Progress on green crosslinking of polysaccharide hydrogels for drug delivery and tissue engineering applications

Combination of crosslinked zein film enhances the water barrier and mechanical properties of deacetylated konjac glucomannan/agar-based bilayer films

A bilayer strategy was employed to enhance the water-barrier properties of deacetylated konjac glucomannan/agar films by incorporating a crosslinked zein film using a layer-by-layer casting approach. SEM and Raman spectroscopy confirmed strong adhesion between the two layers, with the bilayer films fracturing as a single unit upon rupture, demonstrating successful fabrication of the deacetylated konjac glucomannan/agar-zein bilayer films. ATR-FTIR and 13C CPMAS NMR spectra revealed the esterification between the COOH groups of citric acid and the OH groups of zein, with the esterification degree increasing with up to 10 % critic acid. This reaction increased the crosslinking degree of zein, resulting in denser zein films and significantly improving water-barrier capacity from 29.86 to 8.09 × 10-13 g·m·m-2·s-1·Pa-1, as well as tensile strength from 12.39 MPa to 20.29 MPa. These findings provide insights into the development of macromolecule-based bilayer/multiplayer films with desired practical features for food packaging applications.

pH-responsive and self-adaptive injectable sodium alginate/carboxymethyl chitosan hydrogel accelerates infected wound healing by bacteriostasis and immunomodulation

Infected wound healing is a global medical challenge due to persistent bacterial infection and excess inflammation. Designing microenvironment-responsive and self-adaptive hydrogels with antibacterial and anti-inflammatory properties is expected to be an effective strategy to promote infected wound healing. In this study, a self-adaptive injectable sodium alginate/carboxymethyl chitosan hydrogel (SCSC) for pH-responsive release of curcumin has been prepared at room temperature by simple stirring. The incorporation of the crosslinker, Sr2+, enhances mechanical properties of SCSC hydrogel by tensing network structures, and provides synergistic biological activities. Meanwhile, SCSC hydrogel self-adapts in irregular wound shapes with outstanding ECM-like performance and releases effectively in the acidic microenvironment simulating the initial stage of infected wounds. SCSC hydrogel with good biocompatibility can promote cell migration, while relieving oxidative stress and mitochondria damage. Notably, SCSC hydrogel inhibits inflammatory factor expression and promotes M2 macrophage polarization by suppressing the NF-κB signaling pathway. Further, SCSC hydrogel significantly downregulates the over-expression of matrix metalloproteinase-9 (MMP-9), thereby helping promote ECM reconstruction. In vivo experiment results further demonstrate that SCSC hydrogel accelerates the re-epithelialization of infected wounds on the back of rats. Thus, the pH-responsive and self-adaptive SCSC hydrogel possesses great potential in the management and control of infected wounds.

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.

Mechanically robust, mouldable, dynamically crosslinked hydrogel flap with multiple functionalities for accelerated deep skin wound healing

Deep cutaneous wounds, which are difficult to heal and specifically occur on dynamic body surfaces, remain a substantial healthcare challenge in clinical practice because of multiple underlying factors, including excessive reactive oxygen species, potential bacterial infection, and extensive degradation of the extracellular matrix (ECM) which further leads to the progressive deterioration of the wound microenvironment. Any available individual wound therapy, such as antibiotic-loaded cotton gauze, cannot address all these issues. Engineering an advanced multifunctional wound dressing is the current need to promote the overall healing process of such wounds. Here, we report a multifunctional hydrogel flap primarily composed of biodegradable polymers gelatin (G) and poly-methyl vinyl ether-alt-maleic acid (MA) as the base material. The hydrogel physically incorporates tannic acid (TA) and vancomycin (V), for added functionality. The resulting hydrogel flap, gelatin- poly-methyl vinyl ether-alt-maleic acid-tannic acid-vancomycin (G-MA-TA-V/E-N), is formed through a chemical crosslinking process using EDC (E) and NHS (N). Thus, the hydrogel flap reveals multiple ideal properties that support its ease of application, including stretchability, porous microstructure (honey-comb structure), mouldability, and adhesiveness to multiple surfaces, including wet biological surfaces. The in vitro studies demonstrated strong antioxidant, antibacterial, and absorption properties essential for accelerated wound-healing applications. In vivo studies further reveal accelerated wound contraction and enhanced healing kinetics, promoting re-epithelialization, angiogenesis, and formation of apocrine glands. These findings underscore the efficacy and cost-effectiveness of fabricated hydrogel flaps as viable therapeutic options for treating deep skin wounds and make it worthwhile to integrate them with medical devices for tissue adhesion.

