Structure Of Hydrogels Research Articles

Bilayer 3D co‐culture platform inducing the differentiation of normal fibroblasts into cancer‐associated fibroblast like cells: New in vitro source to obtain cancer‐associated fibroblasts

AbstractThis study presents a novel in vitro bilayer 3D co‐culture platform designed to obtain cancer‐associated fibroblasts (CAFs)‐like cells. The platform consists of a bilayer hydrogel structure with a collagen/polyethylene glycol (PEG) hydrogel for fibroblasts as the upper layer and an alginate hydrogel for tumor cells as the lower layer. The platform enabled paracrine interactions between fibroblasts and cancer cells, which allowed for selective retrieval of activated fibroblasts through collagenase treatment for further study. Fibroblasts remained viable throughout the culture periods and showed enhanced proliferation when co‐cultured with cancer cells. Morphological changes in the co‐cultured fibroblasts resembling CAFs were observed, especially in the 3D microenvironment. The mRNA expression levels of CAF‐related markers were significantly upregulated in 3D, but not in 2D co‐culture. Proteomic analysis identified upregulated proteins associated with CAFs, further confirming the transformation of normal fibroblasts into CAF within the proposed 3D co‐culture platform. Moreover, co‐culture with CAF induced radio‐ and chemoresistance in pancreatic cancer cells (PANC‐1). Survival rate of cancer cells post‐irradiation and gemcitabine resistance increased significantly in the co‐culture setting, highlighting the role of CAFs in promoting cancer cell survival and therapeutic resistance. These findings would contribute to understanding molecular and phenotypic changes associated with CAF activation and provide insights into potential therapeutic strategies targeting the tumor microenvironment.

Coaxial nozzle-assisted electrohydrodynamic printing for microscale 3D cell-laden constructs.

Cell printing has found wide applications in biomedical fields due to its unique capability in fabricating living tissue constructs with precise control over cell arrangements. However, it is still challenging to print cell-laden 3D structures simultaneously with high resolution and high cell viability. Here a coaxial nozzle-assisted electrohydrodynamic cell printing strategy was developed to fabricate living 3D cell-laden constructs. Critical process parameters such as feeding rate and stage moving speed were evaluated to achieve smaller hydrogel filaments. The effect of CaCl2 feeding rate on the printing of 3D alginate hydrogel constructs was also investigated. The results indicated that the presented strategy can print 3D hydrogel structures with relatively uniform filament dimension (about 80 μm) and cell distribution. The viability of the encapsulated cells was over 90%. We envision that the coaxial nozzle-assisted electrohydrodynamic printing will become a promising cell printing strategy to advance biomedical innovations.

Carbon dots-facilitated on-demand dissolution of Ca-alginate hydrogel via site-specific mineralization for wound healing

On-demand dissolution of hydrogels has shown much potential in easy and pain-free removal of wound dressings. This work firstly describes a type of carbon dots (CDs) for dissolving Ca-alginate hydrogel via site-specific mineralization method. The CDs were characterized by two features, which included presence of primary/secondary amine groups and generation of calcium crystals with Ca2+. Especially, the amount of primary/secondary amine groups on CDs played key role in determining whether hydrogel could be dissolved. When there were sufficient primary/secondary amine groups, the mineralization occurred on CDs rather than alginates due to the hydrogen bond between primary/secondary amine and carboxyl of alginates. Thereby, this promoted the gel-sol transition through Ca2+ capture from the hydrogels. Moreover, antibacterial test revealed Ca2+ capture from cell walls, while in vivo test revealed hypoxia relief due to porous structures of the renewed hydrogels. Overall, CDs with sufficient primary/secondary amine groups could dissolve Ca-alginate hydrogel through site-specific mineralization method, accompanying by additional functions of antibacterial and hypoxia relief.Graphical

Migration of copper(II) ions in humic systems—effect of incorporated calcium(II), magnesium(II), and iron(III) ions

