Chemical Cross-linking Research Articles

Wood Polymer Composites Based on the Recycled Polyethylene Blends from Municipal Waste and Ethiopian Indigenous Bamboo (Oxytenanthera abyssinica) Fibrous Particles Through Chemical Coupling Crosslinking.

Valorization of potential thermoplastic waste is an effective strategy to address resource scarcity and reduce valuable thermoplastic waste. In this study, new ecofriendly biomass-derived wood polymer composites (WPCs) were produced from three different types of recycled polyethylene (PE) municipal waste, namely linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), or high-density polyethylene (HDPE), and their blend with equal composition (33/33/33 by wt.%). Bamboo particle reinforcement derived from indigenous Ethiopian lowland bamboo (LLB), which had never been utilized before in a WPC formulation, was used as the dispersed phase. Before utilization, recycled LLDPE, MDPE, and HDPE were carefully characterized to determine their chemical compositions, residual metals, polycyclic aromatic hydrocarbons, and thermal properties. Similarly, the fundamental mechanical properties of the WPCs, such as tensile strength, modulus of elasticity, flexural strength, modulus of rupture, and unnotched impact strength, were evaluated. Finally, the thermal stability and interphase coupling efficiency of maleic-anhydride-grafted polypropylene (MAPP) were carefully investigated. WPCs formulated by melt-blending either of the recycled PEs or the blend of recycled PE with bamboo particles showed significant improvement due to MAPP enhancing interfacial adhesion and thermally induced crosslinking, despite inherent immiscibility. These results were confirmed using Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The formulated WPCs may promote PE waste cascading valorization, offering sustainable alternatives and maximizing LLB utilization. Furthermore, comparison with well-known standards for polyolefin-based WPCs indicated that the prepared WPCs can be used as alternative sustainable building materials and related applications.

Optical characterization of molecular interaction strength in protein condensates.

Biomolecular condensates have been identified as a ubiquitous means of intracellular organization, exhibiting very diverse material properties. However, techniques to characterize these material properties and their underlying molecular interactions are scarce. Here, we introduce two optical techniques - Brillouin microscopy and quantitative phase imaging (QPI) - to address this scarcity. We establish Brillouin shift and linewidth as measures for average molecular interaction and dissipation strength, respectively, and we used QPI to obtain the protein concentration within the condensates. We monitored the response of condensates formed by FUS and by the low-complexity domain of hnRNPA1 (A1-LCD) to altering temperature and ion concentration. Conditions favoring phase separation increased Brillouin shift, linewidth, and protein concentration. In comparison to solidification by chemical crosslinking, the ion-dependent aging of FUS condensates had a small effect on the molecular interaction strength inside. Finally, we investigated how sequence variations of A1-LCD, that change the driving force for phase separation, alter the physical properties of the respective condensates. Our results provide a new experimental perspective on the material properties of protein condensates. Robust and quantitative experimental approaches such as the presented ones will be crucial for understanding how the physical properties of biological condensates determine their function and dysfunction.

Synergistic Dual-Cross-Linking Gelation: Exploring the Impact of Metal-Ligand Complexation on Ionogel Performance.

Owing to the growing interest in wearable ionotronics, the demand for ionogels with outstanding mechanical and electrochemical characteristics has increased dramatically. Nevertheless, it remains challenging to simultaneously enhance the mechanical robustness and conductivity of ionogels because of their trade-off relationship. In this work, we propose physically/chemically dual-cross-linked ionogels designed to improve the mechanical strength without reducing ionic conductivity by introducing metal-ligand complexation only within the physically cross-linked domains. In particular, the impact of metal-ligand complexation, a crucial parameter in this strategy, on ionogel performance is systematically examined using various metal ions. The mechanical resilience and thermal stability of ionogels are effectively enhanced with Co3+ having the highest coordination number, which can be explained by the highest metal-ligand complexation (i.e., chemical cross-linking) density. Additionally, there is no degradation in ionic conductivity when compared to the pristine ionogel because these complexations occur within physically cross-linking domains that are irrelevant to the ion conductive channels. The dual-cross-linked ionogels are successfully applied to alternating-current electroluminescent displays (ACEDs). Moreover, a versatile mixed-emitter strategy is suggested to improve practicality, enabling the realization of frequency-controlled multicolor ACEDs.

High Ion-Conductive Hydrogel: Soft, Elastic, with Wide Humidity Tolerance and Long-Term Stability.