Fabrication of tannins and oat protein non-covalent complexes: Effect on the structure and in vitro digestion properties of oat proteins

This study explored the non-covalent interactions between oat protein isolate (OPI) and two tannic compounds-proanthocyanidins (PA) and tannic acid (TA)-and examined their impact on the structural and digestive properties of oat proteins. The combination of OPI with tannic compounds formed granular complexes with particle sizes ranging from 126 to 240 nm and zeta potentials between -35 and -44 mV. Compared to OPI alone, the α-helix and β-turn contents decreased, while the β-sheet and random coil contents increased in both OPI-tannin complexes. Fluorescence spectra analysis indicated that hydrogen bonding was the main interaction force in OPI-PA complexes, while OPI and TA were primarily bound by hydrophobic interactions. The simulated digestion analysis showed that the protein digestibility was delayed in the OPI-tannin complexes, likely due to the inhibition of digestive enzyme activity by tannic compounds, which slowed OPI digestibility. Additionally, the oxidation resistance of the OPI-tannin complexes significantly improved after in vitro digestion, indicating that the non-covalent complexes provided superior protection for the tannic compounds. These findings offer theoretical support for the design and utilization of oat- and tannin-rich foods.

Recent progress in biopolymer-based electrospun nanofibers and their potential biomedical applications: A review

Tissue engineering offers an alternative approach to developing biological substitutes that restore, maintain, or enhance tissue functionality by integrating principles from medicine, biology, and engineering. In this context, biopolymer-based electrospun nanofibers have emerged as attractive platforms due to their superior physicochemical properties, including excellent biocompatibility, non-toxicity, and desirable biodegradability, compared to synthetic polymers. Considerable efforts have been dedicated to developing suitable substitutes for various biomedical applications, with electrospinning receiving considerable attention as a versatile technique for fabricating nanofibrous platforms. While the applications of biopolymer-based electrospun nanofibers in the biomedical field have been previously reviewed, recent advancements in the electrospinning technique and its specific applications in areas such as bone regeneration, wound healing, drug delivery, and protein/peptide delivery remain underexplored from a material science perspective. This work systematically highlights the effects of biopolymers and critical parameters, including polymer molecular weight, viscosity, applied voltage, flow rate, and tip-to-collector distance, on the resulting nanofiber properties. The selection criteria for different biopolymers tailored to desired biomedical applications are also discussed. Additionally, the challenges and limitations associated with biopolymer-based electrospun nanofibers, alongside future perspectives for advancing their biomedical applications, are rationally analyzed.

A gelatin-chitosan-based film containing berberine hydrochloride/polypyrrole that promotes infectious wound healing through antibacterial and antioxidant properties, and electrical conductivity

Wound infections are a significant threat to human health. Therefore, the development of wound dressings with rapid antimicrobial properties is crucial to promote effective wound healing. In this study, chitosan (CS) was combined with gelatin (GE) to create an active film dressing (GC/BP) loaded with berberine hydrochloride (BH) and polypyrrole (PPY). After the incorporation of the bioactive materials, the film retained good mechanical properties, allowing it to withstand changes in the external environment of the wound. The antimicrobial effect of the GC/BP film exceeded 99 % after brief exposure to near-infrared light. In addition, the GC/BP film demonstrated a strong antioxidant effect with a DPPH clearance rate of 92.54 % within 48 h. In vivo experiments revealed that GC/BP films could enhance angiogenesis by upregulating the expression of the growth factor CD31, reducing oxidative stress by downregulating TNF-α expression, and accelerating the formation of fibrous tissues to promote wound healing. Importantly, the GC/BP film exhibited no cytotoxicity or hemolysis and demonstrated good biocompatibility. In conclusion, the GC/BP film is a safe and effective wound dressing with a promising potential for promoting wound healing.

Plant polyphenols inspired deep eutectic solvent functionalized boron nitride toward a high-performance cellulose-rich bamboo

The development of sustainable bamboo has received increasing attention owing to its excellent strength-to-weight ratio and environmental characteristics. However, the defects of mechanical properties, dimensional stability, and antibacterial activity of natural bamboo severely limit its practical application. Inspired by the catechol chemistry and ionic feature of mussels, a strong, tough, and antibacterial bamboo material is designed and developed by incorporating deep eutectic solvent (DES) functionalized boron nitride (BN) hybrids. Specifically, the functional DES is prepared from catechol gallic acid and cationic (meth)acrylic ammonium salts. Subsequently, efficient in-situ deposition of DES@BN hybrids on the bamboo is achieved through vacuum impregnation, photopolymerization technology, and temperature-assisted compression densification. The phenolic DES polymer not only provides a multiple chemical reaction platform for BN sheets, but also enhances the interfacial binding between BN and bamboo fibers through supramolecular interactions and catechol chemistry. The tensile and flexural strengths of the modified bamboo increase significantly to 236.8 and 218.4 MPa, which are 100.8 % and 61.7 % higher than the original sample. Additionally, the fabricated bamboo composites exhibit significantly enhanced dimensional stability and excellent antibacterial activity. This innovative and versatile strategy of fabricating high-performance bamboo shows great potential for application in sustainable building structures, decorative materials, and furniture production.