The mobility of heavy metals in natural soil systems can be affected by the properties and compositions of those systems: the content and quality of organic matter as well as the character of inorganic constituents. In this work, the diffusion of copper(II) ions in humic hydrogels with incorporated calcium(II), magnesium(II), and iron(III) ions was investigated. The methods of instantaneous planar source and of constant source were used. Experimental data yielded the time development of the concentration in hydrogels and the values of effective diffusion coefficients. The coefficients include both the influence of the hydrogel structure and the interaction of diffusing particles with the hydrogel. Our results showed that the presence of natural metal ions such as calcium, magnesium, or iron can strongly affect the diffusivity of copper in humic systems. They indicate that the mobility of copper ions depends on their concentration. The mobility can be supported by higher contents of copper in the system. While the incorporation of Ca and Mg resulted in the decrease in the diffusivity of copper ions, the incorporation of Fe(III) into humic hydrogel resulted in an increase in the diffusivity of Cu(II) in the hydrogel in comparison with pure humic hydrogel.

Efficient adsorption of cationic dyes by a novel honeycomb-like porous hydrogel with ultrahigh mechanical property

The optimization of hydrogel structure is crucial for adsorption capacity, mechanical stability, and reusability. Herein, a chitosan and laponite-XLS co-doped poly(acrylic acid-co-acrylamide) hydrogel (CXAA) with honeycomb-like porous structures is synthesized by cooperative cross-linking of 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) and laponite-XLS in reticular frameworks of acrylic acid (AAc) and acrylamide (AM). The CXAA exhibits extraordinary mechanical performances including tough tensile strength (3.36 MPa) and elasticity (2756 %), which facilitates recycling in practical adsorption treatment and broadens potential applications. Since the regular porous structures can fully expose numerous adsorption sites and electronegative natures within polymer materials, CXAA displays efficient and selective adsorption properties for cationic dyes like methylene blue (MB) and malachite green (MG) from mixed pollutants and can reach record-high values (MB = 6886 mg g−1, MG = 11,381 mg g−1) compared with previously reported adsorbents. Therefore, CXAA exhibits promising potential for separating cationic and anionic dyes by their charge disparities. Mechanism studies show that the synergistic effects of HACC, laponite-XLS, and functional groups in monomers promote highly efficient adsorption. Besides, the adsorption capacity of CXAA remains stable even after undergoing five cycles of regeneration. The results confirm that CXAA is a promising adsorbent for effectively removing organic dyes in wastewater.

Therapeutic efficacy of Strobilanthes urticifolia-infused pectin/polyacrylic acid hydrogel for targeted hepatorenal fibrosis mitigation: A multifaceted biomaterial approach.

Pectin/polyacrylic acid (PPAA) hydrogel is a unique and versatile biomaterial with applications in drug delivery, wound healing, tissue engineering, and agriculture, owing to its tailored properties and multifunctional attributes. This study aims to harness the therapeutic potential of Strobilanthes urticifolia extract within a PPAA hydrogel matrix to attenuate liver and kidney fibrosis through targeted and sustained delivery of biologically active substances. PPAA hydrogel was prepared by free radical polymerization, followed by its porosity and swelling determination. The results depicted the porous nature of PPAA hydrogel and improved swelling properties at pH 7.4, confirming its drug delivery promise. The polyphenolic-enriched S. urticifolia extracts of leaf and flower were loaded onto PPAA hydrogel, and the loading efficiency was 87% (leaf) and 62.5% (flower). Moreover, slow-release studies showed controlled and prolonged release of polyphenols for 7 days. The polyphenolic-enriched hydrogel's microstructure was characterized using SEM, FTIR, and thermogravimetric analysis (TGA). SEM results revealed a highly porous structure of polyphenol enriched PPAA hydrogel, while FTIR analysis confirmed the presence of functional groups such as OH group of carboxylic acid, aliphatic CH2 stretching due to acrylic acid grafting with pectin, CO stretching due to acid linkage with pectin, CH of aromatic ring, and CH of carboxylate salt in PPAA hydrogel. TGA of PPAA hydrogel showed its stability up to 488°C. Additionally, the S. urticifolia extract loaded PPAA hydrogel displayed significant antibacterial properties and minimum inhibitory concentrations against both Gram-positive and Gram-negative bacteria. In vivo studies carried out on rats demonstrated that polyphenolic enriched PPAA hydrogel significantly attenuates liver and kidney fibrosis. Therefore, it is concluded from the present study that loading of polyphenolic enriched extract from leaves and flower of S. urticifolia enhanced the biomedical applications of PPAA hydrogel. RESEARCH HIGHLIGHTS: The PPAA hydrogel developed in this study exhibits a highly porous structure and improved swelling properties at physiological pH (7.4), making it an excellent candidate for drug delivery systems. S. urticifolia extracts, rich in polyphenols, were successfully incorporated into the PPAA hydrogel with high loading efficiencies of 87% for leaf and 62.5% for flower extracts. Loading of polyphenolic enriched extracts of S. urticifolia onto PPAA enhanced its biological activities such as antibacterial, hepatoprotective, and reno-protective activities as depicted by in vitro and in vivo studies.

