Biomedical applications of hydrogels: A review of patents and commercial products

Engineering a bacterial polysaccharide-based metal-organic framework-enhanced bioactive 3D hydrogel for accelerated full-thickness wound healing

Hydrogels offer numerous advantages in wound healing, making them a promising alternative to traditional wound dressings. Their biocompatibility and high water content closely resemble natural biological tissues, creating a moist environment that accelerates cell proliferation and tissue repair. Hydrogels maintain optimal hydration levels, preventing wound desiccation and promoting faster healing. Furthermore, their ability to incorporate and deliver therapeutic agents such as antibiotics, anti-inflammatory drugs, or growth factors provides a multifunctional platform for enhanced wound care. Despite these advantages, current clinical wound-dressing materials often fall short in addressing the complexities of wound healing. Hydrogels, with their customizable properties and potential for integration with emerging technologies, represent a significant opportunity to overcome these limitations and improve clinical outcomes in wound management. Herein, we developed a multi-functional Cu-MOF and tannic acid-enriched polymeric hydrogel dressing composed of gellan-gum/zein for full-thickness wound repair. The physical interactions, including electrostatic interaction and hydrogen bonding between the hydrogel components, form a stable hydrogel matrix. The hydrogel exhibits antioxidant properties and antibacterial activity, and is hemocompatible and biocompatible against L929 fibroblast cells. Furthermore, the fabricated hydrogel dressing improvised a full-thickness wound-healing process in rats. Only 1.6% of the wound area was remaining in the case of GG-Z-TA/M1-treated full-thickness wounds in rats. Histopathology images suggest the Cu-MOF-loaded hydrogels aided in extensive re-epithelialization, neovascularization, and hair follicle formation to accelerate the wound-healing process.

Advancement on heparin-based hydrogel/scaffolds in biomedical and tissue engineering applications: Delivery carrier and pre-clinical implications

The advancement of biomaterials utilization in biomedical and tissue regenerative applications has emerged progressively. Hydrogels are three-dimensional, hydrophilic polymeric networks that replicate the natural extracellular matrix (ECM), establishing a hydrated porous milieu that emulates biological functions such as proliferation and differentiation of cellular components. The application of biological macromolecules, particularly Heparin-based hydrogel, has garnered considerable interest owing to various intrinsic biological and mechanical properties. This comprehensive review paper is designed to elucidate the derivation of heparin and its purification method for biomedical uses. The article briefly outlines the diverse physiochemical and biological properties of heparin derivative-based hydrogels/scaffolds and emphasizes their significance as vehicles for growth factors, genes, and cells in complex biomedical and tissue engineering applications. This publication also summarizes the potential concerns associated with heparin-based derivatives, efforts to address these issues, and current clinical perspectives. This represents the inaugural instance of an extensive summarization of heparin-based hydrogels in biomedical applications, emphasizing pre-clinical and clinical investigations, which will further assist the scientific community in addressing the challenges associated with heparin-based hydrogels in biomedical contexts.

In vitro, genomic characterization and pre-clinical evaluation of a new thermostable lytic Obolenskvirus phage formulated as a hydrogel against carbapenem-resistant Acinetobacter baumannii

The urgent threat of carbapenem-resistant Acinetobacter baumannii (CRAB) necessitates the development of new antimicrobial strategies. Bacteriophage (phage) therapy is one of the most promising alternative strategies that can be implemented to combat multidrug-resistant (MDR) bacterial infections. Herein, an A. baumannii phage VB_AB_Acb75 that exhibited lytic activity against 6 CRAB isolates (21.43%) with stability at up to 70 °C, pH 2-12, and high concentrations of organic solvents was isolated and characterized. The transmission electron microscope (TEM) detected a tailed phage with an icosahedral head and contractile tail (myoviral morphotype). The Oxford nanopore sequencing results showed an A. baumannii phage genome size of 45,487 bp, a G + C content of 38%, and 42 open reading frames (ORFs). The phylogenetic analysis, ORF, and TEM analysis indicated that A. baumannii phage VB_AB_Acb75 belongs to a novel species in the Obolenskvirus genus. Furthermore, the phage-loaded Carbopol 940 hydrogel was preclinically evaluated for wound healing effectiveness in the burn-wound animal model infected with the CRAB isolate. The histology findings showed a marked improvement in wound healing through a thick epidermal layer and the formation of well-organized fibrous connective tissue covered by a scab at the site of injury, as well as the ability to eliminate CRAB infection, as compared to the control group. In conclusion, based on in vitro, physicochemical properties, and preclinical findings, the phage-loaded hydrogel is expected to be a promising candidate for clinical evaluation against CRAB-associated skin infections.

Design and 3D Printing of Soft Orthokeratology Lenses

The effectiveness of hard orthokeratology (OK) lenses in controlling myopia has been confirmed in clinical practice. However, there exist defects including wear discomfort, limited regulation of mechanical properties and geometry, and effectiveness inconsistency with the expected efficacy. Herein, we analyze the relationship between the mechanical properties of OK lenses and the vertex displacement of the human cornea through the finite element model. It is noted that the expected corneal deformation of 15-20 μm can be achieved by soft OK lenses with an elasticity modulus above 9 MPa, which is far lower than the 2.7 GPa of commercial OK lenses. No obvious displacement difference occurred when the elasticity modulus of the OK lenses exceeded 200 MPa. Thus, we propose the hypothesis of soft OK lenses based on hydrogel materials for controlling myopia. The soft OK lenses are fabricated by a two-step 3D printing technology using a multicomponent bioink containing methyl methacrylate, hydroxyethyl methacrylate, polyethylene glycol diacrylate, and 3-(trimethoxysilyl)propyl methacrylate (KH-570). The printed OK lenses possess comfort wear, high light transmittance, smooth surface, regulated elasticity modulus (from 33 to 535 MPa) and geometry, and excellent biocompatibility. Additionally, the effectiveness of soft OK lenses is confirmed through a porcine corneal model with obvious corneal deformation comparable to that of the commercial ones. This study demonstrates the feasibility of soft OK lenses for controlling myopia and provides support for the design and fabrication of soft OK lenses for comfortable wear.

Injectable nanocomposite hydrogels for targeted intervention in cancer, wound healing, and bone and myocardial tissue engineering

Despite current medicine's fast-paced advances, many acute and chronic illnesses still lack truly effective and safe therapies. Cancer treatments often lead to off-target healthy tissue damage and poor therapeutic outcomes, wound standard treatments generally demonstrate poor healing efficacy and increased susceptibility to infection, and bone tissue engineering and myocardial tissue engineering can result in immunological rejection and limited availability. To tackle these issues, injectable hydrogels have emerged, and through the incorporation of nanoparticles, nanocomposite hydrogels have appeared as versatile platforms, offering improved biocompatibility, mechanical strength, stability, and precise controlled drug release, as well as targeted delivery with increased drug retention at the site of action, reducing systemic drug distribution to non-target sites. With the ability to deliver a diverse range of therapeutic entities, including low molecular weight drugs, proteins, antibodies, and even isolated cells, injectable nanocomposite hydrogels have revolutionized current therapies, working as multifunctional platforms capable of improving efficacy and safety in cancer treatment, including in chemotherapy, immunotherapy, photothermal therapy, magnetic hyperthermia, photodynamic therapy, chemodynamic therapy, radiotherapy, molecularly targeted therapy, and after tumor surgical removal, and in general, chronic diabetic or tumor-induced wound healing, as well as in bone tissue engineering and myocardial tissue engineering. This review provides a thorough summary and critical insight of current advances on injectable nanocomposite hydrogels as an innovative approach that could bring substantial contributions to biomedical research and clinical practice, with a focus on their applications in cancer therapy, wound healing management, and tissue engineering.

Unveiling the Future: Opportunities in Long-Acting Injectable Drug Development for Veterinary Care

Long-acting injectable (LAI) formulations have revolutionized veterinary pharmaceuticals by improving patient compliance, minimizing dosage frequency, and improving therapeutic efficacy. These formulations utilize advanced drug delivery technologies, including microspheres, liposomes, oil solutions/suspensions, in situ-forming gels, and implants to achieve extended drug release. Biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA), and polycaprolactone (PCL) have been approved by the USFDA and are widely employed in the development of various LAIs, offering controlled drug release and minimizing the side effects. Various classes of veterinary medicines, including non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, and reproductive hormones, have been successfully formulated as LAIs. Some remarkable LAI products, such as ProHeart® (moxidectin), Excede® (ceftiofur), and POSILACTM (recombinant bovine somatotropin), show clinical relevance and commercial success. This review provides comprehensive information on the formulation strategies currently being used and the emerging technologies in LAIs for veterinary purposes. Additionally, challenges in characterization, in vitro testing, in vitro in vivo correlation (IVIVC), and safety concerns regarding biocompatibility are discussed, along with the prospects for next-generation LAIs. Continued advancement in the field of LAI in veterinary medicine is essential for improving animal health.