Study on network cross-linked hydrogel with cationic Bletilla striata polysaccharide/carbopol as a drug delivery system

In this study, we developed a novel cationic Bletilla striata polysaccharide (CBSP)/Carbopol ETD 2020 (CP) composite hydrogel matrix (CBSP-CP) for local drug delivery of traditional Chinese medicine formulations and compounds. This approach addresses the shortcomings of the existing commercial gel matrices in delivering complex components. We used molecular dynamics simulations to confirm the feasibility of crosslinking and compounding the polymer components. The structure of the composite was characterized using various traditional methods, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The composite polyelectrolyte hydrogel prepared through electrostatic interactions between CBSP and CP exhibited favorable rheological properties, excellent ion resistance stability, and good skin adaptability. Furthermore, the safety of the gel matrix was validated using cytotoxicity and skin irritation tests. In summary, the CBSP-CP gel matrix not only enhanced ion resistance compared to current commercial gel matrices but also expanded its applicability for the local delivery of complex components, such as traditional Chinese medicine formulations and compounds.

Development of Scalable Elastic Gelatin Hydrogel Films Crosslinked with Waterborne Polyurethane for Enhanced Mechanical Properties and Strain Recovery

Exploiting novel crosslinking chemistry, this study pioneers the use of waterborne polyurethane (WPU) to chemically crosslink porcine-derived gelatin, producing enhanced gelatin hydrogel films through a solvent-casting method. Our innovative approach harnesses the reactive isocyanate groups of WPU, coupling them effectively with gelatin's hydroxyl and primary amino groups to form robust urea and urethane linkages within the hydrogel matrix. This method not only preserves the intrinsic elasticity of polyurethane but also significantly augments the films' tensile strength and strain. Comprehensive characterizations of these hydrogel films and pre-formed hydrogel reaction mixtures were conducted using viscosity measurements, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and the universal testing machine (UTM) for tensile-recovery assessments, alongside evaluations of their biocompatibility. The results demonstrated a reduction in pore size with an increase in WPU concentration from 2 to 6% in the developed hydrogels with a decrease in the equilibrium swelling ratio from 15% to 9%, respectively. Further, hydrogels with 6% WPU exhibited the highest tensile stress in both a dry and wet state. The gelatin hydrogel formed with 6% WPU blend also demonstrated the growth and proliferation of CCD-986K (fibroblast) and CCD-1102 (keratinocyte) cells for up to 5 days of co-culturing. The results indicate a notable enhancement in the mechanical properties and biocompatibility of gelatin hydrogels upon the introduction of WPU, positioning these films as superior candidates for biomedical applications such as tissue engineering and wound dressing.

Chitosan-BODIPY fluorescent composite materials for photodynamical antibacterial and therapy

Chitosan-based fluorescent copolymers containing borodipyrromethene (BODIPY) were synthesized and investigated. In this work, fluorescent compound (BOD-4) containing -C ≡ CH was synthesized firstly. Subsequently, chitosan (CS)-based polymer CS-I was obtained through the -NH2/-C ≡ C click reaction between BOD-4 and CS. Thirdly, CS-Py was prepared via Suzuki reaction between CS-I and pyridine. Finally, the synthesis of macromolecular photosensitizers, i.e. CS-Me and CS-Bn, was achieved by pyridinium salt formation. CS-Me and CS-Bn could produce reactive oxygen species (ROS) when exposed to white light, demonstrating superior light utilization efficiency. This strategy not only utilizes the photodynamic ability of photosensitizing molecules but also takes advantage of chitosan's biocompatibility and antibacterial efficacy. The photodynamic antimicrobial activities of the macromolecular photosensitizers have been tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). CS-Me and CS-Bn exhibited not only the inherent antibacterial properties but also photodynamic capabilities, which significantly enhance their antibacterial effectiveness. Under white light irradiation, bacteria can be effectively eradicated. When made into a film by loading CS-Me and CS-Bn onto transparent band-aid, excellent photodynamic antibacterial properties were obtained. CS-based photosensitizers maintain the biocompatibility and antibacterial properties of CS. In addition, they expand the scope of chitosan's application in photodynamic therapy (PDT) as well.