Synthesis of thermally and pH-responsive poly(2-(dimethylamino)ethyl methacrylate)-based hydrogel reinforced with cellulose nanocrystals for sustained drug release

Hydrogels are widely employed in biomedical applications due to their high swelling potential, tailored mechanical properties, biocompatibility, and ability to incorporate drugs to modify their release behavior. This study explored the synthesis of dual stimuli-responsive composite hydrogels by combining poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) with 4, 8, and 12 % (w/w) of cellulose nanocrystals (CNC) through in-situ free-radical polymerization, modifying their properties for topical anti-inflammatory release. Although PDMAEMA-based hydrogels have been known for their responsiveness to pH and temperature stimuli, which are useful for modulating the release profile of drugs, their use as a matrix for anti-inflammatory topical applications remains unexplored. Thus, a comprehensive analysis of CNC concentration's impact on PDMAEMA-based hydrogel structure and physicochemical properties is provided. The incorporation of ibuprofen as an anti-inflammatory model was assessed, providing insights into the potential of these composite hydrogels for sustained drug delivery applications. Overall, the hydrogels exhibited homogenous CNC dispersion, with gel fraction higher than 70 % and ibuprofen load higher than 90 %. The rise in CNC concentration led to an increase hydrogel stiffness. Finally, the CNC incorporation also modified the ibuprofen release to a more sustained profile, following the Peppas-Sahlin model, which may be attractive for developing pharmaceutical devices for different therapeutical scenarios.

Preparation and Characterization of Hydrogels Fabricated From Chitosan and Poly(vinyl alcohol) for Tissue Engineering Applications.

In this study, we report on the preparation, characterization, and cytocompatibility of hydrogels for biomedical applications made from two different molecular weights of chitosan (CS) blended with poly(vinyl alcohol) (PVA) and chemically cross-linked with tetraethyl orthosilicate (TEOS) followed by freeze-drying. A series of CS-PVA hydrogels were synthesized with different amounts of chitosan (1%, 2%, and 3% by weight). The structure of these CS-PVA hydrogels was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The hydrogel samples were also characterized for tensile strength, contact angle, swelling behavior, and degradation at physiological body temperature. Their physicochemical properties, biocompatibility, and cell viability when cultured with human dermal fibroblasts were assessed using alamarBlue and live/dead assays and compared to optimize their functionality. SEM analysis showed that the concentration and molecular weight of the chitosan component affected the pore size. Furthermore, the contact angle decreased with increasing chitosan content, indicating that chitosan increased its hydrophilic properties. The in vitro degradation study revealed a nonlinear time-dependent relationship between chitosan concentration or molecular weight, and the rate of degradation was affected by the pore size of the hydrogel. All of the CS-PVA hydrogels exhibited good cell proliferation, particularly with the high molecular weight chitosan samples.

Bacterial Blocking and Repair of Intestinal Defects With Well-Alighed Lamellar MXene/Polyvinyl Alcohol Hydrogels Prepared by Bidirectional Freezing Method