Ion-conductive hydrogels have received great attention due to their significant potential in flexible electronics. However, achieving hydrogels that simultaneously possess high ionic conductivity and stability under varying humidity conditions remains a challenge, limiting their practical applications. Herein, we propose a thermally controlled chemical cross-linking strategy to prepare an elastic and conductive hydrogel (ECH) of poly(vinyl alcohol) (PVA) with high content of H2SO4. The covalent cross-links formed effectively tackle the instability issue in high humidity of physically cross-linked PVA/H2SO4 hydrogels with high ionic conductivity, which were previously developed via the polymer-in-salt strategy. We systematically investigated the reaction conditions and clarified the methods to optimize the hydroxyl dehydration of PVA, resulting in excellent mechanical properties and ion conductivity simultaneously. The ECH demonstrates impressive ionic conductivity (up to 392 ± 49 mS cm-1) and elasticity (over 80% resilience upon stretching and compression after being equilibrated at various humidity levels for 24 days). Thanks to the excellent water retention of the high H2SO4 content, the ECH maintains an ionic conductivity exceeding 210 mS cm-1 for over 420 days at 50% relative humidity (RH) and retains over 100 mS cm-1 even after 3 days under extremely dry conditions (7% RH). These remarkable properties make the ECH an ideal candidate for applications requiring reliable ionic conductivity in diverse environmental conditions. Additionally, we demonstrated that the ECH can function as a stretchable Joule heater with high conformability for heating up objects with curved surfaces. The heating rate could reach a fast rate of ∼12 °C s-1 even when a human-safe alternating current voltage is below 36 V, attributed to the high ionic conductivity. We believe that the high performance and ease of fabrication make our hydrogels a promising candidate for use as electrolytes in flexible energy storage devices, electrolyte gates in electrochemical transistors, and artificial skin, which often face long-term stability challenges under varying humidity conditions.

Highly conductive and sensitive alginate hydrogel strain sensors fabricated using near-field electrohydrodynamic direct-writing process

Hydrogel flexible sensors have attracted considerable attention because of their wearability, biocompatibility, and precision signal transmission capability. However, the hydrogel strain sensors fabricated by conventional printing or hand-injection methods have difficulty balancing their mechanical strength and sensing characteristics, limiting the application of hydrogel strain sensors. Herein, polyvinyl alcohol and polyacrylamide were loosely crosslinked with sodium alginate through chemical cross-linking. Subsequently, MXene nanosheets were introduced for doping, the crosslinked hydrogel conductive network was constructed, and the hydrogel strain sensors were fabricated using the electrohydrodynamic (EHD) printing method. The ions in the EHD-printed hydrogel undergo directional movement under an externally enhanced electric field, causing the formation of more uniform and dense porous conductive networks inside the hydrogel, and high electrical conductivity (0.49 S m−1) is obtained. These hydrogel strain sensors have excellent mechanical properties (tensile strength: 0.17 MPa at 787 % strain), high sensitivity (gauge factor: 1.54 at 0–100 % strain), and low detection limits (1 % strain). Furthermore, demonstrations of real-time Morse code tapping information transmission, handwriting recognition during writing, and human physiological behavior monitoring demonstrations using the fabricated sensors indicate that the EHD-printed hydrogel strain sensor method has significant potential for wearable devices and human-computer interaction applications.

Suppression of Zinc Dendrite Growth by Enhanced Polyacrylamide Gel Electrolytes in Zinc-Ion Battery.

Aqueous zinc-ion batteries have become a promising energy storage battery due to high theoretical specific capacity, abundant zinc resources and low cost. However, zinc dendrite growth and hydrogen evolution reaction limit their application. This study aims to improve the cycling performance and stability of aqueous zinc-ion batteries by improving the gel electrolyte. Polyacrylamide (PAM) is selected as the base material of the gel electrolyte, which has good stability and safety, but the water retention capacity, Zn2+ migration number, and ionic conductivity of PAM are low, which affects the long-term stability of the battery. In response to these problems, we optimized PAM by chemical cross-linking method, and formed an enhanced PAM gel by adding disodium citrate dihydrate (SC). Experimental results show that the introduction of an appropriate amount of SC in the enhanced PAM gel electrolyte can significantly improve its electrochemical performance. The zinc-ion symmetric battery achieved a stable cycle of more than 2100 hours at a current density of 0.5 mA cm-2, which is mainly attributed to the inhibitory effect of the enhanced PAM gel on zinc dendrite growth and hydrogen evolution reaction. This study provides a new direction for the development and application of flexible zinc-ion batteries.