Recent advances in polysaccharide-based drug delivery systems for cancer therapy: a comprehensive review

Cancer has a high rate of incidence and mortality throughout the world. Although several conventional approaches have been developed for the treatment of cancer, such as surgery, chemotherapy, radiotherapy and thermal therapy, they have remarkable disadvantages which result in inefficient treatment of cancer. For example, immunogenicity, prolonged treatment, non-specificity, metastasis and high cost of treatment, are considered as the major drawbacks of chemotherapy. Therefore, there is a fundamental requirement for the development of breakthrough technologies for cancer suppression. Polysaccharide-based drug delivery systems (DDSs) are the most reliable drug carriers for cancer therapy. Polysaccharides, as a kind of practical biomaterials, are divided into several types, including chitosan, alginates, dextran, hyaluronic acid, cyclodextrin, pectin, etc. Polysaccharides are extracted from different natural resources (like herbal, marine, microorganisms, etc.). The potential features of polysaccharides have made them reliable candidates for therapeutics delivery to cancer sites; the simple purification, ease of modification and functionalization, hydrophilicity, serum stability, appropriate drug loading capacity, biocompatibility, bioavailability, biodegradability and stimuli-responsive and sustained drug release manner are considerable aspects of these biopolymers. This review highlights the practical applications of polysaccharides-based DDSs in pharmaceutical science and cancer therapy.

A multifunctional and tough lotus root starch-based bio-photonic hydrogel for stretchable fabric pattern color change and water rewriting

Photonic crystal hydrogels (PCHs) are innovative materials that translate imperceptible deformations and humidity changes into visible colors, broadening the applications of photonics in bioengineering and smart materials. To overcome poor mechanical properties of traditional PCHs limited by weak intermolecular forces, we designed a PCH with a dual-network framework comprising N-isopropylacrylamide-co-acrylamide (NIPAM-co-AM) and biomass lotus root starch (LR). Since LR is rich in hydroxyl groups, it can undergo molecular linkage entanglement with the NIPAM-co-AM hydrogel matrix, forming hydrogen bonds that significantly enhance the mechanical properties of the PCH. We have prepared PCH films capable of conveying multidimensional information about the extent and distribution of transient deformation by encapsulating magnetic photonic crystal microspheres (MPCMs) within a hydrogel matrix. The PCH films were found to have ultrafast response time (< 10 s), full-color tunable range, high spatial resolution, excellent mechanical toughness (tensile up to 0.17 MPa) and sensitivity (2.52 nm %-1), and were able to sense relative humidity (RH) from 11 % to 98 %. Equipped with a dynamically reconfigurable lattice, this dual-responsive (tensile/humidity) PCH not only facilitates the creation of water-rewritable photonic films but also holds promise for integration into structural color elastic fabrics, thereby presenting novel prospects for smart textile applications.

Two Novel Membranes Based on Collagen and Polyphenols for Enhanced Wound Healing

Two novel membranes based on collagen and two polyphenols, taxifolin pentaglutarate (TfG5) and a conjugate of taxifolin with glyoxylic acid (DfTf), were prepared. Fourier transform infrared spectroscopy examination confirmed the preservation of the triple helical structure of collagen. A scanning electron microscopy study showed that both materials had a porous structure. The incorporation of DfTf into the freeze-dried collagen matrix increased the aggregation of collagen fibers to a higher extent than the incorporation of TfG5, resulting in a more compact structure of the material containing DfTf. It was found that NIH/3T3 mouse fibroblasts were attached to, and relatively evenly spread out on, the surface of both newly obtained membranes. In addition, it was shown that the membranes enhanced skin wound healing in rats with a chemical burn induced by acetic acid. The treatment with the materials led to a faster reepithelization and granulation tissue formation compared with the use of other agents (collagen without polyphenols and buffer saline). It was also found that, in the wound tissue, the level of thiobarbituric acid reactive substances (TBARS) was significantly higher and the level of low-molecular-weight SH-containing compounds (RSH) was significantly lower than those in healthy skin, indicating a rise in oxidative stress at the site of injury. The treatment with collagen membranes containing polyphenols significantly decreased the TBARS level and increased the RSH level, suggesting the antioxidant/anti-inflammatory effect of the materials. The membrane containing TfG5 was more effective than other ones (the collagen membrane containing DfTf and collagen without polyphenols). On the whole, the data obtained indicate that collagen materials containing DfTf and TfG5 have potential as powerful therapeutic agents for the treatment of burn wounds.