To explore the bacterial blocking effect of oriented multilayer MXene/polyvinyl alcohol (PVA) nanocomposite hydrogels and their effect on the repair of intestinal defects. MXene/PVA nanocomposite hydrogels were prepared using the traditional freezing method and the bidirectional freezing ice template method. The structures of the different hydrogels were observed using scanning electron microscopy (SEM) and micro-CT reconstruction. The rheological properties of the hydrogels were measured using a dynamic rheometer, and their mechanical properties were assessed using a universal testing machine. The burst pressure of the hydrogels was determined through burst experiments, and bacterial colony growth was observed by the osmosis method to assess the bacteria blocking ability of the hydrogels in vitro. A rat model of cecal perforation was established, and the hydrogels were used for intestinal repair. Gram staining was performed to observe in vivo the bacterial blocking ability of the hydrogels, HE staining was performed to observe the intestinal inflammation, and CD31 and CD68 immunofluorescence staining and proliferating cell nuclear antigen (PCNA) staining were performed to observe the repair effect of the hydrogels on intestinal defects. SEM and micro-CT reconstruction revealed that the hydrogel prepared by the traditional freezing method exhibited a random porous structure, while the hydrogel prepared by the bidirectional freezing method showed an oriented multilayer structure. Rheological and tensile tests indicated that the oriented hydrogel had superior mechanical properties, and the burst pressure of the oriented multilayer hydrogel was as high as 27 kPa, significantly higher than that of the non-oriented hydrogel (P<0.001). Bacterial colony growth was observed by the osmosis method and it was found that, compared with the non-oriented hydrogel, the oriented multilayer hydrogel could effectively prevent the infiltration of Escherichia coli and Staphylococcus aureus in vitro. Gram staining results showed that the oriented multilayer hydrogel could effectively block intestinal bacteria from entering the abdominal cavity in vivo. HE staining results showed that the oriented multilayer hydrogel could effectively reduce intestinal inflammation in vivo. CD31 and CD68 immunofluorescence staining and PCNA staining results showed that the oriented multilayer hydrogel had a repairing effect on intestinal defects in vivo. The oriented multilayer hydrogel prepared by bidirectional freezing effectively prevents bacterial infiltration and reduces intestinal inflammation.

Acid-mediated strategies designed for stretchable and durable polyacrylamide/sodium alginate dual-network hydrogels toward flexible capacitors and wearable sensors

The utilization of acid as a synthesis assistant provides an effective means to regulate the structure of hydrogels, thereby simplifying the design and preparation process of multifunctional hydrogels. However, there remains a dearth of discourse concerning the utilization of this convenient acid-mediated strategy, which possesses the potential to directly govern molecular interactions within gel networks for rational structure and property design. Herein, we describe the preparation of flexible dual-network conductive hydrogels using polyacrylamide (PAM) and sodium alginate (SA) as substrates, driven by the strategy of acid-mediated (HCI, H2SO4, and H2C2O4) in detail for the first time. Especially, the structure-activity relationship of hydrogels was elucidated through a comparative analysis of molecular dynamics (MD) simulations and empirical properties, thereby enhancing the understanding of this field. Furthermore, extensive investigations have been conducted to explore the distinct impacts of acid ions and concentrations. The acid-mediated method exhibits superior versatility and operability compared to the filler modification method, thereby enabling a more convenient acquisition of conductive and robust hydrogels suitable for flexible capacitors and wearable sensors. Consequently, this study presents a straightforward, efficient, and cost-effective universal strategy for targeted functional hydrogel design.

Injectable immunoregulatory hydrogels sequentially drive phenotypic polarization of macrophages for infected wound healing

Regulating macrophage phenotypes to reconcile the conflict between bacterial suppression and tissue regeneration is ideal for treating infectious skin wounds. Here, an injectable immunoregulatory hydrogel (SrmE20) that sequentially drives macrophage phenotypic polarization (M0 to M1, then to M2) was constructed by integrating anti-inflammatory components and proinflammatory solvents. In vitro experiments demonstrated that the proinflammatory solvent ethanol stabilized the hydrogel structure, maintained the phenolic hydroxyl group activity, and achieved macrophages' proinflammatory transition (M0 to M1) to enhance antibacterial effects. With ethanol depletion, the hydrogel's cations and phenolic hydroxyl groups synergistically regulated macrophages' anti-inflammatory transition (M1 to M2) to initiate regeneration. In the anti-contraction full-thickness wound model with infection, this hydrogel effectively eliminated bacteria and even achieved anti-inflammatory M2 macrophage accumulation at three days post-surgery, accelerated angiogenesis and collagen deposition. By sequentially driving macrophage phenotypic polarization, this injectable immunoregulatory hydrogel will bring new guidance for the care and treatment of infected wounds.

