Higher Moisture Retention Research Articles

Investigation of Tannic Acid Crosslinked PVA/PEI-Based Hydrogels as Potential Wound Dressings with Self-Healing and High Antibacterial Properties

This study developed hydrogels containing different ratios of TA using polyvinyl alcohol (PVA) and polyethyleneimine (PEI) polymers crosslinked with tannic acid (TA) for the treatment of burn wounds. Various tests, such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), swelling, moisture retention, contact angle, tensile strength, the scratch test, antibacterial activity and the in vitro drug-release test, were applied to characterize the developed hydrogels. Additionally, the hydrogels were examined for cytotoxic properties and cell viability with the WST-1 test. TA improved both the self-healing properties of the hydrogels and showed antibacterial activity, while the added gentamicin (GEN) further increased the antibacterial activities of the hydrogels. The hydrogels exhibited good hydrophilic properties and high swelling capacity, moisture retention, and excellent antibacterial activity, especially to S. aureus. In addition, the swelling and drug-release kinetics of hydrogels were investigated, and while swelling of hydrogels obeyed the pseudo-second-order modeling, the drug release occurred in a diffusion-controlled manner according to the Higuchi and Korsmeyer–Peppas models. These results show that PVA/PEI-based hydrogels have promising potential for wound dressings with increased mechanical strength, swelling, moisture retention, self-healing, and antibacterial properties.

Evaluating the Use of Sacran, a Polysaccharide Isolated from Aphanothece sacrum, as a Possible Microbicide for Preventing HIV-1 Infection.

Since combination antiretroviral therapy (cART) was introduced to treat human immunodeficiency virus type-1 (HIV-1)/acquired immunodeficiency syndrome (AIDS), the AIDS mortality rate has markedly decreased, and convalescence in individuals with HIV has improved drastically. However, sexual transmission has made HIV-1 a global epidemic. Sacran is a megamolecular polysaccharide extracted from cyanobacterium Aphanothece sacrum that exhibits numerous desirable characteristics for transdermic applications, such as safety as a biomaterial, a high moisture retention effect, the ability to form a film and hydrogel, and an anti-inflammatory effect. In this study, we evaluated the anti-HIV-1 effects in sacran as a barrier to HIV-1 transmission. Sacran inhibited HIV-1 infection and envelope-dependent cell-to-cell fusion. Moreover, we used a Transwell assay to confirm that sacran inhibited viral diffusion and captured viruses. The synergistic effects of sacran and other anti-HIV infection drugs were also evaluated. HIV-1 infections can be reduced through the synergistic effects of sacran and anti-HIV-1 drugs. Our study suggests using sacran gel to provide protection against HIV-1 transmission.

CHEMICAL MODIFICATION AND BIOLOGICAL ACTIVITY OF ALGINATE-BASED HYDROGELS

In recent years, the problem of wound infection has risen dramatically. Infectious complications of surgical wounds have increased significantly, often leading to severe sepsis. Gram-negative bacteria and microorganisms, which are immune to virtually all currently available antimicrobials, are the main culprits. In this regard, the development and implementation of innovative drugs and wound dressings, purulent and chronic wound treatment methods is an urgent problem of many domestic and foreign researchers. Brown algae are extracted using an alkaline solution to produce the ionic polysaccharide sodium alginate. It still holds one of the top positions among water-soluble polymers of natural origin as a result of various highly useful practical characteristics. Based on alginate hydrogels, it is possible to create new materials for biotechnological, pharmaceutical and medical purposes, as they have high moisture retention capacity, non-toxicity and self-decomposing ability. After reviewing the literature, we concluded that cefepime is a new antibiotic researched for wound dressing using IV generation cephalosporins as an antibacterial agent. It is highly resistant to hydrolysis by most beta-lactamases and quickly penetrates the cells of gram-negative bacteria. Inside the bacterial cell, it targets penicillin-binding proteins. To obtain new derivatives of sodium alginate with special properties, a chemical method, in particular, thiolene reactions, was used. It should be noted that click chemistry refers to a set of chemical reactions for the rapid and reliable synthesis of compounds by the uniform addition of individual components. Thiolene reactions offer significant advantages, includingversatile reaction conditions (including radical reactions and catalytic processes) and the ability to use a wide range of substrates with different unsaturated bonds such as acrylates, methacrylates and ethers. To monitor the rate and efficiency of UV activation, we used a sol-gel assay technique that allowed us to quantify insoluble (spatially cross-linked) and soluble polymers. After UV activation, samples with different ratios of thiol derivative (S-H bond) showed low viscosity, indicating the predominant degradation of polymer molecules in these systems. Since alginate-polymer derivatives primarily exhibit deconstructive behavior, the dominant process in alginate molecules is the breaking of bonds rather than their formation. The size of the gel fraction reflects the efficiency of polymer cross-linking, which in turn affects the efficiency of immobilization of the drug in the hydrogel matrix and its release rate. This study presents an experimental characterization of photocrosslinked hydrogels aimed at evaluating and elucidating the physicochemical and biological properties of the antibiotic cefepime in an alginate polymer. The obtained kinetic parameters of the swelling-dissolving process show that the synthesized alginate hydrogel is capable of providing a diffused and prolonged release of drugs. In addition, the synthesized hydrogel effectively delivers cefepime to the tested bacterial strains, showing high antibacterial activity without toxicity. However, further in vivo studies are needed to evaluate the fate and toxicity of the alginate-based hydrogel before definitive conclusions can be drawn regarding the usefulness of the synthesized drugs. These preliminary results can be the basis for the development of medical products.

