Search Results (326)

Paper-based artworks are prone to natural aging processes driven by chemical and biological processes. Numerous treatments have been developed to mitigate deterioration and prevent irreversible damage. In this study, we investigated the use of poly(acrylic acid)/TiO₂ composite hydrogels, combining their cleaning and protective functions in a minimally invasive treatment. Hydrogels allow for controlled water flow and photocatalytic TiO₂ nanoparticles enhance the hydrogel’s efficacy by enabling the removal of oxidation products and inactivating biological contaminants. Furthermore, this innovative material can act as a protective coating against UV-induced aging, preserving both color and stability of the paper. Raman spectroscopy and confocal laser scanning microscopy imaging techniques were employed to evaluate the treatments, allowing for us to differentiate between hydrolytic and oxidative aging processes. Our findings demonstrate that papers coated with poly(acrylic acid)/TiO₂ composite hydrogels exhibit significant reductions in oxidative markers, an enhanced color stability, and an overall improved resistance to degradation compared to uncoated samples. Full article

The application of nanocomposites based on polyacrylamide hydrogels as well as silica nanoparticles in various tasks related to the petroleum industry has been rapidly developing in the last 10–15 years. Analysis of the literature has shown that the introduction of nanoparticles into hydrogels significantly increases their structural and mechanical characteristics and improves their thermal stability. Nanocomposites based on hydrogels are used in different technological processes of oil production: for conformance control, water shutoff in production wells, and well killing with loss circulation control. In all these processes, hydrogels crosslinked with different crosslinkers are used, with the addition of different amounts of nanoparticles. The highest nanoparticle content, from 5 to 9 wt%, was observed in hydrogels for well killing. This is explained by the fact that the volumes of injection of block packs are counted only in tens of cubic meters, and for the sake of trouble-free workover, it is very important to preserve the structural and mechanical properties of block packs during the entire repair of the well. For water shutoff, the volumes of nanocomposite injection, depending on the well design, are from 50 to 150 m³. For conformance control, it is required to inject from one to several thousand cubic meters of hydrogel with nanoparticles. Naturally, for such operations, service companies try to select compositions with the minimum required nanoparticle content, which would ensure injection efficiency but at the same time would not lose economic attractiveness. The aim of the present work is to develop formulations of nanocomposites with increased structural and mechanical characteristics based on hydrogels made of partially hydrolyzed polyacrylamide crosslinked with resorcinol and paraform, with the addition of commercially available nanosilica, as well as to study their thermal degradation, which is necessary to predict the lifetime of gel shields in reservoir conditions. Hydrogels with additives of pyrogenic (HCSIL200, HCSIL300, RX380) and hydrated (white carbon black grades: ‘BS-50’, ‘BS-120 NU’, ‘BS-120 U’) nanosilica have been studied. The best samples in terms of their structural and mechanical properties have been established: nanocomposites with HCSIL200, HCSIL300, and BS-120 NU. The addition of hydrophilic nanosilica HCSIL200 in the amount of 0.4 wt% to a hydrogel consisting of partially hydrolyzed polyacrylamide (1%), resorcinol (0.04%), and paraform (0.09%) increased its elastic modulus by almost two times and its USS by almost three times. The thermal degradation of hydrogels was studied at 140 °C, and the experimental time was converted to the exposure time at 80 °C using Van’t Hoff’s rule. It was found that the nanocomposite with HCSIL200 retains its properties at a satisfactory level for 19 months. Filtration studies on water-saturated fractured reservoir models showed that the residual resistance factor and selectivity of the effect of nanocomposites with HCSIL200 on fractures are very high (226.4 and 91.6 for fracture with an opening of 0.05 cm and 11.0 for porous medium with a permeability of 332.3 mD). The selectivity of the isolating action on fractured intervals of the porous formation was noted. Full article

Biomass valorization and bio-based material development are of major research interest following the spirit of the circular economy. Aloe vera cultivation is a widespread agricultural activity oriented toward supplement production because of its well-known antioxidant and antimicrobial properties. Aloe vera juice production also produces a large amount of biomass byproducts that are usually landfilled. On the other hand, cellulose nanocrystals are widely used in several applications, such as biomaterials, bio-compatible polymers, nanocomposites, food packaging, medicines, cosmetics, and sensors, due to their unique physical, mechanical, optical, electrical, and healing properties as well as their compatibility with biological tissues. This study introduces a novel approach combining the microwave-assisted extraction (MAE) of cellulose from this residue with the subsequent isolation of cellulose nanocrystals (CNCs). The MAE process, which exhibits a rapid heating and penetrating ability, was optimized to maximize the cellulose yield under various conditions (microwave power, solvent ratio, and time). Analysis using FTIR, XRD, SEM, and DMA indicated that isolated pure cellulose nanocrystals and a stable PVA–CNC porous hydrogel network were produced. The PVA–CNC hydrogel was synthesized to enable the formation of a semi-crystalline network that imparts the material with enhanced mechanical properties. Both final products of this study could potentially be used for various applications. Full article