The pH-sensitive chondroitin sulphate-based nanoparticles for co-delivery of doxorubicin and berberine enhance the treatment of breast cancer

In the tumor microenvironment (TME), cancer associated fibroblasts (CAFs) facilitate drug resistance and tumor metastasis. Therefore, more and more attention has been focused on the regulation of TME by preventing the cross-talk between tumor cells and CAFs in the treatment of breast cancer. In this study, we have combined the benefits of deep drug penetration, pH sensitivity, and tumor-targeting delivery to prepare chondroitin sulphate (CS)-based nanomicelles (BBR/CS-DOX) for the co-delivery of doxorubicin (DOX) and berberine (BBR). A unique MCF-7 + MRC-5 co-cultured cell model and 4 T1 + NIH3T3 co-implanted mice model, were established to simulate the TME of breast cancer (BC). As expected, BBR/CS-DOX could accumulate in tumor egion, be taken up by both tumor cells and CAFs, and improve drug absorption and retention. Compared with free drugs, BBR/CS-DOX demonstrated stonger pro-apoptotic and anti-metastatic effect in vitro and in vivo, respectively the histological studies showed that BBR/CS-DOX efficiently prevented the activation of fibroblasts, inhibited extracellular matrix (ECM) deposition, and decreased tumor angiogenesis, showing superior anti-tumor efficacy. In summary, BBR/CS-DOX has the potential to significantly enhance the therapeutic effect of breast cancer through inhibiting the "CAFs-tumor cells" crosstalk, and has promising clinical application prospects.

Tragacanth gum hydrogels with cellulose nanocrystals: A study on optimizing properties and printability

This study investigates a novel all-polysaccharide hydrogel composed of tragacanth gum (TG) and cellulose nanocrystals (CNCs), eliminating the need for toxic crosslinkers. Designed for potential tissue engineering applications, these hydrogels were fabricated using 3D printing and freeze-drying techniques to create scaffolds with interconnected macropores, facilitating nutrient transport. SEM images revealed that the hydrogels contained macropores with a diameter of 100-115 μm. Notably, increasing the CNC content within the TG matrix (30-50 %) resulted in a decrease in porosity from 83 % to 76 %, attributed to enhanced polymer-nanocrystal interactions that produced denser networks. Despite the reduced porosity, the hydrogels demonstrated high swelling ratios (890-1090 %) due to the high water binding capacity of the hydrogel. Mechanical testing showed that higher CNC concentrations significantly improved compressive strength (27.7-49.5 kPa) and toughness (362-707 kJ/m3), highlighting the enhanced mechanical properties of the hydrogels. Thermal analysis confirmed stability up to 400 °C and verified ionic crosslinking with CaCl₂. Additionally, hemolysis tests indicated minimal hemolytic activity, affirming the biocompatibility of the TG/CNC hydrogels. These findings highlight the potential of these hydrogels as advanced materials for 3D-printed scaffolds and injectable hydrogels, offering customizable porosity, superior mechanical strength, thermal stability, and biocompatibility.

Plant-Derived Chinese Herbal Hydrogel Microneedle Patches for Wound Healing

Several natural Chinese herbal medicines have demonstrated considerable potential in facilitating wound healing, while the primary concern remains centered around optimizing formulation and structure to maximize their efficacy. To address this, a natural microneedles drug delivery system is proposed that harnesses gelatinized starch and key Chinese herbal ingredients-aloe vera and berberine. After gelatinized and aged in a well-designed mold, the starch-based microneedles are fabricated with suitable mechanical strength to load components. The resulting Chinese herbal hydrogel microneedles, enriched with integrated berberine and aloe, exhibit antibacterial, anti-inflammatory, and fibroblast growth-promoting properties, thereby facilitating wound healing in the whole process. In vivo experimental results underscore the notable achievements of the microneedles in early-stage antibacterial effects and subsequent tissue reconstruction, contributing significantly to the overall wound healing process. These results emphasize the advantageous combination of traditional Chinese medicine with microneedles, presenting a novel strategy for wound repair and opening new avenues for the application of traditional Chinese medicine.