Innovation in Cassava Bagasse Valorization: Efficiency of Convective Drying Enhanced with Ultrasound and Pulsed Electric Fields.

This research proposes an efficient alternative for dehydrating cassava bagasse to address the inherent challenges in the handling, transportation, storage, and preservation of this agro-industrial residue generated in cassava starch production plants. This residue is characterized by high moisture retention, considerable volume, and hydrophilic nature, complicating conventional drying methods. This study evaluates the impact of emerging ultrasound (US) and pulsed electric field (PEF) technologies prior to convective drying to enhance the dehydration efficiency of cassava bagasse, aiming at its valorization and contributing to the sustainability of the cassava starch industry. The findings reveal that pretreatment with ultrasound (US) and pulsed electric fields (PEF) significantly reduces the drying time of cassava bagasse compared to convective drying alone. With probe ultrasound at 26 kHz for 30 min, the drying time is reduced by 72% (3.83 h vs. 14.0 h); with bath ultrasound at 37 kHz for 30 min, it is reduced by 56.0% (6.16 h vs. 14.0 h); and with PEF at 7.5 kV/cm for 30 min, it is reduced by 52.4% (6.66 h vs. 14.0 h). These emerging technologies increased the effective diffusivity and modified the molecular structure of the bagasse, thereby improving mass transfer and drying process efficiency. These results are particularly useful for developing more efficient and sustainable strategies for drying agricultural by-products, with direct implications for the post-industrial treatment of agro-industrial residues with high water content.

Effect of different sous-vide cooking temperature-time combinations on the functional and sensory properties of goose meat

The effect of goose meat sous-vide (SV) cooking at 6 combinations of temperature (60°C, 80°C) and time (4, 6, 12h) on selected functional properties was investigated. The study conducted an assessment of cooking loss (CL), moisture content, pH, longitudinal (LS), and transverse (TS) shrinkage, shear force (SF), texture profile analysis (TPA), color parameters (L*, a*, b*, C, h°), ΔE and carried out sensory evaluation. A total of 168 breast muscles (BM with and without skin) from 17-wk-old "Polish oat geese" were utilized. The CL was affected by both cooking temperature and time. The CL for meat with skin was higher than for without ones, and it was lower for both kinds of meat cooked at 60°C than at 80°C for all cooking times. The LS was higher than the TS. The higher shrinkage was stated for meat cooked at 80°C. There was a reduction in moisture content and slightly increasing pH by increasing temperature and prolonging cooking time. For both kinds of meat, the highest moisture retention was stated at 60°C/4h, and the lowest in samples heated at 80°C/12h. The samples cooked at 60°C were characterized by a higher L* value than those at 80°C. The a* values were higher for samples cooked at 60°C than those at 80°C, whereas b* were higher for meat cooked at 80°C. The SF exhibited a trend of lower values at 60°C compared to samples cooked at 80°C and it increased with prolonged cooking time. The value of hardness, cohesiveness, springiness, gumminess, and chewiness for meat cooked at 60°C increased, and for samples cooked at 80°C decreased with increasing cooking time. It was no significant differences in sensory scores for overall palatability for both kinds of meat cooked at 60°C and 80°C. Goose meat cooked at different time and temperature combinations showed extremely desirable overall palatability. Taking into account all discussed parameters, the optimal combination seems to be 60°C/4h.