Polyethyleneimine assisted zeolitic imidazolate frameworks foam embed silver to enhance the uranium recovery from seawater

The powder structure, poor surface wettability and biofouling significantly limited the application potential of ZIFs (zeolitic imidazolate frameworks) in uranium extraction from seawater. Herein, a superhydrophilic polyethyleneimine assisted zeolitic imidazolate frameworks foam embed silver (CPEZ8A) was successfully prepared by simple chemical cross-linking and in-situ growth methods to explore the effects of hydrophilic matrix and silver antimicrobial agent on the uranium adsorption properties of ZIFs materials. The mechanical property and water contact angle test of CPEZ8A foam were performed to confirm its higher compression stress (with 1.314 MPa) and surface superhydrophilic. Moreover, CPEZ8A foam displayed an excellent resistance to biological attachment after 7 days in algae solution. Importantly, CPEZ8A showed the maximum U (VI) uptake capacity (775.19 mg/g) with 4.37 times of pure ZIF-8 at nearly seawater pH and retained relative high U-uptake amount during the broad pH range (4.0–9.0). Ion competition experiments were also investigated to verify the CPEZ8A foam excellent selectivity (Kd = 15,072.1 mL/g). Notably, the removal rate of CPEZ8A foam reach 81.31 % in natural seawater and remain nearly 80 % in simulated contaminated seawater. Therefore, this work provides an effective strategy to develop highly efficient ZIFs adsorbents for uranium capture.

Effective multi-biocatalyst system with reusable NADH for transformation of glycerol to value-added dihydroxyacetone

Glycerol-based biorefinery can be a highly profitable process by producing highly value-added products such as dihydroxyacetone via combined catalytic strategies. Here, two-enzyme system is adopted for the transformation of glycerol into highly valuable dihydroxyacetone as well as cofactor regeneration at the same time. Glycerol dehydrogenase (GDH) and alcohol dehydrogenase (ADH) are co-immobilized within magnetically separable and spherical mesocellular silica foam (Mag-S-MCF), to prepare NER-(GDH/ADH). In details, GDH and ADH are adsorbed into the mesopores of Mag-S-MCF, and further crosslinked within the mesopores of Mag-S-MCF. The resulting nanoscale enzyme reactors (NER) of crosslinked GDH and ADH molecules within the bottle-neck structured mesopores can effectively prevent larger sized crosslinked enzyme aggregates from being leached out of smaller mesopores, due to the bottle-neck mesopore structure of Mag-S-MCF, as well as stabilize the activity of GDH and ADH upon chemical crosslinking, effectively preventing the denaturation of enzyme molecules. More importantly, the proximity of GDH and ADH molecules within mesopores of NER improves the efficiency of cofactor-mediated dual-enzymatic reactions by relieving mass-transfer limitations and improving cofactor recycling in an effective way, expediting both glycerol oxidation and dihydroxyacetone generation at the same time. As a result, the DHA concentration of NER-(GDH/ADH) and the simple mixture of NER-GDH and NER-ADH were 410 μM and 336 μM, respectively. To the best of our knowledge, this report is the first demonstration of stabilized nanoscale multi-enzyme reactor system, equipped with efficient cofactor regeneration within confined mesopores, for efficient glycerol transformation to high-valued dihydroxyacetone.Graphical

A self-adjuvanted VLPs-based Covid-19 vaccine proven versatile, safe, and highly protective