Advanced multifunctional coatings in ureteral stents: Interfacial design, properties, and applications

Ureteral stents play an essential role in the clinical practice of managing both benign and malignant urinary tract disorders. However, their use is accompanied by various complications, including tissue damage, urinary tract infection, biofilm formation, and encrustation. Although ureteral stents demonstrate remarkable efficacy in alleviating urinary tract obstruction, the multifaceted complications stemming from the demanding physiological environment of the urinary system continue to present a formidable challenge to clinical management. Therefore, the strategies to develop multifunctional stents are critical to address the complex microenvironment of long-term indwelling urinary tract. This review initially examines the challenges associated with the urinary tract interface environment and outlines strategies to overcome them. It then highlights the state-of-the-art advances in multifunctional urinary stents and discusses customized solutions that meet clinical practice depending on the duration of stent indwelling. Finally, we discuss the potential for designing smart-responsive multifunctional coating technologies, designed for precision therapy. This review provides insight into the development of advanced ureteral stents.

Development of a bioactive hyaluronic acid hydrogel functionalised with antimicrobial peptides for the treatment of chronic wounds

Chronic wounds present significant clinical challenges due to delayed healing and high infection risk. This study presents the development and characterisation of acrylated hyaluronic acid (AcHyA) hydrogels functionalised with gelatin (G) and the antimicrobial peptide (AMP) PP4-3.1 to enhance cellular responses while providing antimicrobial activity. AcHyA-G and AcHyA-AMP hydrogels were formed via thiol-acrylate crosslinking, enabling in situ AcHyA hydrogel formation with stable mechanical properties across varying gelatin concentrations. Biophysical characterisation of AcHyA-G hydrogels showed rapid gelation, elastic behaviour, uniform mesh size, and consistent molecular diffusion across all formulations. Moreover, the presence of gelatin enhanced stability without affecting the hydrogel's degradation kinetics. AcHyA-G hydrogels supported the adhesion and spreading of key cell types involved in wound repair (dermal fibroblasts and endothelial cells), with 0.5% gelatin identified as the optimal effective concentration. Furthermore, the conjugation of the AMP conferred bactericidal activity against Staphylococcus aureus and Escherichia coli, two of the most prevalent bacterial species found in chronically infected wounds. These results highlight the dual function of AcHyA-AMP hydrogels in promoting cellular responses and antimicrobial activity, offering a promising strategy for chronic wound treatment. Further in vivo studies are needed to evaluate their efficacy, including in diabetic foot ulcers.

Structural Color Contact Lenses from Cholesteric Cellulose Liquid Crystals

Colored contact lenses have gained popularity among young individuals owing to their ability to alter the appearance of the wearer's eyes. However, conventional lenses containing chemical dyes are susceptible to detachment of the pigment layer, which can lead to corneal damage. In this research, a novel cellulose-based structural color contact lens (SCCL) is presented that enhances aesthetic appeal via a cholesteric liquid crystal (CLC) layer. Methacrylate-functionalized hydroxypropyl cellulose (HPCMA) molecules self-assemble into CLC and are cross-linked within the lens mold, resulting in the colored iris region of the contact lens. By employing multistep polymerization techniques, lenses with composite colors and intricate shapes are fabricated. Moreover, by incorporating bioderived antimicrobial peptides into the structurally colored region of the lens, SCCLs are achieved with good biocompatibility, controlled drug release, and broad-spectrum antibacterial activity. The results of in vivo experiments using an animal model indicate that the SCCLs perform well in the treatment of bacterial keratitis. It is believed that these drug-loaded structurally colored contact lenses will lead to various advancements in ocular medical devices and provide antibacterial protection against infectious keratitis in the future.

Hydrogel-based dressing for wound healing: A systematic review of clinical trials

BACKGROUND

Chronic wounds pose significant healthcare challenges. Hydrogel-based wound dressings have garnered significant attention in the field of wound care. Furthermore, no severe adverse effect was reported for treatment with hydrogel in wound healing. However, a comprehensive review of their clinical application for enhancing chronic wound healing is lacking.

OBJECTIVES

This systematic review evaluates their clinical effectiveness of hydrogel-based dressing in managing chronic wounds and assesses the evidence supporting their use.

SEARCH METHODS

We searched the following databases PubMed, the Cochrane Library; Web of Science; and ClinicalTrials.gov. from January 2010 to January 2023.

SELECTION CRITERIA

Published clinical trial studies that evaluate the effect of hydrogel-based dressing on chronic wounds.

RESULT

We included 39 studies with 1786 participants (1818 wounds), 1024 of whom (1100 wounds) received hydrogel dressings while 679 patients (725 wounds) used non-hydrogel dressings. This systematic review of clinical research indicates that utilizing hydrogel dressings could potentially reduce the required time (31.17 ± 21.74 days) for wound healing and enhance the percentage of wound closure (63.76 ± 28.97 %).

CONCLUSIONS

This systematic review revealed that hydrogel dressings are effective in treatment of chronic wounds. Nonetheless, there is a necessity for additional long-term trials tailored to specific wound types and patient characteristics.

Regulating Intratumoral Fungi With Hydrogels: A Novel Approach to Modulating the Tumor Microbiome for Cancer Therapy

BACKGROUND

Fungi in tumors act as a double-edged sword, potentially worsening or alleviating malignancy based on the ecological balance within the tumor microenvironment (TME). Hydrogels, as innovative drug delivery systems, are poised to redefine treatment paradigms. As advanced biomaterials, they offer a versatile platform for encapsulating and releasing antifungal agents and immunomodulators, responding to the TME's unique demands.

METHODS

We have conducted and collated numerous relevant reviews and studies in recent years from three aspects: Hydrogels, intra-tumoral fungi, and tumor microbe microenvironment, in the hope of identifying the connections between hydrogels and intra-tumoral microbes.

RESULTS

This review underscores the crucial role of intra-tumoral microbes, particularly fungi, in tumorigenesis, progression, and treatment efficacy. At the same time, we concentrated on the findings of hydrogels investigations, with their remarkable adaptability to the tumor microenvironment emerge as intelligent drug delivery systems.

CONCLUSIONS

Hydrogels unique ability to precisely target and modulate the tumor microflora, including fungi, endows them with a significant edge in enhancing treatment efficacy. This innovative approach not only holds great promise for improving cancer therapy outcomes but also paves the way for developing novel strategies to control metastasis and prevent cancer recurrence.

Tailoring of agarose hydrogel to modulate its 3D bioprintability and mechanical properties for stem cell mediated bone tissue engineering

The intense gelling characteristics and viscosity constraints of agarose limit its utility as a sole ink material in 3D printing. This study presents the development of agarose bioink designed for cell-laden printing, featuring controlled printability, exceptional stiffness, and cell-responsiveness achieved via the insertion of photochemically reactive methacrylate groups. This chemical modification transforms the dense agarose network into a thinner structure, effecting a gentle thermogelling property that enhances the printability and facile cell encapsulation. Herein we examine the interplay between the degree of substitution and concentration variations to determine the optimal hydrogel composition. The best bioink composition possessed a lower shear modulus (storage modulus G' = 11.6 Pa) at 37 °C, assuring better bioprintability, while it possessed a Young's modulus of 1.4 ± 0.10 MPa in the crosslinked state, which is the highest reported in the natural single-matrix hydrogel systems. Studies with mesenchymal stem cells (MSC) confirmed that it is a good cell encapsulation matrix, achieving 111 % cell viability at 72 h. The bioprinted constructs promoted the osteogenic differentiation of MSC, as evidenced by mineralization and secretion of bone-related matrix. The gene expression analysis indicated that osteogenic marker expressions exhibited at least a two-fold increase on day 14 relative to the control group.