Series of composites containing 2.5–17.0% Ag and consisting of spherical silver nanoparticles with sizes ranging from 5.1 to 18.3 nm and from 6.4 to 21.8 nm for GM- and κ-CG-based composites, respectively, were prepared using the reducing and stabilizing ability of the natural polysaccharides galactomannan (GM) and κ-carrageenan (κ-CG). The antiradical activity of the obtained composites was evaluated using the decolorization of ABTS+^· solution. It was found that the IC₅₀ value of a composite’s aqueous solution depends on the type of stabilizing ligand, the amount of inorganic phases, and the average size of AgNPs, and varies in the range of 0.015–0.08 mg·mL⁻¹ and 0.03–0.59 mg·mL⁻¹ for GM-AgNPs − κ-CG-AgNPs composites, respectively. GM-AgNPs − κ-CG-AgNPs hydrogels were successfully prepared and characterized on the basis of composites containing 2.5% Ag (demonstrating the most pronounced antiradical activity in terms of IC₅₀ values per mole amount of Ag). It was found that the optimal ratio of composites that provided the best water-holding capacity and prolonged complete release of AgNPs from the hydrogel composition was 1:1. The influence of Ca²⁺ cations on the co-gel formation of the GM-AgNPs − κ-CG-AgNPs system, as well as the expression of their water-holding capacity and the rate of AgNPs release from the hydrogel carrier, was evaluated. Full article

The use of glycerolates of biogenic elements as biocompatible precursors in sol–gel synthesis is an innovative direction and opens up new scientific and practical prospects in chemistry and technology of producing practically important biomedical materials, including hemostatic, antimicrobial, and wound healing materials. Using biocompatible precursors, silicon, zinc, boron, and iron glycerolates, new bioactive nanocomposite hydrogels were obtained by the sol–gel method. The composition and structural features of the hydrogels were studied using a complex of modern analytical techniques, including TEM, XRD, AES, and ESI MS. Hemostatic activity of the hydrogels was studied in the in vivo experiments; using the example of silicon-iron-zinc-boron glycerolates hydrogel, primary toxicological studies were carried out. Antimicrobial properties of hydrogels were studied using the agar diffusion method. The structural features of hydrogels and their relationship to medical and biological properties were revealed. It was shown that glycerolates hydrogels are non-toxic, and exhibit pronounced hemostatic activity, generally comparable to the commercial hemostatic drug Capramine. Antimicrobial activity is more pronounced for silicon-iron-zinc-boron and silicon-iron-boron glycerolates gel. The results obtained indicate that these glycerolates hydrogels are potential hemostatic and antibiotic-independent antimicrobial agents for topical wound healing applications in medical and veterinary practice. Full article

Hydrogel nanocomposites that respond to external stimuli and possess switchable electrical properties are considered as emerging materials with potential uses in electrical, electrochemical, and biological devices. This work reports the synthesis and characterization of thermo-responsive and electroconductive hydrogel nanocomposites based on poly(N-isopropylacrylamide) (PNiPAAm) and gold nanoparticles (nanospheres—AuNPs and nanorods—AuNRs) using two different synthetic techniques. Method I involved γ-irradiation-induced crosslinking of a polymer matrix (hydrogel), followed by radiolytic in situ formation of gold nanoparticles, while Method II included the chemical synthesis of nanoparticles, followed by radiolytic formation of a polymer matrix around the gold nanoparticles. UV–Vis spectral studies revealed the presence of local surface plasmon resonance (LSPR) bands characteristic of nanoparticles of different shapes, confirming their formation and stability inside the polymer matrix. Morphological, structural, and physicochemical analyses indicated the existence of a stable porous polymer matrix, the formation of nanoparticles with a face-centered cubic structure, increased swelling capacity, and a slightly higher volume phase transition temperature (VPTT) for the hydrogel nanocomposites. Comparative electrochemical impedance spectroscopy (EIS) showed an increase in conductivity for the nano Au-PNiPAAm hydrogel nanocomposites compared to the PNiPAAm hydrogel, with a considerable rise detected above the VPTT. By reverting to room temperature, the conductivity decreased, indicating that the investigated hydrogel nanocomposites exhibited a remarkable reversible “on–off” thermo-switchable mechanism. The highest conductivity was observed for the sample with rod-shaped gold nanoparticles. The research findings, which include optical, structural, morphological, and physicochemical characterization, evaluation of the efficiency of the chosen synthesis methods, and conductivity testing, provide a starting point for future research on the given nanocomposite materials with integrated multifunctionality. Full article