Mulching and drip irrigation to mitigate soil salinity on tomato (Lycoperscon esculentum L.) production in coastal area

Bangladesh’s coastal regions are rich in saline water resources. The majority of these resources are still not being used to their full potential. In the southern Bangladeshi region of Patuakhali, research was conducted to investigate the effects of mulching and drip irrigation on tomato yield, quality, and blossom-end rot (BER) at different soil salinity thresholds. There were four distinct treatments applied: T1= drip irrigation with polythene mulch, T2 = drip irrigation with straw mulch, T3 = drip irrigation without mulch, and T4 = standard procedure. While soil salinity was much greater in treatment T3 (1.19–8.42 dS/m) fallowed by T4 (1.23–8.63 dS/m), T1 treatments had the lowest level of salinity and the highest moisture retention during every development stage of the crops, ranging from 1.28–4.29 dS/m. Treatment T3 exhibited the highest soil salinity levels (ranging from 1.19 to 8.42 dS/m), followed by T4 with a range of 1.23 to 8.63 dS/m. In contrast, T1 treatments consistently maintained the lowest salinity levels (ranging from 1.28 to 4.29 dS/m) and the highest moisture retention throughout all stages of crop development. In terms of yield, drip irrigation with no mulch treatment (T3) provided the lowest output (13.37 t/ha), whereas polyethylene mulching treatment (T1) produced the maximum yield (46.04 t/ha). According to the study, conserving moisture in tomato fields and reducing soil salinity may both be achieved with drip irrigation combined with polythene mulch. The research suggests that employing drip irrigation in conjunction with polythene mulch could effectively preserve moisture in tomato fields and concurrently decrease soil salinity.

Hydrogel foam dressings with angiogenic and immunomodulatory factors from mesenchymal stem cells.

Stem cell therapy and skin substitutes address the stalled healing of chronic wounds in order to promote wound closure; however, the high cost and regulatory hurdles of these treatments limit patient access. A low-cost method to induce bioactive healing has the potential to substantially improve patient care and prevent wound-induced limb loss. A previous study reported that bioactive factors derived from apoptotic-like mesenchymal stem cells (MSCs) demonstrated anti-inflammatory and proangiogenic effects and improved ischemic muscle regeneration. In this work, these MSC-derived bioactive factors were loaded into a hydrogel foam to harness immunomodulatory and angiogenic properties from MSC components to facilitate chronic wound healing without the high cost and translational challenges of cell therapies. After incorporation of bioactive factors, the hydrogel foam retained high absorbency, moisture retention, and target water vapor transmission rate. High loading efficiency was confirmed and release studies indicated that over 90% of loaded factors were released within 24 h. Ethylene oxide sterilization and 4-week storage did not affect the bioactive factor release profile or physical properties of the hydrogel foam dressing. Bioactivity retention of the released factors was also confirmed for as-sterilized, 4°C-stored, and -20°C-stored bioactive hydrogel foams as determined by relevant gene expression levels in treated pro-inflammatory (M1) macrophages. These results support the use of the bioactive dressings as an off-the-shelf product. Overall, this work reports a new method to achieve a first-line wound dressing with the potential to reduce persistent inflammation and promote angiogenesis in chronic wounds.

