG) in a 3D in vitro culture within a hypoxic environment of umbilical cord blood cells (UCBCs). Results not only demonstrate significant cell proliferation within 3D constructs exposed to microcurrents and early growth factors but also highlight the hybrid hydrogel's physiochemical prowess through comprehensive rheological, morphological, and conductivity analyses. Further experiments will focus on identifying the regulatory pathways of cells subjected to electrical stimulation.

Collagen-ß-cyclodextrin hydrogels for advanced wound dressings: super-swelling, antibacterial action, inflammation modulation, and controlled drug release.

A key strategy in enhancing the efficacy of collagen-based hydrogels involves incorporating polysaccharides, which have shown great promise for wound healing. In this study, semi-interpenetrating polymeric network (semi-IPN) hydrogels comprised of collagen (Col) with the macrocyclic oligosaccharide ß-cyclodextrin (ß-CD) (20-80 wt.%) were synthesised. Fourier-transform infrared (FTIR) spectroscopy confirmed the successful fabrication of these Col/ß-CD hydrogels, evidenced by the presence of characteristic absorption bands, including the urea bond band at ∼1740 cm-1, related with collagen crosslinking. Higher ß-CD content was associated with increased crosslinking, higher swelling, and faster gelation. The ß-CD content directly influenced the morphology and semi-crystallinity. All Col/ß-CD hydrogels displayed superabsorbent properties, enhanced thermal stability, and exhibited slow degradation rates. Mechanical properties were significantly improved with contents higher than ß-CD 40 wt.%. These hydrogels inhibited the growth of Escherichia coli bacteria and facilitated the controlled release of agents, such as malachite green, methylene blue, and ketorolac. The chemical composition of the Col/ß-CD hydrogels did not induce cytotoxic effects on monocytes and fibroblast cells. Instead, they actively promoted cellular metabolic activity, encouraging cell growth and proliferation. Moreover, cell signalling modulation was observed, leading to changes in the expression of TNF-α and IL-10 cytokines. In summary, the results of this research indicate that these novel hydrogels possess multifunctional characteristics, including biocompatibility, super-swelling capacity, good thermal, hydrolytic, and enzymatic degradation resistance, antibacterial activity, inflammation modulation, and the ability to be used for controlled delivery of therapeutic agents, indicating high potential for application in advanced wound dressings.

Green Foaming of Biologically Extracted Chitin Hydrogels Using Supercritical Carbon Dioxide for Scaffolding of Human Osteoblasts.

Chitin is a structural polysaccharide abundant in the biosphere. Chitin possesses a highly ordered crystalline structure that makes its processing a challenge. In this study, chitin hydrogels and methanogels, prepared by dissolution in calcium chloride/methanol, were subjected to supercritical carbon dioxide (scCO2) to produce porous materials for use as scaffolds for osteoblasts. The control of the morphology, porosity, and physicochemical properties of the produced materials was performed according to the operational conditions, as well as the co-solvent addition. The dissolution of CO2 in methanol co-solvent improved the sorption of the compressed fluid into the hydrogel, rendering highly porous chitin scaffolds. The chitin crystallinity index significantly decreased after processing the hydrogel in supercritical conditions, with a significant effect on its swelling capacity. The use of scCO2 with methanol co-solvent resulted in chitin scaffolds with characteristics adequate to the adhesion and proliferation of osteoblasts.

Fibrillogenesis in collagen hydrogels accelerated by carboxylated microbeads.

Collagen type I is a material widely used for 3D cell culture and tissue engineering. Different architectures, such as gels, sponges, membranes, and nanofibers, can be fabricated with it. In collagen hydrogels, the formation of fibrils and fibers depends on various parameters, such as the source of collagen, pH, temperature, concentration, age, etc. In this work, we study the fibrillogenesis process in collagen type I hydrogels with different types of microbeads embedded, using optical techniques such as turbidity assay and confocal reflectance microscopy. We observe that microbeads embedded in the collagen matrix hydrogels modify the fibrillogenesis. Our results show that carboxylated fluorescent microbeads accelerate 3.6 times the gelation, while silica microbeads slow down the formation of collagen fibrils by a factor of 1.9, both compared to pure collagen hydrogels. Our observations suggest that carboxylate microbeads act as nucleation sites and the early collagen fibrils bind to the microbeads.

The rheology of injectable hyaluronic acid hydrogels used as facial fillers: A review.