Characterization Methods to Determine Interpenetrating Polymer Network (IPN) in Hydrogels.

Significant developments have been achieved with the invention of hydrogels. They are effective in many fields such as wastewater treatment, food, agriculture, pharmaceutical applications, and drug delivery. Although hydrogels have been used successfully in these areas, there is a need to make them better for future applications. Interpenetrating polymer networks (IPNs) can be created to make hydrogels more adjustable and suitable for a specific purpose. IPN formation is an innovative approach for polymeric systems. It brings two or more polymer networks together with entanglements. The properties of IPNs are controlled by its chemistry, crosslinking density, and morphology. Therefore, it is necessary to understand characterization methods in order to detect the formation of IPN structure and to develop the properties of hydrogels. In recent studies, IPN structure in hydrogels has been determined via chemical, physical, and mechanical methods such as Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), and rheology methods. In this paper, these characterization methods will be explained, recent studies will be scrutinized, and the effectiveness of these methods to confirm IPN formation will be evaluated.

3D printing assisted surface patterning process on acrylated hydrogels for contact guidance of fibroblasts

Generating stable and customizable topography on hydrogel surfaces with contact guidance potential is critical as it can direct/influence cell growth. This necessitates the development of new techniques for surface patterning of the hydrogels. We report on the design of a square grid template for surface patterning hydrogels. The template was 3-D printed and has the diameter of a well in a 24-well plate. Hyaluronic acid methacrylate (HA) hydrogel precursor solutions were cast on the 3D printed template's surface, which generated 3D square shape topographies on the HA hydrogel surface upon demolding. The 3D Laser Microscopy has shown the formation of a periodic array of 3D topographies on hydrogel surfaces. 3D Laser and Electron Microscopy Imaging have revealed that this new method has increased the surface area and exposed the underlying pore structure of the HA hydrogels. To demonstrate the method's versatility, we have successfully applied this technique to generate 3D topography on two more acrylate hydrogel formulations, gelatin Methacrylate and polyethylene glycol dimethacrylate. Human neonatal dermal fibroblast cells were used as a model cell line to evaluate the cell guidance potential of patterned HA hydrogel. Confocal fluorescence microscopy imaging has revealed that the 3D surface topographies on HA hydrogels can guide and align the actin filaments of the fibroblasts presumably due to the contact guidance mechanism. The newly developed methodology of 3D topography generation in acrylate hydrogels may influence the cell responses on hydrogel surfaces which can impact biomedical applications such as tissue engineering, wound healing, and disease modeling.

Gamma-Irradiated Gum Arabic Grafted with 2-Hydroxyethyl Methacrylate: A Novel Superabsorbent Polymer for Controlled Folic Acid Release.

This study explores the synthesis and characterization of superabsorbent hydrogels derived from chemically modified gum Arabic, designed for controlled folic acid release. The synthesis involves a two-step process: carboxymethylation followed by grafting with 2-hydroxyethyl methacrylate via gamma irradiation. The resulting hydrogels exhibit enhanced mechanical strength and controlled diffusivity, essential for nutrient delivery systems. Key factors such as copolymer composition and irradiation dose are investigated, affecting the synthesis process. Systematic studies of swelling behaviors reveal that the hydrogel achieves a maximum swelling of 888.1% at 40°C. The hydrogels are loaded with folic acid, and in vitro, sustained release profiles are examined under various pH conditions. The maximum release of 83.3% is observed after 24h at pH 7.0, following a Korsmeyer-Peppas release mechanism. Different characterization techniques, confirm the successful synthesis and unique properties of the superabsorbent hydrogels. Rheological behavior analysis, scanning electron microscopy, and biocompatibility assessments provide a comprehensive understanding of the hydrogel structures. Gamma irradiation ensures a homogeneous network structure, crucial for optimal swelling behavior and mechanical properties. This research highlights the potential of eco-friendly biopolymer hydrogels in precise drug delivery applications, leveraging the safety and process control benefits of gamma irradiation.

In Vitro Biological Evaluation of an Alginate-Based Hydrogel Loaded with Rifampicin for Wound Care.