Vaccination has played a critical role in mitigating COVID-19. Despite the availability of licensed vaccines, there remains a pressing need for improved vaccine platforms that provide high protection, safety, and versatility, while also reducing vaccine costs. In response to these challenges, our aim is to create a self-adjuvanted vaccine against SARS-CoV-2, utilizing Virus-Like Particles (VLPs) as the foundation. To achieve this, we produced bacteriophage (Qβ) VLPs in a prokaryotic system and purified them using a rapid and cost-effective strategy involving organic solvents. This method aims to solubilize lipids and components of the cell membrane to eliminate endotoxins present in bacterial samples. For vaccine formulation, Receptor Binding Domain (RBD) antigens were conjugated using chemical crosslinkers, a process compatible with Good Manufacturing Practice (GMP) standards. Transmission Electron Microscopy (TEM) confirmed the expected folding and spatial configuration of the QβVLPs vaccine. Additionally, vaccine formulation assessment involved SDS-PAGE stained with Coomassie Brilliant Blue, Western blotting, and stereomicroscopic experiments. In vitro and in vivo evaluations of the vaccine formulation were conducted to assess its capacity to induce a protective immune response without causing side effects. Vaccine doses of 20 µg and 50 µg stimulated the production of neutralizing antibodies. In in vivo testing, the group of animals vaccinated with 50 µg of vaccine formulation provided complete protection against virus infection, maintaining stable body weight without showing signs of disease. In conclusion, the QβVLPs-RBD vaccine has proven to be effective and safe, eliminating the necessity for supplementary adjuvants and offering a financially feasible approach. Moreover, this vaccine platform demonstrates flexibility in targeting Variants of Concern (VOCs) via established conjugation protocols with VLPs.

Advancements in Hydrogels for Corneal Healing and Tissue Engineering.

Hydrogels have garnered significant attention for their versatile applications across various fields, including biomedical engineering. This review delves into the fundamentals of hydrogels, exploring their definition, properties, and classification. Hydrogels, as three-dimensional networks of crosslinked polymers, possess tunable properties such as biocompatibility, mechanical strength, and hydrophilicity, making them ideal for medical applications. Uniquely, this article offers original insights into the application of hydrogels specifically for corneal tissue engineering, bridging a gap in current research. The review further examines the anatomical and functional complexities of the cornea, highlighting the challenges associated with corneal pathologies and the current reliance on donor corneas for transplantation. Considering the global shortage of donor corneas, this review discusses the potential of hydrogel-based materials in corneal tissue engineering. Emphasis is placed on the synthesis processes, including physical and chemical crosslinking, and the integration of bioactive molecules. Stimuli-responsive hydrogels, which react to environmental triggers, are identified as promising tools for drug delivery and tissue repair. Additionally, clinical applications of hydrogels in corneal pathologies are explored, showcasing their efficacy in various trials. Finally, the review addresses the challenges of regulatory approval and the need for further research to fully realize the potential of hydrogels in corneal tissue engineering, offering a promising outlook for future developments in this field.

Enhanced Organic Solvent Nanofiltration Membranes with Double Permeance via Laser‐Induced Graphitization of Polybenzimidazole

AbstractThis study investigates the fabrication of organic solvent nanofiltration (OSN) membranes through laser‐induced graphitization of polybenzimidazole (PBI). Employing a CO2 laser, the polymer is converted into graphene, resulting in controlled submicron‐scale porous 3D structures, a feat not achievable with traditional methods such as chemical crosslinking. The effectiveness of this process hinges on precise adjustments of laser parameters, such as fluence, to attain the ideal graphitization levels. The findings indicate that partial graphitization, as opposed to excessive, is crucial for preserving the membrane's microstructure and enhancing its functional properties. The partially graphitized PBI‐LIG (Polybenzimidazole ‒ Laser‐induced Graphene) membranes achieved up to 94% rejection of Congo red from ethanol, with an ethanol permeance rate of 12.14 LMH bar−1—nearly twice that of standard PBI membranes. Additionally, these membranes showcased outstanding chemical stability and solvent resistance, maintaining over 99% structural integrity and experiencing <1% weight loss after prolonged exposure to various industrial solvents over a week. These results highlight the potential of laser‐graphitized PBI membranes for applications in harsh chemical conditions, paving the way for further optimization of high‐performance OSN membranes. This research advances membrane technology, merging laser engineering with materials science, and contributes to environmental sustainability and industrial efficiency.

Lightweight, ultrahigh-strength and flame-retardant cellulose aerogel crosslinked with a reactive P/N-rich curdlan derivative