Injectable hyaluronic acid (HA) hydrogels have been popularized in facial aesthetics as they provide a long-lasting effect, low risk of complications, allergenicity tests are not required before application and can be easily removed by the action of hyaluronidases. On the other hand, the development of these systems requires in-depth studies of chemical mechanisms involved in hydrogel formation. Ideal dermal fillers should temporarily fluidize during extrusion through the needle and quickly recover their original shape after application. Hydrogels with more elastic properties, for example, are difficult to inject while viscous materials are too liquid. A balance between both properties should be achieved. Each region of the face requires products with distinct rheological properties. High G' dermal fillers are preferable for deeper wrinkles whereas the counterpart with lower values of G' is more indicated in superficial wrinkles or lip augmentation. Factors such as molecular weight and concentration of HA, pH, type and concentration of the crosslinking agent, particle size, crosslinking reaction time and crosslinking agent/polysaccharide ratio should be modulated to achieve specific rheological properties. In this review, the effect of each variable is discussed in detail to guide the rational development of new dermal fillers.

Evaluation of cellular viability in chitosan/L-arginine hydrogels.

BACKGROUND: There is a lack of studies evaluating the toxicity of nitric oxide (NO) precursors in chitosan/L-arginine hydrogels and their topical administration. However, clarifying the characteristics of these elements is essential for their possible use in non-surgical techniques of tooth movement acceleration. Such characteristics include interaction with different cell types, metabolism and drug safety. OBJECTIVES: This in vitro study aimed to assess the cytotoxicity of chitosan hydrogels on human HeLa cells using different concentrations of L-arginine. MATERIAL AND METHODS: The hydrogels were synthesized in a materials engineering laboratory, with a controlled environment, using 4 different L-arginine concentrations of 0%, 10%, 15%, and 20%. Once the hydrogels were prepared, their physical and chemical properties were characterized, and viability analysis was performed using 2 different methods, including a 48-h assay with Artemia salina nauplii and a 24-h cell culture with human HeLa cells followed by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) proliferation assay. Data analysis was performed using a Mann-Whitney U test to evaluate positive and negative controls in the cell culture, with a significance level of 0.01. A Wilcoxon paired test contrasted the 24-h compared to 48-h Artemia salina assays, with a Kruskal-Wallis and post hoc Dunn test used to compare groups using a significance level of 0.05. RESULTS: In the more viscous hydrogels, Artemia salina nauplii decreased drastically in 24 h, while the 15% and 20% hydrogels had no statistical differences from the negative control. The 10% and 20% hydrogels were statistically different from the negative control when comparing cell culture data. CONCLUSIONS: Our findings suggest that chitosan/L-arginine hydrogels could be used in humans without toxic effects. However, more trials and tests are needed to evaluate tooth movement rate during orthodontic treatment.

Subcutaneous Application of a Gelatin/Hyaluronic Acid Hydrogel Induces the Production of Skin Extracellular Matrix.

The development of injectable hydrogels with natural biopolymers such as gelatin (Ge) and hyaluronic acid (Ha) is widely performed due to their biocompatibility and biodegradability. The combination of both polymers crosslinked with N-Ethyl-N'-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) can be used as an innovative dermal filler that stimulates fibroblast activity and increases skin elasticity and tightness. Thus, crosslinked Ge/Ha hydrogels with different concentrations of EDC were administered subcutaneously to test their efficacy in young and old rats. At higher EDC concentrations, the viscosity decreases while the particle size of the hydrogels increases. At all concentrations of EDC, amino and carboxyl groups are present. The histological analysis shows an acute inflammatory response, which disappears seven days after application. At one and three months post-treatment, no remains of the hydrogels are found, and the number of fibroblasts increases in all groups in comparison with the control. In addition, the elastic modulus of the skin increases after three months of treatment. Because EDC-crosslinked Ge/Ha hydrogels are biocompatible and induce increased skin tension, fibroblast proliferation, and de novo extracellular matrix production, we propose their use as a treatment to attenuate wrinkles and expression lines.

Injectable Hydrogels for Nervous Tissue Repair-A Brief Review.

The repair of nervous tissue is a critical research field in tissue engineering because of the degenerative process in the injured nervous system. In this review, we summarize the progress of injectable hydrogels using in vitro and in vivo studies for the regeneration and repair of nervous tissue. Traditional treatments have not been favorable for patients, as they are invasive and inefficient; therefore, injectable hydrogels are promising for the treatment of damaged tissue. This review will contribute to a better understanding of injectable hydrogels as potential scaffolds and drug delivery system for neural tissue engineering applications.

In Vitro and In Vivo Evaluation of Chitosan/HPMC/Insulin Hydrogel for Wound Healing Applications.