This study presents the synthesis, characterization, and evaluation of hybrid hydrogels based on calcium alginate (Ca-Alg) and synthetic nanoclay LaponiteRD (Lap), with an emphasis on their swelling and sorption properties. The motivation behind the development of these hybrid hydrogels stems from the need for sustainable materials with enhanced mechanical strength, swelling properties, and sorption capacity for environmental remediation and controlled-release applications. Synthesis methods for the ionotropically cross-linked Ca-Alg hydrogel and Alg–Lap composite hydrogels, based on Alg and Lap in the form of granules and fibres, have been developed. The Fourier-transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses of composite hydrogels confirmed the successful incorporation of Lap into the Ca-Alg matrix, indicating strong interactions between the polymer and clay, which enhanced the structural integrity of the hydrogels. The morphology of the surface and pore structure of nanocomposites were studied using Scanning Electron Microscopy (SEM). The swelling behaviour of the nanocomposites was largely dependent on the concentrations of Lap and the cross-linking agent (CaCl₂), with higher concentrations leading to more rigid, less swellable structures due to the increased cross-linking density. The sorption studies, specifically with Fe(II) ions, demonstrated that the hybrid hydrogels possess a large sorption capacity, with Lap contributing to selective sorption at lower Fe(II) ion concentrations and Alg enhancing overall capacity at higher concentrations. This suggests that the synergistic interaction between Alg and Lap not only improves mechanical stability but also tailors the sorption properties of the hydrogels. These findings position the Alg-Lap hydrogels as promising materials for a range of environmental applications, including wastewater treatment, heavy metal ion removal, and the design of advanced filtration systems. The study’s insights into the tunability of these hydrogels pave the way for further research into their use in diverse fields such as biomedicine, agriculture, and industrial water management. Full article

In recent years, the development of multifunctional hydrogels has gained significant attention due to their potential in various biomedical applications, including antimicrobial, antioxidant, and anticancer therapies. By integrating biocompatible polymers and nanoparticles, these hydrogels can achieve enhanced activity and targeted therapeutic effects. In this study, carrageenan/2-dimethyl aminoethyl methacrylate/gelatin (CAR/DEMA/Gelt) composite hydrogel was synthesized using microwave radiation specifically for its efficiency in enhancing cross-linking and promoting uniform nanoparticle dispersion within the matrix. Zinc oxide (ZnO) nanoparticles were incorporated into the hydrogel to form the (CAR/DEMA/Gelt/ZnO) nanocomposite. The hydrogels were characterized using FT-IR, FE-SEM, XRD, TGA, and EDX, confirming successful cross-linking and structural integrity. The nanocomposite hydrogel exhibited more enhanced antimicrobial activity than the composite hydrogel against Gram-positive Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis), with inhibition zones of 15 mm and 16 mm, respectively, while in case of the Gram-negative bacteria, Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli), the inhibition zones were 29 mm and 19 mm, respectively. In addition to the unicellular fungi, Candida albicans (C. albicans), the inhibition zone was 19 mm. Moreover, the nanocomposite showed anti-inflammatory activity comparable to those of Indomethacin and antioxidant activity, with an impressive IC₅₀ value of 33.3 ± 0.05 µg/mL. In vitro cytotoxicity assays revealed significant anticancer activity. Against the MCF-7 breast cancer cell line, the CAR/DEMA/Gelt/ZnO nanocomposite showed 72.5 ± 0.02% cell viability, which decreased to 30.8 ± 0.01% after loading doxorubicin (DOX). Similarly, against the HepG2 liver cancer cell line, the free nanocomposite displayed 59.9 ± 0.006% cell viability, which depleted to 29.9 ± 0.005% when DOX was uploaded. This CAR/DEMA/Gelt/ZnO nanocomposite hydrogel demonstrates strong potential as a multifunctional platform for targeted biomedical applications, particularly in cancer therapy. Full article