Cellulose aerogel, recognized for its eco-friendliness, bio-sustainability and excellent thermal insulation property, holds immense potential as an insulation material. However, the application of cellulose aerogel has been hindered by its inherent drawbacks, particularly its low strength and flammability. In this study, a reactive P/N-rich curdlan derivative (NT) was synthesized and characterized. Lightweight, ultrahigh-strength and flame-retardant composite aerogels were then prepared by slow freezing, freeze-drying and chemical crosslinking methods. Composite aerogel crosslinked with 30% NT exhibited exceptional thermal insulation property with a low thermal conductivity of 33.9 mW/(m·K), which rivaled the value of petroleum-based thermal insulation materials. It possessed an ultrahigh compressive modulus (0.786 MPa) at low density (21.6 mg/cm3), which supported >12,000 times its weight. It also displayed superior flame-retardant property, with a limiting oxygen index of up to 33.1% and a V-0 rating in the UL-94 test. This study provides a new insight into the high-value utilization of natural polysaccharide and an innovative solution to the problem of low strength and flammability of cellulose aerogel. Cellulose aerogels with ultrahigh strength, superior flame retardancy and thermal insulation property possess a promising application in the fields of construction, aerospace and thermal protective clothing as high-performance thermal insulation materials.

Exploring the wear resistance of EPDM‐PAE/SWCNTs composites with a novel perspective of micro‐network structure

AbstractThe effect of single‐walled carbon nanotubes (SWCNTs) on the crosslinking network structure of Ethylene Propylene Diene Monomers (EPDM)—Polyamide elastomers (PAE) is investigated in detail using Hansen Solubility Parameter (HSP) theory. Rheological method and scanning electron microscopy (SEM) are used to investigate the effect of SWCNTs on the molecular chain movement and their interaction with the filler network of EPDM‐PAE. The DIN abrasion test is conducted to obtain the effect of SWCNTs on the wear characteristics of EPDM‐PAE/SWCNTs composites. The linear synergistic relationship between crosslinking density and wear volume indicates that the change in wear properties is contributed by the micro‐network structure. The addition of SWCNTs increases the chemical crosslinking density and improves the wear properties of EPDM‐PAE. However, the decrease in the physical crosslinking density leads to an increase in the degree of internal friction within the network structure, resulting in a decrease in the wear performance. Changes in wear resistance can be related to the micro‐network structure, which provides a novel approach to studying the wear characteristics of high‐performance elastomers. It is also an innovative work based on the network structure to guide the preparation of new wear‐resistant elastomeric materials.

Effective elimination of internal phosphorus pollution with MgFe-LDHs hybrid material in eutrophic water: The chemical forms, transformation mechanism, and dynamic relationships

The internal phosphorus (P) pollution is a major cause of water eutrophication. Although the traditional powders materials, with good performance, were difficult to recycle due to its shape, and the reaction mechanism between materials and internal P was rarely elucidated. In this work, a hydrotalcite composite material (MgFe-LDHs hybrid gel microspheres) was prepared via chemical crosslinking to eliminate internal P pollution both in overlying water and sediments effectively. Benefiting from the strong coordination between iron hydroxide on the MgFe-LDHs surface and internal P, the P adsorption capacity was up to 1256.38 mg/kg under natural conditions, the IP (NaOH-P and HCl-P) and OP were 78 % and 22 %, respectively. During 40-days remediation experiment, with the addition of MgFe-LDHs hybrid gel microspheres, whatever in the mixed or the capped, promoted a conversion from stable P to soluble active P of NaOH-P in sediments, and thus contributing to an easy adsorption of NaOH-P by MgFe-LDHs hybrid gel microspheres (The NaOH-P in sediments decreased by 16 % and 22 %, respectively). Meanwhile, the excessive stable HCl-P (only a minor portion) that could not be adsorbed by MgFe-LDHs remained in the form of Ca-P in sediments. Additionally, the MgFe-LDHs hybrid gel microspheres improved the microbial community structure, and the microorganism was involved in the elimination of internal P simultaneously. In summary, this study proposed a promising remediation approach to resolve the problem of internal P pollution in eutrophic water with high efficiency, cost-effective, and environmentally friendly.

Dual-Self-Crosslinking Effect of Alginate-Di-Aldehyde with Natural and Synthetic Co-Polymers as Injectable In Situ-Forming Biodegradable Hydrogel.