Oxidized ionic polysaccharide hydrogels: Review on derived scaffolds characteristics and tissue engineering applications

Polysaccharide-based hydrogels have gained prominence due to their non-toxicity, biocompatibility, and structural adaptability for constructing tissue engineering scaffolds. Polysaccharide crosslinking is necessary for hydrogel stability in vivo. The periodate oxidation enables the modification of native polysaccharide characteristics for wound healing and tissue engineering applications. It produces dialdehydes, which are used to crosslink biocompatible amine-containing macromolecules such as chitosan, gelatin, adipic acid dihydrazide, silk fibroin, and peptides via imine/hydrazone linkages. Crosslinked oxidized ionic polysaccharide hydrogels have been studied for wound healing, cardiac and liver tissue engineering, bone, cartilage, corneal tissue regeneration, abdominal wall repair, nucleus pulposus regeneration, and osteoarthritis. Several modified hydrogel systems have been synthesized using antibiotics and inorganic substances to improve porosity, mechanical and viscoelastic properties, desired swelling propensity, and antibacterial efficacy. Thus, the injectable hydrogels provide a host-tissue-mimetic environment with high cell adhesion and viability, making them appropriate for scarless wound healing and tissue engineering applications. This review describes the oxidation procedure for alginate, hyaluronic acid, gellan gum, pectin, xanthan gum and chitosan, as well as the characteristics of the resulting materials. Furthermore, a critical review of scientific advances in wound healing and tissue engineering applications has been provided.

Decellularized Macroalgae as Complex Hydrophilic Structures for Skin Tissue Engineering and Drug Delivery

Due to their indisputable biocompatibility and abundant source, biopolymers are widely used to prepare hydrogels for skin tissue engineering. Among them, cellulose is a great option for this challenging application due to its increased water retention capacity, mechanical strength, versatility and unlimited availability. Since algae are an unexploited source of cellulose, the novelty of this study is the decellularization of two different species, freshly collected from the Black Sea coast, using two different chemical surfactants (sodium dodecyl sulphate and Triton X-100), and characterisation of the resulted complex biopolymeric 3D matrices. The algae nature and decellularization agent significantly influenced the matrices porosity, while the values obtained for the hydration degree included them in hydrogel class. Moreover, their capacity to retain and then controllably release an anti-inflammatory drug, ibuprofen, led us to recommend the obtained structures as drug delivery systems. The decellularized macroalgae hydrogels are bioadhesive and cytocompatible in direct contact with human keratinocytes and represent a great support for cells. Finally, it was noticed that human keratinocytes (HaCaT cell line) adhered and populated the structures during a monitoring period of 14 days.

Experimental and Modelling Study of Controlled Release from Dextran-Based Cryogels

In this work, five different dextran-based cryogels for controlled drug release are investigated. Vitamin B12 was used as a model drug for in vitro release tests. Two different drug-loading procedures were adopted, leading to very different drug release curves. Indeed, a fast Fickian release was observed when freeze-dried samples of DEX40PEG360MA and DEX40PEG500MA were infused with the drug after cryogel formation. On the contrary, a slowed highly non-Fickian behavior arises when the drug is loaded before the low-temperature crosslinking step, leading to the cryogel formation. The non-Fickian drug release, observed for all the five different dextran-based cryogels investigated, is actually due to the cryoconcentration phenomenon, modeled with a two-step release process. The proposed transport model accurately predicts experimental release curves characterized by a long lag time, confirming that dextran-based cryogels are suitable for controlled release.

Impact of a Bio-Cross-Linking Agent Obtained from Spent Coffee Grounds on the Physicochemical and Thermal Properties of Gelatin/Κ-Carrageenan Hydrogels

Gelatine hydrogels can be prepared using different cross-linking methods, such as enzymatic, physical or chemical. Unfortunately, in the case of chemical cross-linking, the typically utilized synthetic cross-linkers are harmful to human health and the environment. Therefore, in accordance with the principles of green chemistry and sustainable development, we have obtained compounds for the chemical cross-linking of hydrogel polymers from the processing of spent coffee grounds. In this study, gelatin/κ-carrageenan hydrogels are cross-linked using a bio-cross-linking agent from spent coffee grounds. Their physicochemical and thermal properties are compared with those of standard physical gels. The chemical cross-linking was confirmed based on FT-IR spectra, which demonstrated the formation of new covalent bonds between the oxidized polyphenols included in the extract from the spent coffee grounds and the amide groups present in the gelatine structure. Significant differences were also observed in morphology (SEM images) and other physico-chemical characteristics (gel fraction, swelling ability, hardness). The chemically cross-linked hydrogels in comparison to physically ones are characterized by a better developed porous network, a slightly higher gel fraction (64.03 ± 4.52% as compared to 68.15 ± 0.77%), and a lower swelling ratio (3820 ± 45% as compared to 1773 ± 35%), while TGA results show that they have better thermal stability. The research confirmed the possibility of using the developed natural cross-linking agent in the process of obtaining hydrogel materials based on bio-polymers.