Carbon-based polymeric nanocomposite hydrogels (NCHs) represent a groundbreaking advancement in biomedical materials by integrating nanoparticles such as graphene, carbon nanotubes (CNTs), carbon dots (CDs), and activated charcoal (AC) into polymeric matrices. These nanocomposites significantly enhance the mechanical strength, electrical conductivity, and bioactivity of hydrogels, making them highly effective for drug delivery, tissue engineering (TE), bioinks for 3D Bioprinting, and wound healing applications. Graphene improves the mechanical and electrical properties of hydrogels, facilitating advanced tissue scaffolding and drug delivery systems. CNTs, with their exceptional mechanical strength and conductivity, enhance rheological properties, facilitating their use as bioinks in supporting complex 3D bioprinting tasks for neural, bone, and cardiac tissues by mimicking the natural structure of tissues. CDs offer fluorescence capabilities for theranostic applications, integrating imaging and therapeutic functions. AC enhances mechanical strength, biocompatibility, and antibacterial effectiveness, making it suitable for wound healing and electroactive scaffolds. Despite these promising features, challenges remain, such as optimizing nanoparticle concentrations, ensuring biocompatibility, achieving uniform dispersion, scaling up production, and integrating multiple functionalities. Addressing these challenges through continued research and development is crucial for advancing the clinical and industrial applications of these innovative hydrogels. Full article

Exosome-integrated hydrogels represent a promising frontier in bone tissue engineering, leveraging the unique biological properties of exosomes to enhance the regenerative capabilities of hydrogels. Exosomes, as naturally occurring extracellular vesicles, carry a diverse array of bioactive molecules that play critical roles in intercellular communication and tissue regeneration. When combined with hydrogels, these exosomes can be spatiotemporally delivered to target sites, offering a controlled and sustained release of therapeutic agents. This review aims to provide a comprehensive overview of the recent advancements in the development, engineering, and application of exosome-integrated hydrogels for bone tissue engineering, highlighting their potential to overcome current challenges in tissue regeneration. Furthermore, the review explores the mechanistic pathways by which exosomes embedded within hydrogels facilitate bone repair, encompassing the regulation of inflammatory pathways, enhancement of angiogenic processes, and induction of osteogenic differentiation. Finally, the review addresses the existing challenges, such as scalability, reproducibility, and regulatory considerations, while also suggesting future directions for research in this rapidly evolving field. Thus, we hope this review contributes to advancing the development of next-generation biomaterials that synergistically integrate exosome and hydrogel technologies, thereby enhancing the efficacy of bone tissue regeneration. Full article

Today, hydrogel dressings that can protect injury sites and effectively promote healing have become highly desirable in wound management. Therefore, multifunctional silver-poli(N-isopropylacrylamide/itaconic acid) (Ag-P(NiPAAm/IA)) hydrogel nanocomposites were developed for potential application as topical treatment dressings. The radiolytic method, used for the crosslinking of the polymer matrix as well as for the in situ incorporation of silver nanoparticles (AgNPs) into the polymer matrix, enables the preparation of hydrogel nanocomposites without introducing harmful and toxic agents. Moreover, materials produced using γ-irradiation are simultaneously sterilized, thus fulfilling one of the basic requirements regarding their potential biomedical applications. The NiPAAm/IA ratio and the presence of AgNPs influenced the microstructural parameters of the investigated systems. Increasing the IA content leads to the formation of a more porous polymer matrix with larger pores, while the incorporated AgNPs act as additional junction points, decreasing the porosity and pore size of the resulting nanocomposite hydrogels. Swelling studies showed that most investigated systems uptake the fluids from their surroundings by non-Fick diffusion. Further, the Ag⁺ ion release, antibacterial activity, and cytotoxicity of Ag-P(NiPAAm/IA) hydrogel nanocomposites were examined to evaluate their biomedical potential. All hydrogel nanocomposites showed an initial burst release of Ag⁺ ions (useful in preventing bacteria adherence and biofilm formation), followed by a slower release of the same (ensuring sterility for longer use). An antibacterial activity test against Escherichia coli and Staphylococcus aureus showed that Ag-P(NiPAAm/IA) hydrogel nanocomposites, with silver concentrations around 10 ± 1 ppm, successfully prevent bacterial growth. Finally, it was shown that the investigated hydrogel nanocomposites do not exhibit a cytotoxic effect on human keratinocyte HaCaT cells. Therefore, these multifunctional hydrogel nanocomposites may promote wound repair and show promising potential for application as functional wound dressing. Full article