From waste to wonder: Biomass-derived nanocellulose and lignin-based nanomaterials in biomedical applications

Cellulose and lignin, as the most abundant biomass resources in nature, have been widely utilized in conventional industry. While their high-value potential remained underexplored for decades, recent advancements in nanotechnology and processing techniques have revealed their unique physicochemical properties, biocompatibility, and optical characteristics at the nanoscale, sparking significant interest in biomedical applications. Nanocellulose (NC), characterized by its high surface area, superior mechanical strength, and excellent biocompatibility, holds great promise in drug delivery, wound dressing, and tissue engineering. Similarly, lignin nanoparticles (LNPs) and lignin-based carbon quantum dots (L-CQDs), known for their multi-functionality, low toxicity, and outstanding fluorescence properties, emerge as sustainable alternatives for bio-imaging and bioanalytical detection. This review provides an overview of the hierarchical structure of biomass resources, details the preparation methods of cellulose- and lignin-based nanomaterials, and highlights their advancements in biomedical applications. Furthermore, it addresses the challenges and limitations associated with the clinical applications of these nanomaterials, offering insights and guidance for future research and development.

Ni(II)-Directed Supramolecular Metallogel: Stimuli Responsiveness and Semiconducting Device Fabrication

Metal-organic gels (MOGs) are a type of supramolecular complex that have become highly intriguing due to their synergistic combination of inorganic and organic elements. We report the synthesis and characterization of a Ni-directed supramolecular gel using chiral amino acid L-DOPA (3,4-dihydroxy phenylalanine) containing ligand, which coordinates with Ni(II) to form metal-organic gels with exceptional properties. The functional Ni(II)-gel was synthesized by heating nickel(II) acetate hexahydrate and the L-DOPA containing ligand in DMSO at 70 °C. The rheological tests have verified the gel with its mechanical stability, while a SEM image has shown a spherical aggregate morphology. The gel is photo-responsive in nature and exhibits gel to sol transformation upon adsorption of toxic gases like NH3 or H2S. Notably, electrical conductivity of the gel was observed in electronic metal-semiconductor (MS) junctions' devices with a measured conductivity of 0.9×10-6 Sm-1. These devices also exhibited Schottky barrier diode characteristics, underscoring the multifunctional potential of the Ni(II)-gel.

Biocompatible glycolipid derived from bhilawanol as an antibiofilm agent and a promising platform for drug delivery

Stimuli-responsive smart materials for biomedical applications have gained significant attention because of their potential for selectivity and sensitivity in biological systems. Even though ample stimuli-responsive materials are available, the use of traditional Ayurvedic compounds in the fabrication of pharmaceuticals is limited. Among various materials, gels are one of the essential classes because of their molecular-level tunability with little effort from the environment. In this study, we report a simple synthesis method for multifunctional glycolipids using a starting material derived from biologically significant natural molecules and carbohydrates in good yields. The synthesized glycolipids were prone to form a hydrogel by creating a 3D fibrous architecture. The mechanism of bottom-up assembly involving the molecular-level interaction was studied in detail using SEM, XRD, FTIR, and NMR spectroscopy. The stability, processability, and thixotropic behavior of the hydrogel were investigated through rheological measurements, and it was identified to be more suitable for biomedical applications. To evaluate the potential application of the self-assembled hydrogel in the field of medicine, we encapsulated a natural drug, curcumin, into a gel and studied its pH as a stimuli-responsive release profile. Interestingly, the encapsulated drug was released both in acidic and basic pH levels at a different rate, as identified using UV-vis spectroscopy. It is worth mentioning that the gelator used for fabricating smart soft materials displays significant potential in selectively compacting the biofilm formed by Streptococcus pneumoniae. We believe that the reported multifunctional hydrogel derived from bhilawanol-based glycolipid holds great promise in medicine.

Surfactant-rescued gelation: Stabilizing P123-chitosan hydrogels in blood-isotonic aqueous solutions for controlled drug delivery

The loss of gelation in Chitosan-Pluronic composite hydrogels under physiological saline conditions restricts their potential for drug delivery applications. To this effect, we present a dynamic and composite hydrogel system based on Pluronic P123 and chitosan, which restores gelation upon the addition of sodium dodecyl sulfate (SDS), even in the presence of NaCl at blood-isotonic concentrations. The entry of SDS induces electrostatic interactions and hydrophobic associations, enabling robust gel formation under physiological conditions. The gelation behavior can be desirably modified by varying chitosan concentration and temperature, allowing tunable mechanical properties suitable for drug delivery applications. Rheological analysis confirmed enhanced mechanical stability in saline environments, while FTIR spectroscopy elucidated molecular interactions within the hydrogel. Quinine sulfate release studies showed sustained drug release without burst effects. Kinetic modeling indicated a predominantly non-Fickian transport mechanism, governed by both diffusion and polymer relaxation. This surfactant-rescued gelation strategy stabilizes chitosan-based hydrogels in physiological conditions, making them promising candidates for controlled drug delivery.

Surface-Vinylated Cellulose Nanocrystals as Cross-Linkers for Hydrogel Composites

Cellulose nanocrystal (CNC) fillers have been shown to significantly improve the performance of polymer composites and hydrogels, elevating both strength and toughness. Polymer grafting from the surface of the nanocrystals has been employed to enhance matrix-filler interactions and keep the fillers dispersed within the matrix. However, such approaches often rely on multistep syntheses and diligent process control. Here, we propose modifying the nanocrystal surface to carry vinyl moieties, turning the particles into cross-linking comonomers. Using allyl glycidyl ether in an aqueous modification route, we were able to decorate the CNCs with varying amounts of vinyl moieties. Subsequent dispersion in 2-hydroxy methacrylate and thermally initiated free radical polymerization yielded composite materials that showed superior mechanical performance compared to those obtained from monomeric cross-linkers and unmodified CNCs. The large discrepancies in the observed glass transition temperatures of the obtained materials suggest, however, that the impact of the fillers on the polymerization kinetics is significant and less easily explained.

Potential of vB_Pa_ZCPS1 phage embedded in situ gelling formulations as an ocular delivery system to attenuate Pseudomonas aeruginosa keratitis in a rabbit model

Pseudomonas aeruginosa keratitis (or pink eye) is a challenging ocular infection that causes serious complications due to the deficiency of effective antibiotic treatment. Thus, in this study we isolated and characterized a specific bacteriophage, phage vB_Pa_ZCPS1, to be used to formulate an in situ- gel loaded bacteriophage for an in vivo rabbit infection treatment model. Phage vB_Pa_ZCPS1 is a double-stranded DNA bacterial virus, of 46,135 bp encoding 75 open reading frames (ORFs) with no antibiotic resistance genes detected. Moreover, it has a podoviral morphotype from the Caudoviricetes class with a 62.4 nm capsid and a short inflexible tail of around 18.8 nm, as indicated by the transmission electron microscope (TEM). Phage vB_Pa_ZCPS1 presented good stability to the UV exposure and a wide range of pH values from 3.0 to 11.0. In addition, the phage-bacteria dynamics study showed that phage vB_Pa_ZCPS1 was effective against P. aeruginosa, especially at low multiplicities of infections (MOIs), including 0.001, 0.01, and 0.1. Respectively, it was loaded to the characterized in situ gel composed of 14 % Pluronic F-127 and 1.5 % HPMC K4M polymer. The in situ-gel has a gelling time of 30 s ± 1, and a temperature of 33 °C ± 1, where the viscosity of the gel increases 10-fold. For the in vivo trial, the infected group treated with phage presented improved clinical outcomes, where the histopathological analysis revealed normal corneal thickness and intact corneal stratified squamous epithelium. Thus, the in situ-gel loaded phage vB_Pa_ZCPS1 could be a potential candidate approach to treat P. aeruginosa keratitis.

Hydrogel Performance in Boosting Plant Resilience to Water Stress-A Review

Hydrogels have emerged as a transformative technology in agriculture, offering significant potential to enhance crop resilience, improve water use efficiency, and promote sustainable farming practices. These three-dimensional polymeric networks can absorb and retain water, making them particularly valuable in regions facing water scarcity and unpredictable rainfall patterns. This review examines the types, properties, and applications of hydrogels in agriculture, highlighting their role in improving soil moisture retention, enhancing nutrient delivery by, and increasing crop yield. The discussion extends to the economic and environmental implications of hydrogel use, including their potential to reduce irrigation costs by and minimize soil erosion. The review also explores the latest innovations in hydrogel technology, such as smart hydrogels and biodegradable alternatives, which offer new possibilities for precision agriculture and environmental sustainability. Despite promising benefits, challenges such as the higher cost of synthetic hydrogels, environmental impact, and performance variability across different soil types remain. Addressing these challenges requires a multidisciplinary approach that integrates advancements in material science, agronomy, and environmental policy. The future outlook for hydrogels in agriculture is optimistic, with ongoing research poised to refine their applications and expand their use across diverse agricultural systems. By leveraging the capabilities of hydrogels, agriculture can achieve increase in productivity, ensure food security, and move towards a more sustainable and resilient agricultural landscape.