Cyanobacterial Ampholyte Hydrogels Developed by the Cationization of Sulfated Polysaccharides and Their Cell-Compatibility

Sacran is a cyanobacterial supergiant polysaccharide with carboxylate and sulfate groups that exhibits antiallergic and antiinflammatory properties. However, its high anionic functions restrict cell compatibility. Quaternary ammonium groups were substituted to form sacran ampholytes, and the cell compatibility of the cationized sacran hydrogels was evaluated. The cationization process involved the reaction of N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride with the primary amine or hydroxyl groups of sacran. The degree of cationization ranged from 32 to 87% for sugar residues. Hydrogels of sacran ampholytes were prepared by annealing their dried sheets by thermal cross-linking; these hydrogels exhibited anisotropic expansion properties. The water contact angle on the hydrogels decreased from 26.5 to 15.3° with an increase in the degree of cationization, thereby enhancing hydrophilicity. The IC50 values of sacran ampholytes decreased with an increased degree of cationization, resulting in a reduction in cytotoxicity toward the L-929 mouse fibroblast cell line. This reduction was associated with an increase in the cell proliferation density after 3 days of incubation. Scanning electron microscopy images showed fibroblast intercellular connections. Therefore, the sacran ampholyte hydrogel exhibited increased hydrophilicity and cell compatibility, which is beneficial for various biomedical applications.

The Role of Superabsorbent Polymers and Polymer Composites in Water Resource Treatment and Management

In the last century, the issue of "water reserves" has become a remarkably strategic topic in modern science and technology. In this context, water resource treatment and management systems are being developed in both agricultural and urban area scenarios. This can be achieved using superabsorbent polymers (SAPs), highly cross-linked hydrogels with three-dimensional, hydrophilic polymer structures capable of absorbing, swelling and retaining huge amounts of aqueous solutions. SAPs are able to respond to several external stimuli, such as temperature, pH, electric field, and solution composition and concentration. They can be used in many areas, from sensor technology to drug delivery, agriculture, firefighting applications, food, and the biomedical industry. In addition, new categories of functional SAP-based materials, mainly superabsorbent polymer composites, can also encapsulate fertilizers to efficiently provide the controlled release of both water and active compounds. Moreover, SAPs have great potential in wastewater treatment for the removal of harmful elements. In this respect, in the following review, the most promising and recent advances in the use of SAPs and composite SAPs as tools for the sustainable management and remediation of water resource are reviewed and discussed by identifying opportunities and drawbacks and highlighting new challenges and aims to inspire the research community.

Hydrogel-Based Therapies for Ischemic and Hemorrhagic Stroke: A Comprehensive Review

Stroke remains the second leading cause of death and a major cause of disability worldwide, significantly impacting individuals, families, and healthcare systems. This neurological emergency can be triggered by ischemic events, including small vessel arteriolosclerosis, cardioembolism, and large artery atherothromboembolism, as well as hemorrhagic incidents resulting from macrovascular lesions, venous sinus thrombosis, or vascular malformations, leading to significant neuronal damage. The resultant motor impairment, cognitive dysfunction, and emotional disturbances underscore the urgent need for effective therapeutic interventions. Recent advancements in biomaterials, particularly hydrogels, offer promising new avenues for stroke management. Hydrogels, composed of three-dimensional networks of hydrophilic polymers, are notable for their ability to absorb and retain substantial amounts of water. Commonly used polymers in hydrogel formulations include natural polymers like alginate, chitosan, and collagen, as well as synthetic polymers such as polyethylene glycol (PEG), polyvinyl alcohol (PVA), and polyacrylamide. Their customizable characteristics-such as their porosity, swelling behavior, mechanical strength, and degradation rates-make hydrogels ideal for biomedical applications, including drug delivery, cell delivery, tissue engineering, and the controlled release of therapeutic agents. This review comprehensively explores hydrogel-based approaches to both ischemic and hemorrhagic stroke therapy, elucidating the mechanisms by which hydrogels provide neuroprotection. It covers their application in drug delivery systems, their role in reducing inflammation and secondary injury, and their potential to support neurogenesis and angiogenesis. It also discusses current advancements in hydrogel technology and the significant challenges in translating these innovations from research into clinical practice. Additionally, it emphasizes the limited number of clinical trials utilizing hydrogel therapies for stroke and addresses the associated limitations and constraints, underscoring the need for further research in this field.

Chitin nanofibrils assisted 3D printing all-chitin hydrogels for wound dressing

The direct ink writing technique used in 3D printing technology is generally applied to designing biomedical hydrogels. Herein, we proposed a strategy for preparing all-chitin-based inks for wound dressing via direct ink writing technique. The β-chitin nanofibers (MACNF) with a high aspect ratio were applied as a nanofiller to modulate the rheological properties of the alkaline dissolved chitin solution. The printing fidelity significantly depends on the MACNF introduction amount to the composite ink. 5-10 wt% MACNF ratio showed superior printing performance. The printed scaffold showed a uniform micron-sized pore structure and a woven network of nanofibers. Due to the good biocompatibility of chitin and the stereoscopic spatial skeleton, this scaffold showed excellent performance as a wound dressing, which can promote cell proliferation, collagen deposition and the angiogenesis of wounds, demonstrating its potential in biomedical applications. This approach successfully balanced the chitinous printability and biofunctions.