Farmers Knowledge on Indigenous Soil Types: A Review

This review explains the significance of smallholder farmers’ understanding of soil types as a dependable basis for subsistence crop production. The data presented in this review was sourced from literature on subsistence farming, indigenous soil nomenclature, and the suitability of various soils for different crop varieties. The review findings revealed four primary soil classifications, specifically loam, clay, sandy, and rocky, each exhibiting distinct variations in texture and colour. Farmers utilise soil texture and colour as indicators of the suitability of soil for certain crops. For example, black clay soil has high moisture retention and low susceptibility to erosion that mitigates the risk of crop failure. Farmers utilise this knowledge to mitigate the impacts of increasing temperatures and unpredictable precipitation patterns on the planting and management of crops. This type of adaptation mechanism could be incorporated into climate change adaptation policy to foster the use of community-based and innovative mechanisms to mitigate and cope with the negative impacts of climate change on subsistence food production. Keywords: Indigenous knowledge, ethnopedology, soil taxonomy, climate change, sustainable development, climate adaptation

Robust integration of "top-down" strategy and triple-structure design for nature-skin derived e-skin with superior elasticity and ascendency strain and vibration sensitivity

The rapid advancement of bio-integrated electronics in recent years has been paralleled by increased interest in the research of stretchable, elastic, conductive, and multi-dimensional sensing electronic skin (e-skin) due to its potential integration with electronic devices and soft tissues. In this work, we presented the fabrication of a nature-skin derived e-skin, denoted as S-P/G@PU e-skin, achieved through an on-demand "top-down" strategy and a triple structure design, employing integrated in-situ polymerization, impregnation, and encapsulation techniques. The collagen fibers weaved hierarchical 3D structure of natural skin, was strategically employed to host conductive polypyrrole and combined with a binary solvent system of glycerin and water. Subsequently, this composite natural skin was coated with polyurethane films, resulting in the engineering of the S-P/G@PU e-skin. This innovative e-skin exhibited remarkable properties, including high tensile strength (8.76 MPa), excellent elasticity (0–180 %), anti-freezing capacity, moisture retention, substantial conductivity (6.3 S/m), and outstanding multi-dimensional sensing capabilities. Importantly, the S-P/G@PU e-skin functioned as both a slow adaptive resistance strain sensor and a fast adaptive single-electrode triboelectric nanogenerator, making it a versatile sensing system that enabled real-time monitoring of various physiological signals from the human body and wide-frequency vibration signals from devices such as cellphones and motors. This study serves as a proof of concept for transforming nature-skin into e-skin, showcasing the potential for integrated wearable electronics, artificial intelligence, and human-machine interfaces.

Technical Evaluation of a New Medical Device Based on Rigenase in the Treatment of Chronic Skin Lesions.

Chronic wound is characterized by slow healing time, persistence, and abnormal healing progress. Therefore, serious complications can lead at worst to the tissue removal. In this scenario, there is an urgent need for an ideal dressing capable of high absorbency, moisture retention and antimicrobial properties. Herein we investigate the technical properties of a novel advanced non-woven triple layer gauze imbibed with a cream containing Rigenase, an aqueous extract of Triticum vulgare used for the treatment of skin injuries. To assess the applicability of this system we analyzed the dressing properties by wettability, dehydration, absorbency, Water Vapor Transmission Rate (WVTR), lateral diffusion and microbiological tests. The dressing showed an exudate absorption up to 50%. It created a most environment allowing a proper gaseous exchange as attested by the WVTR and a controlled dehydration rate. The results candidate the new dressing as an ideal medical device for the treatment of the chronic wound repairing process. It acts as a mechanical barrier providing a good management of the bacterial load and proper absorption of abundant wound exudate. Finally, its vertical transmission minimizes horizontal diffusion and side effects on perilesional skin as maceration and bacterial infection.

Fine adjustment of catalyst agglomerate for the controllable construction of Co/Fe–N–C catalyst layers

Adjusting catalyst/ionomer agglomerate is crucial to a high-performance catalyst layer (CL), particularly for non-precious metal catalysts. As a sacrificial component, the solvent plays a vital role during the CL formation process and resulting microstructure, determining the performance of the anion exchange membrane fuel cells (AEMFCs). Here, solvent mixtures of isopropanol (IPA) and tetrahydrofuran (THF) are studied for the controllable construction of the Co/Fe–N–C CL. The results indicate that the aggregate state of the ionomers and catalysts and the final CL microstructure strongly depend on the ratio of IPA and THF. The CL prepared with IPA: THF = 1:2 (v/v) shows a homogeneous distribution of Co/Fe–N–C catalysts, embedded in the ionomer matrix, due to the fast volatilization and low viscosity of the catalyst ink. The Co/Fe–N–C CL with high moisture adsorption behavior and retention ability results in a high performance AEMFC with peak power density of 545.3 mW cm−2 at 80 °C. The obtained results can guide the rational design of microstructure in non-precious metal CLs for high-performance AEMFCs.