Photochromic inks have shown disadvantages, such as poor durability and high cost. Self-healable hydrogels have shown photostability and durability. Herein, a viologen-based covalent polymer was printed onto a paper surface toward the development of a multi-stimuli responsive chromogenic sheet with thermochromic, photochromic, and vapochromic properties. Viologen polymer was created by polymerizing a dialdehyde-based viologen with a hydroxyl-bearing dihydrazide in an acidic aqueous medium. The viologen polymer was well immobilized as a colorimetric agent into a polyvinyl alcohol (PVA)/tricarboxy cellulose (TCC)-based self-healable hydrogel. The viologen/hydrogel nanocomposite films were applied onto a paper surface. The coloration measurements showed that when exposed to ultraviolet light, the orange layer printed on the paper surface switched to green. The photochromic film was used to develop anti-counterfeiting prints using the organic hydrogel composed of a PVA/TCC composite and a viologen polymer. Reversible photochromism with strong photostability was observed when the printed papers were exposed to UV irradiation. A detection limit was monitored in the range of 0.5–300 ppm for NH_3(aq). The exposure to heat (70 °C) was found to reversibly initiate a colorimetric change. Full article

Surgical resection is the primary treatment for melanoma; however, preventing tumor recurrence after resection remains a significant clinical challenge. To address this, we developed a multifunctional nanocomposite hydrogel (H-CPG) composed of glucose oxidase (GOx)-coated CuS@PDA@GOx (CPG) nanoparticles, aminated hyaluronic acid (HA-ADH), and oxidized rhizomatous polysaccharides (OBSP), which are interconnected through hydrogen bonds and dynamic Schiff base linkages. In the acidic tumor micro-environment, the hydrogel releases GOx, catalyzing the production of hydrogen peroxide (H₂O₂), which enhances chemokinetic activity through a Cu²⁺-mediated Fenton-like reaction. This process generates hydroxyl radicals that intensify oxidative stress and promote macrophage polarization from the M2 to M1 phenotype. This polarization triggers the release of pro-inflammatory cytokines, thereby inhibiting tumor recurrence. Additionally, the hydrogel induces photothermal effects that help eradicate residual bacteria at the wound site. Overall, the H-CPG hydrogel offers a dual mechanism to prevent melanoma recurrence and reduce resistance to monotherapy, presenting a promising strategy for postoperative tumor management. Full article

Stimuli-responsive nanocomposite gels combine the unique properties of hydrogels with those of nanoparticles, thus avoiding the suboptimal results of single components and creating versatile, multi-functional platforms for therapeutic and diagnostic applications. These hybrid materials are engineered to respond to various internal and external stimuli, such as temperature, pH, light, magnetic fields, and enzymatic activity, allowing precise control over drug release, tissue regeneration, and biosensing. Their responsiveness to environmental cues permits personalized medicine approaches, providing dynamic control over therapeutic interventions and real-time diagnostic capabilities. This review explores recent advances in stimuli-responsive hybrid gels’ synthesis and application, including drug delivery, tissue engineering, and diagnostics. Overall, these platforms have significant clinical potential, and future research is expected to lead to unique solutions to address unmet medical needs. Full article

This study analyzed the effect of cellulose derivatives, namely methylcellulose (MC) and carboxymethylcellulose (CMC), on the stability of zeolite in a polymeric solution that would synthesize a three-dimensional network of poly(methacrylic acid)-co-polyacrylamide (PMAA-co-PAAm). Additionally, it investigated the effect of pH on the release of paraquat (PQ) and difenzoquat (DFZ) herbicides. Similar to previous studies with hydrogels containing CMC, the presence of bi and trivalent salts, such as Ca⁺² and Al⁺³, also drastically reduced their swelling degree from 6.7 g/g in NaCl (0.15 mol·L⁻¹) to 2.1 g/g in an AlCl₃ solution (0.15 mol·L⁻¹) for the MC nanocomposite. The viscosity results may suggest that the formation of a polysaccharide-zeolite complex contributed to the zeolite stabilization. As for the adsorption results, all samples adsorbed practically the entire concentration of both herbicides in an aqueous solution. Finally, it was also observed that the valence of the salts and molecular weight of the herbicide affect the release process, where DFZ was the herbicide with the highest concentration released. Both nanostructured hydrogels with CMC and MC exhibited lower release at pH = 7.0. These results demonstrated that a more in-depth evaluation of the phenomena involved in the application of these materials in controlled-release systems could help mitigate the impact caused by pesticides. Full article