We report a biocompatible hydrogel dressing based on sodium alginate-grafted poly(N-vinylcaprolactam) prepared by encapsulation of Rifampicin as an antimicrobial drug and stabilizing the matrix through the repeated freeze-thawing method. The hydrogel structure and polymer-drug compatibility were confirmed by FTIR, and a series of hydrogen-bond-based interactions between alginate and Rifampicin were identified. A concentration of 0.69% Rifampicin was found in the polymeric matrix using HPLC analysis and spectrophotometric UV-Vis methods. The hydrogel's morphology was evaluated by scanning electron microscopy, and various sizes and shapes of pores, ranging from almost spherical geometries to irregular ones, with a smooth surface of the pore walls and high interconnectivity in the presence of the drug, were identified. The hydrogels are bioadhesive, and the adhesion strength increased after Rifampicin was encapsulated into the polymeric matrix, which suggests that these compositions are suitable for wound dressings. Antimicrobial activity against S. aureus and MRSA, with an increased effect in the presence of the drug, was also found in the newly prepared hydrogels. In vitro biological evaluation demonstrated the cytocompatibility of the hydrogels and their ability to stimulate cell multiplication and mutual cell communication. The in vitro scratch assay demonstrated the drug-loaded alginate-grafted poly(N-vinylcaprolactam) hydrogel's ability to stimulate cell migration and wound closure. All of these results suggest that the prepared hydrogels can be used as antimicrobial materials for wound healing and care applications.

Graphene nanoribbon hydrogel scaffold for highly conductive and robust polyimide nanocomposite

Although highly loaded graphitic nanocarbon materials effectively enhance the electrical, mechanical, and thermal properties of polymeric materials, their practical implementation has been hindered by severe aggregation issues. Here, we propose a method to achieve homogeneous nanocarbon-polyimide (PI) composites by integrating graphene oxide nanoribbons (GONRs) with polyamic acid ammonium (PAA) salt, a precursor of PI. Self-assembled scaffold structure of GONRs hydrogel enables the uniform integration and immobilization of PAA within the GONR scaffold, mitigating aggregation concerns. The resulting GONR/PAA hydrogel, formed through physical interactions, can be coated onto substrates via a shear stress-induced bar coating method due to its viscoelastic rheological properties. Subsequent heat treatment at 400 °C triggers the imidization reaction of PAA and the reduction of GONR, facilitating the formation of uniformly integrated GNR/PI nanocomposite coatings. Under optimized conditions, incorporating a high-loading GONR content in PAA (95 wt% of GONR and 5 wt% of PAA) yielded GNR/PI composites with excellent mechanical properties, exhibiting a hardness of 0.75 GPa and an elastic modulus of 8.3 GPa. Additionally, this GNR/PI composite displayed a good electrical conductivity of 3890 S/m, attributed to the electrical pathways formed by GNRs within the PI matrix.

Mathematical modelling of genipin-bovine serum albumin interaction using fluorescence intensity measurements

The interaction between genipin and a model protein bovine serum albumin (BSA), with and without the addition of acetic acid, has been studied experimentally and by modelling. The number of amino groups available to react was determined to be 5.6 % of the total number of amino acid building blocks on BSA. Fluorescence intensity was used to record the progress of the reaction over the 24 h, while the modelling study focused on capturing the kinetic profiles of the reaction. The experiments revealed a slow start to the BSA and genipin interaction, that subsequently accelerated in an S-shaped curve which the modelling study linked with the existence of the feedback cycle for both reactive amino groups and genipin. At BSA concentrations ≥30 mg/mL the reaction was accelerated in the presence of acid, while below 30 mg/mL the acidified conditions delayed the onset of the reaction. Contrary to the reaction mechanisms previously proposed, a degree of breakdown of the fluorescent links in the products formed was denoted both experimentally and in a modelling study. This indicated the reversibility of the processes forming fluorescent product/s and suggested feasibility of the successful release of the protein following prospective encapsulation within the genipin-crosslinked hydrogel structure.

Redox-Responsive Hydrogels Loaded with an Antibacterial Peptide as Controlled Drug Delivery for Healing Infectious Wounds.