H2O2-PLA-(Alg)2Ca Hydrogel Enriched in Matrigel® Promotes Diabetic Wound Healing.

Hydrogel-based dressings exhibit suitable features for successful wound healing, including flexibility, high water-vapor permeability and moisture retention, and exudate absorption capacity. Moreover, enriching the hydrogel matrix with additional therapeutic components has the potential to generate synergistic results. Thus, the present study centered on diabetic wound healing using a Matrigel-enriched alginate hydrogel embedded with polylactic acid (PLA) microspheres containing hydrogen peroxide (H2O2). The synthesis and physicochemical characterization of the samples, performed to evidence their compositional and microstructural features, swelling, and oxygen-entrapping capacity, were reported. For investigating the three-fold goal of the designed dressings (i.e., releasing oxygen at the wound site and maintaining a moist environment for faster healing, ensuring the absorption of a significant amount of exudate, and providing biocompatibility), in vivo biological tests on wounds of diabetic mice were approached. Evaluating multiple aspects during the healing process, the obtained composite material proved its efficiency for wound dressing applications by accelerating wound healing and promoting angiogenesis in diabetic skin injuries.

Effect of milk protein standardization using high milk protein ingredients on texture, composition and yield of paneer

The study was aimed to prepare good quality paneer in sensory and textural attributes with greater yield by inclusion of high protein powders to the milk. Paneer samples were prepared from buffalo milk, after standardization of protein:fat ratio (w/w) to 0.68 with addition of skimmed milk powder (SMP), milk protein concentrate 60 (MPC60) and sodium caseinate (NaCas). These paneer samples along with control paneer were analysed for yield, protein loss in whey, composition, microstructure, sensory and texture profile. All the paneer samples reported a significant increase in yield, the order being MPC60 (28%) > SMP (26 %) ≈ NaCas (26 %) > Control (18 %). Paneer manufactured using SMP and NaCas had hardest and softest body due to lowest and highest moisture retention, respectively. Paneer samples manufactured with MPC60 had highest protein content (33 %) due to lowest protein loss in whey. Sensory analysis revealed that paneer manufactured with MPC60 was best amongst all the samples with superior sensory attributes and highest overall acceptability. Texture profile analysis and microstructure evaluation revealed the differences in textural properties of paneer samples prepared using protein powders with control paneer. Good quality paneer with higher yield comparable to conventional can be prepared by standardization of protein:fat ratio to 0.68 with addition of MPC60.

Fabrication of Glutaraldehyde Vapor Treated PVA/SA/GO/ZnO Electrospun Nanofibers with High Liquid Absorbability for Antimicrobial of Staphylococcus aureus.

In this study, we aim to develop organic-inorganic hybrid nanofibers containing high moisture retention and good mechanical performance as an antimicrobial dressing platform. The main theme of this work focuses on several technical tasks including (a) the electrospinning process (ESP) to produce organic polyvinyl alcohol/sodium alginate (PVA/SA) nanofibers with an excellent diameter uniformity and fibrous orientation, (b) the fabrication of inorganic nanoparticles (NPs) as graphene oxide (GO) and ZnO NPs to be added to PVA/SA nanofibers for enhancement of the mechanical properties and an antibacterial function to Staphylococcus aureus (S. aureus), and then (c) the crosslinking process for PVA/SA/GO/ZnO hybrid nanofibers in glutaraldehyde (GA) vapor atmosphere to improve the hydrophilicity and moisture absorption of specimens. Our results clearly indicate that the uniformity nanofiber with 7 wt% PVA and 2 wt% SA condition demonstrates 199 ± 22 nm in diameter using an electrospinning precursor solution of 355 cP in viscosity by the ESP process. Moreover, the mechanical strength of nanofibers was enhanced by 17% after the handling of a 0.5 wt% GO nanoparticles addition. Significantly, the morphology and size of ZnO NPs can be affected by NaOH concentration, where 1 M NaOH was used in the synthesis of 23 nm ZnO NPs corresponding to effective inhibition of S. aureus strains. The PVA/SA/GO/ZnO mixture successfully performed an antibacterial ability with an 8 mm inhibition zone in S. aureus strains. Furthermore, the GA vapor as a crosslinking agent acting on PVA/SA/GO/ZnO nanofiber provided both swelling behavior and structural stability performance. The swelling ratio increased up to 1.406%, and the mechanical strength was 1.87 MPa after 48 h of GA vapor treatment. Finally, we successfully synthesized the hybrid nanofibers of GA-treated PVA/SA/GO/ZnO accompanied with high moisturizing, biocompatibility, and great mechanical properties, which will be a novel multi-functional candidate for wound dressing composites for patients receiving surgical operations and first aid treatments.