Degradation, swelling, and drug release behavior of injectable ETTMP/PEGDA hydrogels

The erosion and drug release behavior of an injectable hydrogel composed of ethoxylated trimethylolpropane tri-3-mercaptopropionate (ETTMP) and poly(ethylene glycol) diacrylate were determined under physiological conditions. Water and polymer mass changes were monitored over time to characterize the swelling/deswelling and erosion of the hydrogel tablets. Experimental data were collected for hydrogels with varying polymer fractions. These data were used to develop an empirical model to predict the eroding mass change and equilibrium water content across different compositions. Three easily detectable model drugs (methylene blue (MB), sulforhodamine 101, and chloroquine) were loaded into 25, 35, and 50 wt% polymer hydrogels to understand their drug release behavior. The gelation time and time for total drug release were dependent on the weight fraction of the polymer in the hydrogel and varied with the pH of the drug solutions, with more acidic drugs increasing gelation time. Complete drug release was not observed for MB because of the reaction with ETTMP thiol groups, demonstrating the importance of understanding the potential interactions between the drug and polymer. Drug-loaded hydrogels were also monitored for erosion and were found to swell more than their neat counterparts for all drugs tested, suggesting an effect of drug loading on the extent of hydrogel crosslinking.

The angle of polarized light (AOP) property for optical classification of the crosslinked polymer

Light-matter interaction has been profoundly studied for sample material classification. However, the optical classification of the sample through the polarized light-matter interaction remains underexplored. It is limited to the measurement of intensity instead of the angle of polarized light (AOP) for its degree of polarization. Measurement of the degree of polarization within a material or a medium becomes easier with a simple, low-cost and direct measurement without the need of any probing or labelling agent. Thus, this investigation was conducted mainly to determine the angle of polarized light (AOP) property of the crosslinked polymer using our proposed polarization measurement technique as an alternative approach of the material classification. The angle of polarized light (AOP) of each polymer was determined in combination property of polarization by absorption, transmission, and scattering. Our proposed scattered angle (ס=90°, 100°, 110°, and 120°) successfully measured the AOP of each polymer that can be classified into two groups. Group 1 represents the AOP value ( [Formula: see text] ) for a test sample of t1 = 3.1 %, 3.2, and 3.3 % with comparison to the normal sample (n = 3.0 %) and Group 2 represents the AOP value ( [Formula: see text] ) for the test sample oft2 = 3.4 %, 3.6 % and 3.7 % with comparison to the normal sample (n = 3.0 %). Our study proved a direct, easy, and simple method of determining the degree of polarization of the polymers without the need of complex formulation and labelling protocol. Therefore, this work may enhance the investigation of the optical properties of the agarose-based tissue-mimicking phantom (AGTMP) for modeling or simulation of the real biological sample in the future. Our polarization measures are worthy of further explored and implemented in current optical imaging techniques or sensing platform for optical classification of the biomaterials.

Development of Bioorthogonally Degradable Tough Hydrogels Using Enamine N-Oxide Based Crosslinkers

Inducibly degradable polymers present new opportunities to integrate tough hydrogels into a wide range of biomaterials. Rapid and inducible degradation enables fast transition in material properties without sacrificing material integrity prior to removal. In pursuit of bioorthogonal chemical modalities that will enable inducible polymer degradation in biologically relevant environments, enamine N-oxide crosslinkers are developed for double network acrylamide-based polymer/alginate hydrogels. Bioorthogonal dissociation initiated by the application of aqueous diboron solution through several delivery mechanisms effectively lead to polymer degradation. Their degradation by aqueous B2(OH)4 solution results in a fracture energy half-life of <10 min. The biocompatibility of the degradable hydrogels and B2(OH)4 reagent is assessed, and the removability of strongly adhered tough hydrogels on mice skin is evaluated. Thermoresponsive PNiPAAm/Alg hydrogels are fabricated and application of the hydrogels as a chemically inducible degradable intraoral wound dressing is demonstrated. It is demonstrated through in vivo maximum tolerated dose studies that diboron solution administered to mice by oral gavage is well tolerated. Successful integration of enamine N-oxides within the tough double network hydrogels as chemically degradable motifs demonstrates the applicability of enamine N-oxides in the realm of polymer chemistry and highlights the importance of chemically induced bioorthogonal dissociation reactions for materials science.

A novel avenue in the successful synthesis of Schiff base macromolecules via innovative plasma and classical approaches

Schiff base macromolecules have been successfully synthesized, utilizing a classical chemistry route and a dielectric barrier discharge (DBD) plasma technique. The synthesis of monomeric units has been accomplished through typical reactions of aldehyde and amine functional molecules. The condensation polymerization of the Schiff base molecules has been instigated chemically, using p-toluene sulfonyl chloride in refluxed ethanol. The molecular weight of the obtained polymers was discovered to be 524, 664 and 1,503,228 for Schiff base polymers 4a and 4b, respectively. Additionally, the polymerization reactions were prompted, employing a Dielectric Barrier Discharge (DBD) atmospheric pressure air plasma technique. The DBD plasma demonstrated a very powerful routine to produce high molecular weights macromolecules with optimum condition at 5 min. duration time, which could be an ecofriendly strategy to acquire this class of materials. The new polymeric materials have been characterized utilizing FTIR and NMR spectroscopy. Moreover, the complexation of polymer 4b with various metal moieties, Ru (II), Co (II), Cu (II), and Ni (II), has been executed in order to have a comparative study of their antitumor activity against MCF-7, HCT-116, and HepG-2 cell lines. Furthermore, the density functional theory was exploited to optimize the polymers and their complexes, and their HOMO-LUMO and energy gap were calculated, which was utilized to examine the inter/intra molecular charge transfer. The molecular electrostatic potential map was similarly quantified to investigate the reactive sites that are present in the investigated molecules. The result for the docking study confirmed that these complexed polymers adopted numerous important interactions with the amino acid of the targeted enzyme.

Recent Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Engineering Strategies for Precise Strike Therapy against Tumor

Effective drug delivery relies on the selection of suitable carriers, which is crucial for protein-based therapeutics such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). One of the key advantages of TRAIL is its ability to selectively induce apoptosis in cancer cells excluding healthy tissues by binding to death receptors DR4 and DR5, which are highly expressed in various cancer cells. Despite this promise, the clinical application of TRAIL has been limited by its short half-life, limited stability, and inefficient delivery to tumor sites. To overcome currently available clinical and engineering approaches, a series of sophisticated strategies is required: (a) the design of biomaterial-mediated carriers for enhanced targeting efficacy, particularly via optimizing selected materials, composition, formulation, and surface modulation. Moreover, (b) development of genetically modified cellular products for augmented TRAIL secretion toward tumor microenvironments and (c) cell surface engineering techniques for TRAIL immobilization onto infusible cell populations are also discussed in the present review. Among these approaches, living cell-based carriers offer the distinct advantage of systemically administered TRAIL-functionalized cells capturing circulating tumor cells in the bloodstream, thereby preventing secondary tumor formation. This review provides insight into the development of novel TRAIL delivery platforms, discusses considerations for clinical translation, and suggests future directions and complementary strategies to advance the field of TRAIL-based cancer therapeutics.

Hydrogel Delivery Systems for Biological Active Substances: Properties and the Role of HPMC as a Carrier

Hydrogel delivery systems are popular dosage forms that have a number of advantages, such as ease of use, painlessness, increased efficiency due to prolongation of rheological, swelling and sorption characteristics, regulation of drug release, and stimulus sensitivity. Particular interest is shown in hydrogels of cellulose ether derivatives due to the possibility of obtaining their modified forms to vary the solubility, the degree of prolonged action, and the release of the active substance, as well as their widespread availability, affordability, and the possibility of sourcing raw materials from different sources. Hydroxypropyl methylcellulose (HPMC, "hypromellose") is one of the most popular cellulose ethers in the production of medicines as a filler, coating and carrier. Research on hydrogel carriers based on polymer complexes and modified forms of HPMC using acrylic, citric, and lactic acids, PVP, chitosan, Na-CMC, and gelatin is of particular interest, as they provide the necessary rheological and swelling characteristics. There is growing interest in medical transdermal hydrogels, films, capsules, membranes, nanocrystals, and nanofibers based on HPMC with the incorporation of biologically active substances (BASs), especially those of plant origin, as antibacterial, wound-healing, antimicrobial, mucoadhesive, anti-inflammatory, and antioxidant agents. The aim of this article is to review modern research and achievements in the field of hydrogel systems based on cellulose ethers, particularly HPMC, analyzing their properties, methods of production, and prospects for application in medicine and pharmacy.