Infectious wounds occur when harmful microorganisms such as bacteria or viruses invade a wound site. Its problems associated include delayed healing, increased pain, swelling, and the potential for systemic infections. Therefore, developing new wound dressing materials with antibacterial effects is crucial for improving the healing process. Here a redox-degradable hydrogel loaded with an antibacterial peptide (vancomycin) in a straightforward gram-scale synthesis, is developed. The hydrogel structure consists of a disulfide bond-containing hyperbranched polyglycerol (SS-hPG) that is cross-linked by 4-arm polyethylene glycol-thiol (4-arm PEG-SH). The polymerization mechanism and full characterization of SS-hPG are described as this synthesis is reported for the first time. Rheology is used to ascertain the hydrogel's mechanical characteristics, such as stiffness, and self-healing, determining these properties for different ratios and concentrations of both gel components. The incorporation of disulfide bonds in the hydrogel is proved by conducting degradation experiments in reductive environments. Fluorescein isothiocyanate-albumin (FITC-BSA) and vancomycin both are loaded into the gel, and the guest release kinetics is assessed for both slow and on-demand releases. Finally, the in vitro and in vivo experiments prove that the vancomycin-loaded hydrogel acts as an antibacterial barrier for wound dressing and accelerates the healing of infectious wounds in a mouse model.

Combined extraction of manganese during water purification of technogenic solutions

A method for demanganization of technogenic aqueous solutions is presented. This method involves electrocoagulation purification of aqueous systems from high metal contents and extraction of manganese (II) ions by carbon sorbent adsorption. A coagulation technology based on electrogenerated aluminum hydroxide was used. According to diffraction analysis, such a hydroxide exhibits an amorphous porous hydrogel structure with a developed sorbing surface. The micellar structure of the as-generated aluminum hydroxide, which was attributed to a modification of gibbsite, is represented by the following colloidal particle: {[m Al(OH)3] nAl(OH)2+ (n-x) OH-}x+ xOH-. The associative process of sorption on gibbsite occurs by dispersion interaction, which is governed by the force of electrostatic attraction of instantaneous and induced dipoles of electrically neutral sorbent molecules and the [Mn (OH2)2(OH)2]0 manganese hydroxo-aquo complex. The adsorption limiting value of manganese ions amounted to 4.9 mmol/g at 298 K and pH 5.8, with the adsorption equilibrium constant reaching 1.36 . 104. The electricity consumption corresponded to 12.0 А.h at an optimal electrocoagulation duration of 15 min and a current density of 1.6 мА/сm2. The final purification of aqueous solutions using carbon sorbents was conducted in a slightly alkaline medium at pH 7.5. The manganese sorption value reached 1.68 mmol/g. Therefore, the resource-saving effect of processing of technogenic hydro-mineral solution is manifested in a significant reduction of heavy metal salts and in obtaining of demanded mixed coagulants of aluminum and iron sulfates from water purification wastes. Another positive effect of electrochemical water purification consist in water disinfection and its improved ogranoleptic parameters.

3D-Printed Hydrogels with High-Strength and Anisotropy Mediated by Chain Rigidity.

Extrusion-based 3D printing is a facile technology to construct complex structures of hydrogels, especially for tough hydrogels that have shown demonstrated potential in load-bearing materials and tissue engineering. However, 3D-printed hydrogels often possess mechanical properties that do not guarantee their usage in tissue-mimicking, load-bearing components, and motion sensors. This study proposes a novel strategy to construct high-strength and anisotropic Fe3+ cross-linked poly(acrylamide-co-acrylic acid)/sodium alginate double network hydrogels. The semi-flexible sodium alginate chains act as a "conformation regulator" to promote the formation of strong intermolecular interactions between polymer chains and lock the more extended conformation exerted by the pre-stretch, enabling the construction of 3D-printed hydrogel structures with high orientation. The equilibrated anisotropic hydrogel filaments with a water content of 50-60 wt.% exhibit outstanding mechanical properties (tensile strength: 9-44MPa; elongation at break: 120-668%; Young's modulus: 7-62MPa; toughness: 26-52MJm- 3). 3D-printed anisotropic hydrogel structures with high mechanical performance show demonstrated potential as loading-bearing structures and electrodes of flexible triboelectric nanogenerators for versatile human motion sensing.