Effect of Malva neglecta and lactulose on survival of Lactobacillus fermentum and textural properties of synbiotic stirred yogurt.

Yogurt is a popular dairy product and its consumption has been progressively growing over the past few decades by raising consumers' health-consciousness. As yogurt is growing in popularity, manufacturers are continuously seeking for bioactive components such as probiotics and prebiotics, to produce functional yogurt with more beneficial health effects. Therefore, this study aimed to evaluate the effect of Malva neglecta (MN, 0, 5, 10 and 15%) and lactulose (0, 1 and 2%) as prebiotic substances on survival of Lactobacillus fermentum in a half-fat synbiotic stirred yogurt. The results revealed that with increasing MN and lactulose concentrations, the count of Lb. fermentum significantly increased (p < 0.05). At the end of 21-day cold storage, the count of probiotics in yogurt sample having 2% lactulose and 10-15% MN significantly was higher than control (8.37-8.4 vs. 7.73 Log cfu/g). With increasing the amount of MN and lactulose, firmness and chewiness of yogurt samples decreased while adhesiveness increased (p < 0.05). Scanning electron microscopy assessment shown that addition of MN and lactulose resulted in a higher moisture retention in the void spaces. The results revealed that by incorporating lactulose and MN in yogurt formulation, an appropriate synbiotic yogurt could be produced as a novel functional product.

New skin tissue engineering scaffold with sulfated silk fibroin/chitosan/hydroxyapatite and its application

Repairing skin wounds has always been challenging in clinical practice. The new skin tissue engineering scaffold provides innovative ways to address these challenges with a good chance of success because of its stable mechanical properties, biodegradability, and antibacterial properties. This paper presents the fabrication and evaluation of a three-dimensional composite scaffold made with sulfated silk fibroin, chitosan, and hydroxyapatite (SSF/CS/HAP). An electron microscope shows that the scaffold has an aperture of 15–20 μm, while an absorption performance test shows that its expansion index reaches 779%. The co-culture of L929 cells and the CCK-8 experiments demonstrated good cell compatibility and low scaffold cytotoxicity, respectively. Meanwhile, in vivo experiments demonstrate that rats with SSF/CS/HAP scaffold-treated neck wounds heal faster. In the wound skin tissue of the SSF/CS/HAP scaffold group, immunohistochemistry indicates a more rapid and mature development of hair follicles. This study successfully developed a novel skin tissue engineering scaffold material with high moisture retention, high tissue compatibility, and low cytotoxicity, demonstrating its ability to improve wound repair with promising potential for tissue engineering applications.

Intrinsically adhesive, conductive organohydrogel with high stretchable, moisture retention, anti-freezing and healable properties for monitoring of human motions and electrocardiogram

A novel self-adhesive conductive organohydrogel without catechol adhesive components is developed for long-term, continuous monitoring of human motions and electrocardiogram. The organohydrogel is achieved by covalent cross-linking polymerization of acrylamide, N-acryloylglycinamide, and reduced graphene oxide, followed by soaking into ethylene glycol-water mixture. The organohydrogel exhibits intrinsic adhesion to various substances, excellent healing ability of nearly 100% conductivity repair rate, long-lasting moisture retention (about 30 days), extreme temperature tolerance (–20–60 °C), stable conductivity and extraordinary mechanical properties with a maximum tensile strength of 300 kPa, high stretchability over 1700%, compressive stress over 5 MPa. This organohydrogel can adhere to human skin without other fixture for human motions monitoring, such as the bending of wrist, finger, elbow and knee, and throat actions. Moreover, the organohydrogel can achieve long-term, continuous monitoring of human ECG signals in various daily activities, such as a night of sleep, standing, walking, performing leg curls and leg presses, and using an elliptical machine. This research offers a new strategy to develop self-adhesive conductive organohydrogel for long-term, continuous, and imperceptible monitoring of human health signals.