Treatment of chronic wounds is challenging, and the development of different formulations based on insulin has shown efficacy due to their ability to regulate oxidative stress and inflammatory reactions. The formulation of insulin with polysaccharides in biohybrid hydrogel systems has the advantage of synergistically combining the bioactivity of the protein with the biocompatibility and hydrogel properties of polysaccharides. In this study, a hydrogel formulation containing insulin, chitosan, and hydroxypropyl methyl cellulose (Chi/HPMC/Ins) was prepared and characterized by FTIR, thermogravimetric, and gel point analyses. The in vitro cell viability and cell migration potential of the Chi/HPMC/Ins hydrogel were evaluated in human keratinocyte cells (HaCat) by MTT and wound scratch assay. The hydrogel was applied to excisional full-thickness wounds in diabetic mice for twenty days for in vivo studies. Cell viability studies indicated no cytotoxicity of the Chi/HPMC/Ins hydrogel. Moreover, the Chi/HPMC/Ins hydrogel promoted faster gap closure in the scratch assay. In vivo, the wounds treated with the Chi/HPMC/Ins hydrogel resulted in faster wound closure, formation of a more organized granulation tissue, and hair follicle regeneration. These results suggest that Chi/HPMC/Ins hydrogels might promote wound healing in vitro and in vivo and could be a new potential dressing for wound healing.

Synthesis, Characterization and Catechol-Based Bioinspired Adhesive Properties in Wet Medium of Poly(2-Hydroxyethyl Methacrylate-co-Acrylamide) Hydrogels.

Hydrogels consist of crosslinked hydrophilic polymers from which their mechanical properties can be modulated for a wide variety of applications. In the last decade, many catechol-based bioinspired adhesives have been developed following the strategy of incorporating catechol moieties into polymeric backbones. In this work, in order to further investigate the adhesive properties of hydrogels and their potential advantages, several hydrogels based on poly(2-hydroxyethyl methacrylate-co-acrylamide) with N'N-methylene-bisacrylamide (MBA), without/with L-3,4-dihydroxyphenylalanine (DOPA) as a catecholic crosslinker, were prepared via free radical copolymerization. 2-Hydroxyethyl methacrylate (HEMA) and acrylamide (AAm) were used as comonomers and MBA and DOPA both as crosslinking agents at 0.1, 0.3, and 0.5 mol.-%, respectively. The polymeric hydrogels were characterized by Fourier transform infrared spectroscopy (FT-IR), thermal analysis and swelling behavior analysis. Subsequently, the mechanical properties of hydrogels were determined. The elastic properties of the hydrogels were quantified using Young's modulus (stress-strain curves). According to the results herein, the hydrogel with a feed monomer ratio of 1:1 at 0.3 mol.-% of MBA and DOPA displayed the highest rigidity and higher failure shear stress (greater adhesive properties). In addition, the fracture lap shear strength of the biomimetic polymeric hydrogel was eight times higher than the initial one (only containing MBA); however at 0.5 mol.-% MBA/DOPA, it was only two times higher. It is understood that when two polymer surfaces are brought into close contact, physical self-bonding (Van der Waals forces) at the interface may occur in an -OH interaction with wet contacting surfaces. The hydrogels with DOPA provided an enhancement in the flexibility compared to unmodified hydrogels, alongside reduced swelling behavior on the biomimetic hydrogels. This approach expands the possible applications of hydrogels as adhesive materials, in wet conditions, within scaffolds that are commonly used as biomaterials in cartilage tissue engineering.

Bacterial nanocellulose/calcium alginate hydrogel for the treatment of burns

Purpose: Bacterial cellulose (BC) has shown high capacity for the treatment of wounds and burns, providing a moisty environment. Calcium alginate can be associated with BC to create gels that aid in wound debridement and contribute to appropriate wound healing. This study is aimed at characterizing and evaluating the use of bacterial cellulose/alginate gel in skin burns in rats. Methods: Cellulose and cellulose/alginate gels were compared regarding the capacity of liquid absorption, moisture, viscosity, and potential cytotoxicity. The 2nd degree burns were produced using an aluminum metal plate (2.0cm) at 120ºC for 20s on the back of rats. The animals were divided into non-treated, CMC(Carboxymethylcellulose), Cellulose(CMC with bacterial cellulose), and Cellulose/alginate(CMC with bacterial cellulose and alginate). The animals received topical treatment 3 times/week. Biochemical (MPO, NAG and oxidative stress), histomorphometry and immunohistochemical assays (IL-1ß IL-10 and VEGF) were conducted on the 14th, 21st, 28th, and 35th days. Results: Cellulose/Alginate gel showed higher absorption capacity and viscosity compared to Cellulose gel, with no cytotoxic effects. Cellulose/alginate presented lower MPO values, a higher percentage of IL-10, with greater and balanced oxidative stress profile. Conclusions: The use of cellulose/alginate gel reduced neutrophils and macrophage activation and showed greater anti-inflammatory response, which can contribute to healing chronic wounds and burns.