Injectable, in situ-forming hydrogels, both biocompatible and biodegradable, have garnered significant attention in tissue engineering due to their potential for creating adaptable scaffolds. The adaptability of these hydrogels, made from natural proteins and polysaccharides, opens up a world of possibilities. In this study, sodium alginate was used to synthesize alginate di-aldehyde (ADA) through periodate oxidation, resulting in a lower molecular weight and reduced viscosity, with different degrees of oxidation (54% and 70%). The dual-crosslinking mechanism produced an injectable in situ hydrogel. Initially, physical crosslinking occurred between ADA and borax via borax complexation, followed by chemical crosslinking with gelatin through a Schiff's base reaction, which takes place between the amino groups of gelatin and the aldehyde groups of ADA, without requiring an external crosslinking agent. The formation of Schiff's base was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. At the same time, the aldehyde groups in ADA were characterized using FT-IR, proton nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC), which determined its molecular weight. Furthermore, borax complexation was validated through boron-11 nuclear magnetic resonance (¹¹B NMR). The hydrogel formulation containing 70% ADA, polyethylene glycol (PEG), and 9% gelatin exhibited a decreased gelation time at physiological temperature, attributed to the increased gelatin content and higher degree of oxidation. Rheological analysis mirrored these findings, showing a correlation with gelation time. The swelling capacity was also enhanced due to the increased oxidation degree of PEG and the system's elevated gelatin content and hydrophilicity. The hydrogel demonstrated an average pore size of 40-60 µm and a compressive strength of 376.80 kPa. The lower molecular weight and varied pH conditions influenced its degradation behavior. Notably, the hydrogel's syringeability was deemed sufficient for practical applications, further enhancing its potential in tissue engineering. Given these properties, the 70% ADA/gelatin/PEG hydrogel is a promising candidate and a potential game-changer for injectable, self-crosslinking applications in tissue engineering. Its potential to revolutionize the field is inspiring and should motivate further exploration.

Polyethylenimine functionalized graphene oxide and cellulose nanofibril composite hydrogels: Synthesis, characterization and water pollutants adsorption

A stable 2,2,6,6-tetramethylpiperidine-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibril (TCNF)/graphene oxide (GO)/polyethylenimine (PEI) composite hydrogel was synthesized by self-assembly instead of chemical crosslinking. Their chemical, morphology, surface, and mechanical properties were characterized and adsorption behavior for methyl blue (–) was systematically investigated in terms of the optimal GO content, pH effect, kinetics, and isotherm models. Additionally, to assess the adsorption capability of the TCNF/GO/PEI hydrogel for various contaminants, its effectiveness was also tested for methylene blue (+), Cu (II), and soybean oils. The maximum adsorption capability for the methyl blue (−) dyes increased from 3125 to 3962 mg/g when 13.3 % of GO was added. The adsorption capability for Cu (II) and soybean oils rose from 205.3 to 218.5 and 2.1 to 7.2 mg/g, respectively. The adsorption capability of optimized TCNF/GO/PEI hydrogel for a variety of contaminants was improved overall based on the increase of surface area, electrostatic interactions, and hydrophobic domains. Moreover, adding GO did not impact the adsorption mechanism but increased the external diffusion rate in the intraparticle diffusion model. This work provides a self-assembling route to TCNF/GO/PEI hydrogels with great potential for the removal of multiple water pollutants.

Preparation and slow-release properties of nanocellulose composite hydrogels

Nanocellulose (CNF) was obtained from carrots using a combination of chemical treatment, mechanical milling, and ultrasonic treatment. Ultrafast preparation of maleic anhydride esterified nanocellulose was achieved by a hydrated hydrogen ion-driven dissociation, chemical cross-linking strategy based on a “one-pot” reaction method. Esterification modification with maleic anhydride reduced the crystallinity of nanocellulose and enhanced its thermal stability. High-strength drug-carrying hydrogels (MACNF/SA) with different drug loading capacities were prepared using cefixime (CFX) as a drug model and maleic anhydride esterified nanocellulose (MACNF) and sodium alginate (SA) as the main raw materials. The compressive strength of MACNF/SA hydrogels made from MACNF reached a maximum of 80.3 kPa when the mass ratio of CNF to MA was 2.5:12. Rheological property tests showed that the MACNF/SA hydrogels were pseudoplastic fluids with shear thinning. The drug release from the drug-carrying hydrogels followed non-Fickian diffusion.