Biomimetic Elastomer-Clay Nanocomposite Hydrogels with Control of Biological Chemicals for Soft Tissue Engineering and Wound Healing

Resilient hydrogels are of great interest in soft tissue applications, such as soft tissue engineering and wound healing, with their biomimetic mechanical and hydration properties. A critical aspect in designing hydrogels for healthcare is their functionalities to control the surrounding biological environments to optimize the healing process. Herein, we have created an elastomer-clay nanocomposite hydrogel system with biomimetic mechanical behavior and sustained drug delivery of bioactive components and malodorous diamine-controlling properties. These hydrogels were prepared by a combined approach of melt intercalation of poly(ethylene glycol) and montmorillonite clay, followed by in situ cross-linking with a branched poly(glycerol sebacate) prepolymer. The hydration, vapor transmission, and surface wettability of the hydrogels were readily controlled by varying the clay content. Their mechanical properties were also modulated to mimic the Young's moduli (ranging between 12.6 and 105.2 kPa), as well as good flexibility and stretchability of soft tissues. A porous scaffold with interconnected pore structures as well as full and instant shape recovery was fabricated from a selected nanocomposite to demonstrate its potential applications as soft tissue scaffolds and wound healing materials. Biodegradability and biocompatibility were tested in vitro, showing controllable degradation kinetics with clay and no evidence of cytotoxicity. With the high surface area and absorption capacity of the clay, sustained drug delivery of a proangiogenic agent of 17β-estradiol as a model drug and the ability to control the malodorous diamines were both achieved. This elastomer-clay nanocomposite hydrogel system with a three-dimensional interconnected porous scaffold architecture and controllable hydration, mechanical, and biodegradable properties, as well as good biocompatibility and the ability to control the biological chemical species of the surrounding environments, has great potential in soft tissue engineering and wound healing.

Multicompartmental Hydrogel Microspheres with a Concentric Thin Oil Layer: Protecting and Targeting Therapeutic Agents for Inflammatory Bowel Disease

Although oral delivery of therapeutic agents offers numerous benefits, its application is limited due to the digestive tract's harsh conditions (e.g., strong acidity and high osmolarity), which impair activity and create challenges in achieving targeted release into the intestine. Here, we present multicompartmental hydrogel microspheres equipped with a concentric oil layer to significantly enhance the oral drug delivery efficiency for treating inflammatory bowel disease (IBD). These microspheres are created through the utilization of triple-emulsion droplets, featuring intermediate oil layers that distinctively separate two prepolymer phases, allowing us to fine-tune the composition of each compartment through a tailored polymerization strategy. We demonstrate that the oil layer can protect the encapsulated material by preventing exposure to the acidic environment of the stomach during the digestive process. Unlike aqueous core capsules, the core is composed of hydrogel, which provides high stability even under high osmolarity conditions in the stomach. By fine-tuning the shell's composition, we can develop capsules that release selectively in response to the gut's pH conditions. We demonstrate the system's efficacy by preserving the anti-inflammatory activities of 5-aminosalicylic acid (5-ASA) and Lys-Pro-Val (KPV) under stomach conditions and maintaining their therapeutic effects on colonic epithelial cell migration and proliferation.

Smart Poly(N-isopropylacrylamide)-Based Hydrogels: A Tour D'horizon of Biomedical Applications

Hydrogels are innovative materials characterized by a water-swollen, crosslinked polymeric network capable of retaining substantial amounts of water while maintaining structural integrity. Their unique ability to swell or contract in response to environmental stimuli makes them integral to biomedical applications, including drug delivery, tissue engineering, and wound healing. Among these, "smart" hydrogels, sensitive to stimuli such as pH, temperature, and light, showcase reversible transitions between liquid and semi-solid states. Thermoresponsive hydrogels, exemplified by poly(N-isopropylacrylamide) (PNIPAM), are particularly notable for their sensitivity to temperature changes, transitioning near their lower critical solution temperature (LCST) of approximately 32 °C in water. Structurally, PNIPAM-based hydrogels (PNIPAM-HYDs) are chemically versatile, allowing for modifications that enhance biocompatibility and functional adaptability. These properties enable their application in diverse therapeutic areas such as cancer therapy, phototherapy, wound healing, and tissue engineering. In this review, the unique properties and behavior of smart PNIPAM are explored, with an emphasis on diverse synthesis methods and a brief note on biocompatibility. Furthermore, the structural and functional modifications of PNIPAM-HYDs are detailed, along with their biomedical applications in cancer therapy, phototherapy, wound healing, tissue engineering, skin conditions, ocular diseases, etc. Various delivery routes and patents highlighting therapeutic advancements are also examined. Finally, the future prospects of PNIPAM-HYDs remain promising, with ongoing research focused on enhancing their stability, responsiveness, and clinical applicability. Their continued development is expected to revolutionize biomedical technologies, paving the way for more efficient and targeted therapeutic solutions.

Ion-Specific Gelation and Internal Dynamics of Nanocellulose Biocompatible Hybrid Hydrogels: Insights from Fluctuation Analysis

Hydrogels find widespread use in bioapplications for their ability to retain large amounts of water while maintaining structural integrity. In this article, we investigate hybrid hydrogels made of nanocellulose and either amino-polyethylenglycol or sodium alginates and we present two novel results: (1) the biocompatibility of the amino-containing hybrid gel synthesized using a simplified receipt does not require any intermediate synthetic step to functionalize either component and (2) the fluctuation in the second-order correlation function of a dynamic light scattering experiment provides relevant information about the characteristic internal dynamics of the materials across the entire sol-gel transition as well as quantitative information about the ion-specific gel formation. This novel approach offers significantly better temporal (tens of μs) and spatial (tens of μm) resolution than many other state-of-the-art techniques commonly used for such analyses (such as rheometry, SAXS, and NMR) and it might find widespread application in the characterization of nano- to microscale dynamics in soft materials.

Medical Benefits and Polymer Applications of Grapes

Grapes are a fruit with origins dating back to ancient times. Their first recorded use, as mentioned in the Bible, was in winemaking. The abundance of bioactive compounds in grapes makes them highly valuable. So far, many varieties of cultivated grapes have been developed for table grapes, wine grapes, and raisin production. In addition to these uses, since grapes contain a variety of nutrients, including resveratrol, flavonoids (such as flavonols, anthocyanins, and catechins), melatonin, vitamins, acids, tannins, and other antioxidants, grape extracts have been widely studied for medical applications. This paper reviews the medical effects of these compounds on cancer, cardiovascular disease, brain and neurological disorders, eye diseases, skin disorders, kidney health, diabetes, and gastric diseases, along with the medical applications of grapes in drug delivery, wound dressing, and tissue engineering. In addition, the limitations of the grapes-derived polymers and future research perspectives are discussed. These benefits highlight that the value of grapes extends far beyond their traditional use in wine and raisin production.

Hydrogels and Microgels: Driving Revolutionary Innovations in Targeted Drug Delivery, Strengthening Infection Management, and Advancing Tissue Repair and Regeneration

Hydrogels and microgels are emerging as pivotal platforms in biomedicine, with significant potential in targeted drug delivery, enhanced infection management, and tissue repair and regeneration. These gels, characterized by their high water content, unique structures, and adaptable mechanical properties, interact seamlessly with biological systems, making them invaluable for controlled and targeted drug release. In the realm of infection management, hydrogels and microgels can incorporate antimicrobial agents, offering robust defenses against bacterial infections. This capability is increasingly important in the fight against antibiotic resistance, providing innovative solutions for infection prevention in wound dressings, surgical implants, and medical devices. Additionally, the biocompatibility and customizable mechanical properties of these gels make them ideal scaffolds for tissue engineering, supporting the growth and repair of damaged tissues. Despite their promising applications, challenges such as ensuring long-term stability, enhancing therapeutic agent loading capacities, and scaling production must be addressed for widespread adoption. This review explores the current advancements, opportunities, and limitations of hydrogels and microgels, highlighting research and technological directions poised to revolutionize treatment strategies through personalized and regenerative approaches.