Preparation and Evaluation of Bacterial Nanocellulose/Hyaluronic Acid Composite Artificial Cornea for Application of Corneal Transplantation.

The treatment for corneal damage requires donor corneal transplantation, but there is a serious scarcity of donor corneas worldwide. In this study, we aimed to design a new artificial cornea with good cytocompatibility, excellent optical properties and suture resistance, and great moisturizing properties. A new bacterial nanocellulose (BNC) membrane with anisotropic mechanical properties and high light transmission was produced in a horizontal rotary drum reactor. However, as a potential material for artificial keratoplasty, the transparency and mechanical properties of the new BNC membrane were not satisfactory. Thus, hyaluronic acid (HA) was introduced in the BNC to synthesize the BNC/HA composite membrane by using 1,4-butanediol diglycidyl ether (BDDE) as the chemical cross-linking agent. The micro-morphology, light transmittance, mechanical properties, water content, moisture retention ability, and cytocompatibility of the composite membranes were further evaluated. HA was fixed in the BNC network by the ether bond, and the composite membrane was found to have excellent light transmittance (up to 95.96%). The composite membrane showed excellent mechanical properties, for instance, its tensile strength exceeded the human normal intraocular pressure (IOP) (1.33-2.80 kPa), the maximum burst pressure was about 130 kPa, 46-97 times that of the normal IOP, and its suture force was close to that of the human amniotic membrane (0.1 N). Based on the three-dimensional network scaffold of BNC and the high water absorption characteristics of HA, the artificial cornea had high water content and high moisture retention ability. The rabbit corneal stromal cells cultured in vitro showed that the artificial cornea substitute had excellent cytocompatibility. BDDE is the most frequently used cross-linker in most HA products in the current cosmetic medicine industry owing to its long-term safety records for over 15 years. Therefore, the BNC/HA composite hydrogel cross-linked with BDDE has great potential in artificial keratoplasty or ocular surface repair.

Injectable redox albumin-based hydrogel with in-situ loaded dihydromyricetin

Albumin is widely used in clinics due to its demonstrated biological safety and functional flexibility. Hydrogels derived from natural albumin possess high moisture retention ability and good biodegradability, making albumin ideal biomaterials compared with synthetic polymers. Herein, by reducing disulfide bonds in bovine serum albumin molecules with glutathione and re-oxidizing the free thiols using dimethyl sulfoxide (DMSO) as additional oxidant, three-dimensional network was assembled, leading to the formation of hydrogel. Meanwhile, DMSO is also an excellent solvent for many drugs, and the hydrophobic drug dihydromyricetin (DMY) can be well dissolved in DMSO. During the crosslinking reaction, DMSO participated in fabricating a porous albumin hydrogel network. At the same time, increased loading of DMY and sustained release of DMY were achieved, improving bioavailability of hydrophobic drug DMY. Rheological test and cytotoxicity assay proved excellent elasticity and biocompatibility of the hydrogel. Self-healing property and narrow-needle injection provided potential application of the hydrogel as biomedical materials. This method for formation hydrogels and in situ loading of drugs may expand to preparing other drug loaded hydrogels and find wide applications.

Facile Fabrication of Chemically Modified Sodium Alginate Fibers With Enhanced Mechanical Performance

Sodium alginate fibers have been extensively studied due to being non-toxic and have high moisture retention, high oxygen permeability, biocompatibility, and biodegradability. However, their application has been limited due to their poor mechanical performance. In this study, poly(ethylene glycol) diglycidyl ether-modified sodium alginate fibers were prepared by spinning the solution after mixed reactions through a spinneret into a coagulation bath containing aqueous CaCl2. The properties of the spinning solution, the structure and physical properties of the modified sodium alginate fibers with various poly(ethylene glycol) diglycidyl ether contents were investigated. A poly(ethylene glycol) diglycidyl ether content of the modified sodium alginate fibers of 15 wt% gave optimal breaking strength and elongation at break, improving them by 78 % and 114 %, respectively, compared with pure sodium alginate fibers. The thermal stability of the modified sodium alginate fibers was also improved.