Sodium alginate-g-polyacrylamide hydrogel for water retention and plant growth promotion in water-deficient soils

Natural polymer-based hydrogels are preferred as soil water retention agents due to their inherent biocompatibility and biodegradability. Generally, these natural polymers are chemically modified by graft polymerization of vinyl monomers to improve their water absorption and retention properties. Among the polysaccharides used to prepare natural hydrogels, those based on sodium alginate (Alg) stand out for their high-water absorption and retention capacity, as well as for their ability to promote plant growth. The main objective of this study was to develop a biodegradable alginate-based hydrogel as a water retainer to promote plant growth under water deficit conditions. The synthesis was achieved by grafting poly(acrylamide) (PAM) onto Alg backbone, using bisacrylamide as chemical crosslinker and different ratios of alginate:acrylamide (Ac). In addition, Eucalyptus nitens seedlings were used as a model plant to evaluate the effect of alginate-g-polyacrylamide (Alg:PAM) hydrogel application to the growing medium on plant survival, growth, and physiological responses under both well-watered and water-deficient soil conditions. The maximum degree of swelling (65 g/g) was obtained for the hydrogel prepared. The pseudo-second order model described the water uptake kinetics of the hydrogel. The degradability of Alg:PAM hydrogel reached up to 85 % in 5 weeks in soil and occurs by breaking the glycosidic bonds of the alginate. The E. nitens seedlings cultivated with different doses of Alg:PAM hydrogel (4:1 Alg:Ac) showed higher values of height and root diameter relative growth, survival and photosynthetic responses in comparison to non-treated plants. The results indicate that Alg:PAM hydrogel (4:1 Alg:Ac) has promising applications in forestry as a water retention and seedling growth promoter under water deficient conditions.

Evaluation of a Kenaf Nanocrystalline Cellulose-based Hydrogel Containing Platelet Lysate for Full-thickness Wound Healing

Introduction: Healing full-thickness wounds is often challenging and time-consuming, with complications such as scarring and infections. The standard treatment, split skin grafting, has limitations due to the availability of healthy donors and suitability for immunocompromised patients. Method: Autologous platelet lysate (PL) has been popular for tissue regenerative potential because it contains growth factors (GF) and is a safer option for bedridden patients with weak immune systems. However, PL has inconsistent clinical efficacy, high costs, and a short half-life. To address these issues, this study explores a novel delivery system by fabricating a chitosan/nanocrystalline cellulose (CS/NCC) hydrogel to sustainably deliver autologous PL to the wound site. Notably, NCC was prepared from kenaf bast fibers using acid hydrolysis and integrated into the CS matrix through physical entrapment without any chemical crosslinkers. The composite hydrogel was then enriched with autologous PL and further characterized for its physicochemical properties, in vitro GF release, and compatibility with skin cells. At the molecular level, gene expression of wound healing genes was facilitated using qPCR, revealing that the PL-supplemented hydrogel upregulated the expression of extracellular matrix genes. An in vivo study using a full-thickness wound model demonstrated that the CS-NCC-PL hydrogel dressing achieved 81.8% wound closure within 14 days, compared to the control groups. Result: Histological analysis indicated enhanced re-epithelialization, angiogenesis, and collagen deposition. Particularly, the CS-NCC-PL hydrogel group showed a significantly higher hydroxyproline content (60.62 ± 11.46 μg/100 mg) by day 14. Immunohistochemistry results revealed elevated levels of α-SMA and CD31, markers of myofibroblast presence and angiogenesis, peaking at day 7. Conclusion: These findings suggest that the CS-NCC-PL hydrogel is a promising personalized wound dressing for bedridden patients, offering improved healing outcomes in hospital settings.

Fabrication and characterization of electrospun core-shell nanofibers of bilayer zein/pullulan emulsions crosslinked by genipin

In this study, the electrospun core-shell nanofibers of zein/pullulan stabilized bilayer emulsions before and after genipin crosslinking were fabricated. The experimental results indicated that the addition of pullulan increased the apparent viscosity and elastic modulus of the bilayer emulsions, which was further increased after the chemical crosslinking of genipin. The nanofiber diameter increased from 102.9 nm to 169.9 nm with the increasing ratio of pullulan, but increased significantly to a range of 405.6–708.0 nm after genipin crosslinking. The electrospun nanofiber films of crosslinked emulsions had higher thermal stability and stronger water stability. The FTIR result proved the existence of hydrogen bond interaction between the zein, pullulan, and genipin molecules. In addition, before and after crosslinking, the encapsulation efficiency of electrospun fiber films for camellia oil was >77.68 %, and the maximum encapsulation efficiency could reach 87.94 %, and there was no significant change during the 7-day storage period, showing good stability. These research results can provide a theoretical basis for the encapsulation of hydrophobic active substances in zein-based emulsion electrospun core-shell nanofibers.