Different exosomes are loaded in hydrogels for the application in the field of tissue repair

Exosomes are double-membrane vesicular nanoparticles in the category of extracellular vesicles, ranging in size from 30 to 150 nm, and are released from cells through a specific multi-step exocytosis process. Exosomes have emerged as promising tools for tissue repair due to their ability to transfer bioactive molecules that promote cell proliferation, differentiation, and tissue regeneration. However, the therapeutic application of exosomes is hindered by their rapid clearance from the body and limited retention at the injury site. To overcome these challenges, hydrogels, known for their high biocompatibility and porous structure, have been explored as carriers for exosomes. Hydrogels can provide a controlled release mechanism, prolonging the retention time of exosomes at targeted tissues, thus enhancing their therapeutic efficacy. This review focuses on the combination of different exosomes with hydrogels in the context of tissue repair. We first introduce the sources and functions of exosomes, particularly those from mesenchymal stem cells, and their roles in regenerative medicine. We then examine various types of hydrogels, highlighting their ability to load and release exosomes. Several strategies for encapsulating exosomes in hydrogels are discussed, including the impact of hydrogel composition and structure on exosome delivery efficiency. Finally, we review the applications of exosomes-loaded hydrogels in the repair of different tissues, such as skin, bone, cartilage, and nerve, and explore the challenges and future directions in this field. The combination of exosomes with hydrogels offers significant promise for advancing tissue repair strategies and regenerative therapies.

Construction of carbon dot-embedded fluorescent hydrogels based on oxidized gum arabic-gelatin Schiff base for Cr(VI) detection applications

In this study, a novel nitrogen-doped carbon quantum dot/oxidized gum arabic-gelatin-based fluorescent probe (NAH) was prepared using gelatin (GL) and gum arabic (AG) biomolecules. The primary network structure of this hydrogel consisted of polyacrylamide (PAM), while a secondary network structure was constructed between oxidized gum arabic and gelatin through the reaction of the Schiff base, which significantly enhanced the mechanical properties, the stress and strain of NAH reached 266.47 KPa and 2175.75 %. Nitrogen-doped carbon dots (NCDs) with yellow fluorescence emission properties were synthesized by hydrothermal method using salicylic acid as the carbon source and o-phenylenediamine as the nitrogen source. The fluorescent sensor obtained by compounding NCDs with hydrogel was able to selectively detect Cr(VI). The linear range of its detection was 0-90 μM, and the detection limit was 0.19 μM. The maximum theoretical adsorption capacity of the NAH hydrogel was 169.4 mg/g, and its adsorption isotherm conformed to the Langmuir adsorption isotherm model, and the adsorption kinetics conformed to the quasi-secondary kinetic model. Compared with the NCDs solution, the NAH hydrogel showed superior comprehensive performance, especially in solving the problem of recovery of NCDs. Meanwhile, this hydrogel provides an effective insight into the efficient detection and adsorption of environmental pollutants.

Hydrogels and Nanogels: Pioneering the Future of Advanced Drug Delivery Systems

Conventional drug delivery approaches, including tablets and capsules, often suffer from reduced therapeutic effectiveness, largely attributed to inadequate bioavailability and difficulties in ensuring patient adherence. These challenges have driven the development of advanced drug delivery systems (DDS), with hydrogels and especially nanogels emerging as promising materials to overcome these limitations. Hydrogels, with their biocompatibility, high water content, and stimuli-responsive properties, provide controlled and targeted drug release. This review explores the evolution, properties, and classifications of hydrogels versus nanogels and their applications in drug delivery, detailing synthesis methods, including chemical crosslinking, physical self-assembly, and advanced techniques such as microfluidics and 3D printing. It also examines drug-loading mechanisms (e.g., physical encapsulation and electrostatic interactions) and release strategies (e.g., diffusion, stimuli-responsive, and enzyme-triggered). These gels demonstrate significant advantages in addressing the limitations of traditional DDS, offering improved drug stability, sustained release, and high specificity. Their adaptability extends to various routes of administration, including topical, oral, and injectable forms, while emerging nanogels further enhance therapeutic targeting through nanoscale precision and stimuli responsiveness. Although hydrogels and nanogels have transformative potential in personalized medicine, challenges remain in scalable manufacturing, regulatory approval, and targeted delivery. Future strategies include integrating biosensors for real-time monitoring, developing dual-stimuli-responsive systems, and optimizing surface functionalization for specificity. These advancements aim to establish hydrogels and nanogels as cornerstones of next-generation therapeutic solutions, revolutionizing drug delivery, and paving the way for innovative, patient-centered treatments.

Evaluation effect of alginate hydrogel containing losartan on wound healing and gene expression

Skin tissue engineering has become an increasingly popular alternative to conventional treatments for skin injuries. Hydrogels, owing to their advantages have become the ideal option for wound dressing, and they are extensively employed in a mixture of different drugs to accelerate wound healing. Sodium alginate is a readily available natural polymer with advantages such as bio-compatibility and a non-toxicological nature that is commonly used in hydrogel form for medical applications such as wound repair and drug delivery in skin regenerative medicine. Losartan is a medicine called angiotensin receptor blocker (ARB) that can prevent fibrosis by inhibiting AT1R (angiotensin II type 1 receptor). In this research, for the first time, three-dimensional scaffolds based on cross-linked alginate hydrogel with CaCl2 containing different concentrations of losartan for slow drug release and exudate absorption were prepared and characterized as wound dressing. Alginate hydrogel was mixed with 10, 1, 0.1, and 0.01 mg/mL of losartan, and their properties such as morphology, chemical structure, water uptake properties, biodegradability, stability assay, rheology, blood compatibility, and cellular response were evaluated. In addition, the therapeutic efficiency of the developed hydrogels was then assessed in an in vitro wound healing model and with a gene expression. The results revealed that the hydrogel produced was very porous (porosity of 47.37 ± 3.76 µm) with interconnected pores and biodegradable (weight loss percentage of 60.93 ± 4.51% over 14 days). All hydrogel formulations have stability under various conditions. The use of CaCl2 as a cross-linker led to an increase in the viscosity of alginate hydrogels. An in vitro cell growth study revealed that no cytotoxicity was observed at the suggested dosage of the hydrogel. Increases in Losartan dosage, however, caused hemolysis. In vivo study in adult male rats with a full-thickness model showed greater than 80% improvement of the primary wound region after 2 weeks of treatment with alginate hydrogel containing 0.1 mg/mL Losartan. RT-PCR and immunohistochemistry analysis showed a decrease in expression level of TGF-β1 and VEGF in treatment groups. Histological analysis demonstrated that the alginate hydrogel containing Losartan can be effective in wound repair by decreasing the size of the scar and tissue remodeling, as evidenced by future in vivo studies.

The versatility of peptide hydrogels: From self-assembly to drug delivery applications

Pharmaceuticals often suffer from limitations such as low solubility, low stability, and  short half-life. To address these challenges and reduce the need for frequent drug administrations, a more efficient delivery is required. In this context, the development of controlled drug delivery systems, acting as a protective depot for the drug, has expanded significantly over the last decades. Among these, injectable hydrogels have emerged as a promising platform, especially in view of the rise of biologicals as therapeutics. Hydrogels are functional, solid-like biomaterials, composed of cross-linked hydrophilic polymers and high water content. Their physical properties, which closely mimic the extracellular matrix, make them suitable for various biomedical applications. This review discusses the different types of hydrogel systems and their self-assembly process, with an emphasis on peptide-based hydrogels. Due to their structural and functional diversity, biocompatibility, synthetic accessibility, and tunability, peptides are regarded as promising and versatile building blocks. A comprehensive overview of the variety of peptide hydrogels is outlined, with β-sheet forming sequences being highlighted. Key factors to consider when using peptide hydrogels as a controlled drug delivery system are reviewed, along with a discussion of the main drug release mechanisms and the emerging trend towards affinity-based systems to further refine drug release profiles.

A bibliometric analysis of hydrogel research in various fields: the trends and evolution of hydrogel application

Hydrogel, a polymer material with a three-dimensional structure, has considerably expanded in research across multiple fields lately. However, the lack of a comprehensive review integrating the research status of hydrogel across diverse fields has hindered the development of hydrogel. This bibliometric analysis reviewed the hydrogel-related research over the past decades, emphasizing the evolution, status, and future directions within a multitude of fields, such as materials science, chemistry, polymer science, engineering, physics, biochemistry molecular biology, pharmacology pharmacy, cell biology, biotechnology applied microbiology, etc. We encapsulated applications and the potential of hydrogel in wound healing, drug delivery, cell encapsulation, bioprinting, tissue engineering, electronic products, environment applications, and disease treatment. This study integrated the current matrix system and characteristics of hydrogels, aiming to offer a cross-field reference for hydrogel researchers and promote the advancement of hydrogel research. Furthermore, we proposed a novel and reproducible bibliometric research paradigm, which can provide a more comprehensive analysis of the trends and trajectory of a research field.