Orally ingestible medication utilizing layered double hydroxide nanoparticles strengthened alginate and hyaluronic acid-based hydrogel bead for bowel disease management

In the treatment of bowel diseases such as ulcerative colitis through oral administration, an effective drug delivery system targeting the colon is crucial for enhancing efficacy and minimizing side effects of therapeutic agents. This study focuses on the development of a novel nanocomposite hydrogel bead comprising a synergistic blend of biological macromolecules, namely sodium alginate (ALG) and hyaluronic acid (HA), reinforced with layered double hydroxide nanoparticles (LDHs) for the oral delivery of dual therapeutics. The synthesized hydrogel bead exhibits significantly enhanced gel strength and controllable release of methylprednisolone (MP) and curcumin (CUR), serving as an anti-inflammatory drug and a mucosal healing agent, compared to native ALG or ALG/HA hydrogel beads without LDHs. The physicochemical properties of the synthesized LDHs and hydrogel beads were characterized using various techniques, including scanning electron microscopy, zeta potential measurement, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. In vitro release studies of MP and CUR under simulated gastrointestinal tract (GIT) conditions demonstrate the superior controlled release property of the nanocomposite hydrogel bead, particularly in minimizing premature drug release in the upper GIT environment while sustaining release of over 82 % of drugs in the colonic environment. Thus, the modularly engineered carrier designed for oral colon targeting holds promise as a potential candidate for the treatment of ulcerative colitis.

Nanocellulose-assisted mechanically tough hydrogel platforms for sustained drug delivery

The controlled delivery of the desired bioactive molecules is required to achieve the maximum therapeutic effects with minimum side effects. Biopolymer-based hydrogels are ideal platforms for delivering the desired molecules owing to their superior biocompatibility, biodegradability, and low-immune response. However, the prolonged delivery of the drugs through biopolymer-based hydrogels is restricted due to their weak mechanical stability. We developed mechanically tough and biocompatible hydrogels to address these limitations using carboxymethyl chitosan, sodium alginate, and nanocellulose for sustained drug delivery. The hydrogels were cross-linked through calcium ions to enhance their mechanical strength. Nanocellulose-added hydrogels exhibited improved mechanical strength (Young's modulus; 23.36 → 30.7 kPa, Toughness; 1.39 → 5.65 MJm-3) than pure hydrogels. The composite hydrogels demonstrated increased recovery potential (66.9 → 84.5 %) due to the rapid reformation of damaged polymeric networks. The hydrogels were stable in an aqueous medium and demonstrated reduced swelling potential. The hydrogels have no adverse effects on embryonic murine fibroblast (3 T3), showing their biocompatibility. No bacterial growth was observed in hydrogels-treated groups, indicating their antibacterial characteristics. The sustained drug released was observed from nanocellulose-assisted hydrogel scaffolds compared to the pure polymer hydrogel scaffold. Thus, hydrogels have potential and could be used as a sustained drug carrier.

Microscopic and Macroscopic Characterization of Hydrogels Based on Poly(vinyl-alcohol)-Glutaraldehyde Mixtures for Fricke Gel Dosimetry

In recent decades, hydrogels have emerged as innovative soft materials with widespread applications in the medical and biomedical fields, including drug delivery, tissue engineering, and gel dosimetry. In this work, a comprehensive study of the macroscopic and microscopic properties of hydrogel matrices based on Poly(vinyl-alcohol) (PVA) chemically crosslinked with Glutaraldehyde (GTA) was reported. Five different kinds of PVAs differing in molecular weight and degree of hydrolysis were considered. The local microscopic organization of the hydrogels was studied through the use of the 1H nuclear magnetic resonance relaxometry technique. Various macroscopic properties (gel fraction, water loss, contact angle, swelling degree, viscosity, and Young's Modulus) were investigated with the aim of finding a correlation between them and the features of the hydrogel matrix. Additionally, an optical characterization was performed on all the hydrogels loaded with Fricke solution to assess their dosimetric behavior. The results obtained indicate that the degree of PVA hydrolysis is a crucial parameter influencing the structure of the hydrogel matrix. This factor should be considered for ensuring stability over time, a vital property in the context of potential biomedical applications where hydrogels act as radiological tissue-equivalent materials.