Improving the bioactivity and mechanical properties of poly(ethylene glycol)-based hydrogels through a supramolecular support network

Most synthetic hydrogels are formed through radical polymerization to yield a homogenous covalent meshwork. In contrast, natural hydrogels form through mechanisms involving both covalent assembly and supramolecular interactions. In this communication, we expand the capabilities of covalent poly(ethylene glycol) (PEG) networks through co-assembly of supramolecular peptide nanofibers. Using a peptide hydrogelator derived from the tryptophan zipper (Trpzip) motif, we demonstrate how in situ formation of nanofiber networks can tune the stiffness of PEG-based hydrogels, while also imparting shear thinning, stress relaxation, and self-healing properties. The hybrid networks show enhanced toughness and durability under tension, providing scope for use in load bearing applications. A small quantity of Trpzip peptide renders the non-adhesive PEG network adhesive, supporting adipose derived stromal cell adhesion, elongation, and growth. The integration of supramolecular networks into covalent meshworks expands the versatility of these materials, opening up new avenues for applications in biotechnology and medicine.

Development and application of hydrogels in pathogenic bacteria detection in foods

Hydrogels are 3D networks of water-swollen hydrophilic polymers. It possesses unique properties (e.g., carrying biorecognition elements and creating a micro-environment) that make it highly suitable for bacteria detection (e.g., expedited and effective bacteria detection) and mitigation of bacterial contamination in specific environments (e.g., food systems). This study first introduces the materials used to create hydrogels for bacteria detection and the mechanisms for detection. We also summarize different hydrogel-based detection methods that rely on external stimuli and biorecognition elements, such as enzymes, temperature, pH, antibodies, and oligonucleotides. Subsequently, a range of widely utilized bacterial detection technologies were discussed where recently hydrogels are being used. These modifications allow for precise, real-time diagnostics across varied food matrices, responding effectively to industry needs for sensitivity, scalability, and portability. After highlighting the utilization of hydrogels and their role in these detection techniques, we outline limitations and advancements in the methods for the detection of foodborne pathogenic bacteria, especially the potential application of hydrogels in the food industry.

Biocompatible autonomous self-healing PVA-CS/TA hydrogels based on hydrogen bonding and electrostatic interaction

The biocompatible autonomous self-healing hydrogels have great potential in biomedical applications. However, the fairly weak tensile strength of the hydrogels seriously hinders their application. Here, we introduced chitosan (CS) into the polyvinyl alcohol (PVA)-tannic acid (TA) hydrogel and investigated the effects of the CS content, as CS can not only form reversible H bonds with PVA and TA but also form reversible electrostatic interactions with TA. Since the bond energy of electrostatic interaction is much stronger than that of the H bond, the tensile strength and self-healing properties of PVA-TA hydrogel can potentially be improved by adding the CS. The results suggested that when the PVA content and the total content of CS and TA were fixed (PVA: 30 wt.%; CS + TA: 3 wt.%) and the CS content was increased to 1 wt.%, the tensile strength of the PVA-CS/TA hydrogel could be up to 447 kPa, and the self-healing efficiency remained at 84% in 2 h. Compared with the reported self-healing hydrogels with similar biocompatibility and self-healing properties, whose tensile strength is usually less than 300 kPa, the PVA-CS/TA hydrogel prepared here shows a significant improvement in the tensile strength.

Role of Ionizing Radiation Techniques in Polymeric Hydrogel Synthesis for Tissue Engineering Applications

Hydrogels are widely utilized in industrial and scientific applications owing to their ability to immobilize active molecules, cells, and nanoparticles. This capability has led to their growing use in various biomedical fields, including cell culture and transplantation, drug delivery, and tissue engineering. Among the available synthesis techniques, ionizing-radiation-induced fabrication stands out as an environmentally friendly method for hydrogel preparation. In alignment with the current requirements for cleaner technologies, developing hydrogels using gamma and electron beam irradiation technologies represents a promising and innovative approach for their biomedical applications. A key advantage of these methods is their ability to synthesize homogeneous three-dimensional networks in a single step, without the need for chemical initiators or catalysts. Additionally, the fabrication process is controllable by adjusting the radiation dose and dose rate.

Unlocking the Potential of Hybrid Nanocomposite Hydrogels: Design, Mechanical Properties and Biomedical Performances

Hybrid nanocomposite hydrogels consist of the homogeneous incorporation of nano‐objects in a hydrogel matrix. The latter, whether made of natural or synthetic materials, possesses a microporous, soft structure that makes it an ideal host for a variety of polymer and lipid‐based nano‐objects as well as metal‐ and silica‐based ones. By carefully choosing the composition and the proportions of the different constituents, hybrid hydrogels can display a wide array of properties, from simple enhancement of mechanical characteristics to specific bioactivity. This review aims to provide an overview of the state of the art in hybrid hydrogels highlighting key aspects that make them a promising choice for a variety of biomedical applications. Strategies for the preparation of hybrid hydrogels are discussed by covering the selection of individual components. The review will also explore the physico‐chemical and rheological characterization of these materials, which is essential for understanding their structure and function, ultimately satisfying specifications for the intended use. Successful examples of biomedical applications will also be presented, and the main challenges to be met will be discussed, with the aim of stimulating the research community to exploit the full potential of these materials.

Polymerization-Induced Self-Assembly Providing PEG-Gels with Dynamic Micelle-Crosslinked Hierarchical Structures and Overall Improvement of Their Comprehensive Performances

Polymer gels are fascinating soft materials and have become excellent candidates for wearable electronics, biomedicine, sensors, etc. Synthetic gels usually suffer from poor mechanical properties, and integrating good mechanical properties, adhesiveness, stability, and self-healing performances in one gel is more difficult. Herein, polymerization-induced self-assembly (PISA) providing PEG-gels with an overall improvement in their comprehensive performances is reported. PISA synthesis is carried out in PEG (solvent) to efficiently produce various nanoparticles, which are used as the nanofillers in the subsequent synthesis of PEG-gels with dynamic micelle-crosslinked hierarchical structures. Compared to hydrogels, PEG-gels show excellent long-term stability due to the nonvolatile feature of PEG solvent. The hierarchical PEG-gels (with nanofillers) exhibit better mechanical and adhesive properties than the homogeneous-gels (without nanofillers). The energy dissipation mechanism of the PEG-gels is analyzed via stress relaxation and cyclic mechanical tests. High-density hydrogen bonds between the micelles and PAA matrix can be broken and reformed, endowing better self-healing properties of the dynamic micelle-crosslinked PEG gels. This work provides a simple strategy for producing hierarchical structural gels with enhanced properties, which offers fundamentals and inspirations for the designing of various advanced functional materials.

Fabrication and Characterization of Agar- and Seaweed-Derived Biomembrane Films for Biomedical and Other Applications

This study focused on seaweed-based biomembrane development. The physical, mechanical, thermal, and biological properties of the fabricated films with different combinations of materials, such as agar, chitosan, poly(vinyl) alcohol (PVA), and quercetin, were characterized. The surface morphology of the films was analyzed using SEM. The maximum tensile strength (53.11 N/mm2), elongation at break (3.42%), and Young's modulus (15.52) of the biomembrane were recorded for the agar + chitosan combination. FT-Raman analysis confirmed the functional groups shift between the biopolymer and plasticizer used in this study. TG-DSC analysis of the biomembranes revealed a Tg in the range of 92.80°C-115°C. The maximum antioxidant activity was reported for quercetin (58.62%), and the maximum antimicrobial activity was observed for the chitosan and quercetin compounds against E. coli. A minimum hemolysis of 0.95% was achieved for the combination of agar + quercetin (AQ), agar + PEG (APE), Gracilaria corticata extract + PVA + quercetin (GCPQ) and agar + chitosan (AC) biomembranes. The minimum cytotoxicity of the biomembrane was 62.51% and 63.87% for Gracilaria corticata extract + PVA + quercetin (GCPQ), and agar + PVA, respectively. The proposed biomembrane films were found to be suitable for biomedical and packaging applications.

Tailoring the mechanical properties of macro-porous PVA hydrogels for biomedical applications

Polyvinyl alcohol (PVA) is a biocompatible biopolymer with superior dimensional and mechanical stability when compared to naturally available biomaterials such as collagen and gelatin. Furthermore, PVA in hydrogel form behaves non-linearly during mechanical loading, generating a response like soft biological tissues. Generally, PVA hydrogels are fabricated using freeze-thaw cycles (FTCs) and changing the number of FTCs gives control over its mechanical properties. Porosity of the hydrogel is another important factor which determines its mechanical properties and is also evident in biological soft tissues. Incorporating macro-pores in PVA hydrogels substantially reduces the stiffness of the material and can mimic some porous tissues such as lung, liver, bone marrow, kidneys, and penile tissues (corpus cavernosa and spongiosum). Within this study, we developed macro-porous PVA hydrogels using the freeze-thaw process followed by particulate leaching of sacrificial 3D-printed and milled PVA (m-PVA) filler particles. This fabrication method enables control over the porosity in macro-porous PVA hydrogels, which is crucial not only for tuning mechanical properties but also for mimicking the structure of spongy tissues, such as liver tissue and corpus cavernosum in the penis, for example. We investigated the level of porosity in the specimen using optical microscopy to understand the distribution of the pores and the pore size. The tunability of the mechanical properties of PVA hydrogels is a key finding of this study and is achieved using three factors: (i) weight percentage of sacrificial fillers, (ii) number of FTCs and (iii) concentration of PVA. These macro-porous PVA specimens have wide ranging biomedical applications as biological soft tissue analogues, or tissue engineering scaffolds, where the PVA hydrogel can be tuned to match the mechanical properties of these soft biological tissues.

Progress of AI assisted synthesis of polysaccharides-based hydrogel and their applications in biomedical field

Polymeric hydrogels, characterized by their highly hydrophilic three-dimensional network structures, boast exceptional physical and chemical properties alongside high biocompatibility and biodegradability. These attributes make them indispensable in various biomedical applications such as drug delivery, tissue engineering, wound dressings and sensor technologies. With the integration of artificial intelligence (AI), hydrogels are undergoing significant transformations in design, leveraging human-machine interaction, machine learning, neural networks, and 3D/4D printing technology. This article provides a concise yet comprehensive overview of polysaccharide-based hydrogels, exploring their intrinsic properties, functionalities, preparation techniques, and classifications, alongside their progress in biomedical research. Special emphasis is placed on AI-enhanced hydrogels, underscoring their transformative potential in redefining hydrogel performance and functionality. By integrating AI technologies, these intelligent hydrogels open unprecedented opportunities in precision medicine, adaptive biomaterials, and smart healthcare systems, highlighting promising directions for future research.

Eco-Friendly Hydrogels Loading Polyphenols-Composed Biomimetic Micelles for Topical Administration of Resveratrol and Rutin

In this study, we describe the development of hydrogel formulations composed of micelles loading two natural antioxidants-resveratrol and rutin-and the evaluation of the effect of a by-product on the rheological and textural properties of the developed semi-solids. This approach aims to associate the advantages of hydrogels for topical administration of drugs and of lipid micelles that mimic skin composition for the delivery of poorly water-soluble compounds in combination therapy. Biomimetic micelles composed of L-α-phosphatidylcholine loaded with two distinct polyphenols (one non-flavonoid and one flavonoid) were produced using hot shear homogenisation followed by the ultrasonication method. All developed micelles were dispersed in a carbomer 940-based hydrogel to obtain three distinct semi-solid formulations, which were then characterised by analysing the thermal, rheological and textural properties. Olive pomace-based hydrogels were also produced to contain the same micelles as an alternative to respond to the needs of zero waste and circular economy. The thermograms showed no changes in the typical profiles of micelles when loaded into the hydrogels. The rheological analysis confirmed that the produced hydrogels achieved the ideal properties of a semi-solid product for topical administration. The viscosity values of the hydrogels loaded with olive pomace (hydrogels A) proved to be lower than the hydrogels without olive pomace (hydrogels B), with this ingredient having a considerable effect in reducing the viscosity of the final formulation, yet without compromising the firmness and cohesiveness of the gels. The texture analysis of both hydrogels A and B also exhibited the typical behaviour expected of a semi-solid system.

Alginate Heterografted Copolymer Thermo-Induced Hydrogel Reinforced by PAA-g-P(boc-L-Lysine): Effects on Hydrogel Thermoresponsiveness

In this article, we report on the alginate heterografted by Poly(N-isopropyl acrylamide-co-N-tert-butyl acrylamide) and Poly(N-isopropyl acrylamide) (ALG-g-P(NIPAM86-co-NtBAM14)-g-PNIPAM) copolymer thermoresponsive hydrogel, reinforced by substituting part of the 5 wt% aqueous formulation by small amounts of Poly(acrylic acid)-g-P(boc-L-Lysine) (PAA-g-P(b-LL)) graft copolymer (up to 1 wt%). The resulting complex hydrogels were explored by oscillatory and steady-state shear rheology. The thermoresponsive profile of the formulations were affected remarkably by increasing the PAA-g-P(b-LL) component of the polymer blend. Especially, the sol-gel behavior altered to soft gel-strong gel behavior due to the formation of a semi-interpenetrating network based on the hydrophobic self-organization of the PAA-g-P(b-LL). In addition, the critical characteristics, namely Tc,thermothickening (temperature above which the viscosity increases steeply) and ΔT (transition temperature window), shifted and broadened to lower temperatures, respectively, due to the influence of the hydrophobic side chains P(b-LL) on the LCST of the PNIPAM-based grafted chains of the alginate. The effect of ionic strength was also examined, showing that this is another important factor affecting the thermoresponsiveness of the hydrogel. Again, the thermoresponsive profile of the hydrogel was changed significantly by the presence of salt. All the formulations showed self-healing capability and tolerance injectability, suitable for potential bioapplications in living bodies.

Calcium Cross-Linked Cellulose Nanofibrils: Hydrogel Design for Local and Controlled Nitric Oxide Release

Nitric oxide (NO) holds promise for wound healing due to its antimicrobial properties and role in promoting vasodilation and tissue regeneration. The local delivery of NO to target cells or organs offers significant potential in numerous biomedical applications, especially when NO donors are integrated into nontoxic viscous matrices. This study presents the development of robust cellulose nanofibril (CNF) hydrogels designed to control the release of nitric oxide (NO) generated in situ from a NO-donor molecule (S-nitrosoglutathione, GSNO) obtained from the nitrosation of its precursor molecule glutathione (GSH). CNF, efficiently isolated from sugar cane bagasse, exhibited a high aspect ratio and excellent colloidal stability in water. Although depletion forces could be observed upon the addition of GSH, this effect did not significantly alter the morphology of the CNF network at low GSH concentrations (<20 mM). Ionic cross-linking with Ca2+ resulted in nontoxic and robust hydrogels (elastic moduli ranging from 300 to 3000 Pa) at low CNF solid content. The release rate of NO from GSNO decreased in CNF from 1.61 to 0.40 mmol. L-1·h-1 when the nanofibril content raised from 0.3 to 1.0 wt %. The stabilization effect monitored for 16 h was assigned to hydrogel mesh size, which was easily tailored by modifying the concentration of CNF in the initial suspension. These results highlight the potential of CNF-based hydrogels in biomedical applications requiring a precise NO delivery.

Colorimetric IPN hydrogels embedded with colloidal photonic crystals: A novel approach for the detection of ethanol and Ba2+ ions in water

A critical bottleneck in sensor technology is the rapid and precise detection of specific analytes in complex matrices, hindering advancements in environmental monitoring, healthcare, and industrial process control. This study addresses this challenge by introducing a novel composite hydrogel sensor designed for rapid and selective detection of ethanol and barium ions (Ba2+) in aqueous environments. The sensor integrates interpenetrating network (IPN) hydrogels with embedded colloidal photonic crystals (CPCs), synthesized via a solution-based polymerization approach. This innovative configuration allows CPCs to dynamically adjust their photonic bandgap in response to environmental changes, manifesting as a visible, colorimetric shift. This response stems from the synergy between the mechanical properties of the IPN hydrogel and the optical sensitivity of CPCs. Upon exposure to analytes such as ethanol and Ba2+, the sensor exhibits a rapid and reversible color transition that is directly proportional to their concentration. Notably, ethanol (0 vol%-80 vol%) and Ba2+ (5-17.5 mM) induce a distinct blueshift in the photonic bandgap and trigger a color change from red-orange to green due to the alteration in the swelling behavior of the IPN hydrogel, affecting its lattice constant. The IPN hydrogel-CPC composite demonstrates exceptional operational stability and facilitates rapid detection, making it ideal for on-site applications without the need for complex equipment. These characteristics make the composite hydrogel sensor a promising candidate for environmental monitoring, industrial process control, and public health diagnostics, paving the way for the development of next-generation responsive sensor materials.