Hydrogel Concentration Research Articles

Hydroentangled waste cotton non-woven based alginate hydrogel wound dressing for high wound exudates

Hydrogels are used in modern wound dressings due to their ability to provide comfort with quick healing. However, poor mechanical properties of hydrogels limit their availability in commercial wound dressings. Nonwovens are highly porous, strong, and flexible structures that can provide support to hydrogels without compromising their properties. In this study, a cost-effective and sustainable hydroentangled nonwoven from industrial cotton waste was prepared and incorporated into alginate hydrogel for wound dressings. The novel composite of hydroentangled cotton nonwoven and alginate hydrogel was synthesized by a simple sol-gel technique. The effect of concentration of alginate hydrogel (0.5 wt%, 1 wt%, 1.5 wt %) and drying temperature (20 °C, 40 °C, 60 °C) of composite was analyzed for high wound exudates. The properties of prepared composite samples were characterized by scanning electron microscopy (SEM), XRD, tensile strength, tear strength, Air permeability, moisture management wound exudate test, and quantitative antimicrobial testing. Moreover, the comfort performance of these samples was evaluated by air permeability and moisture management testing. The properties of developed composites are highly dependent on the concentration of alginate and drying temperature. The results showed that maximum fluid absorbency (%) of 650 was achieved with good comfort properties. This study can help to increase the commercial availability of hydrogel-based wound dressings.

Biomimetic fiber/hydrogel composite scaffolds based on chitosan hydrogel and surface modified PCL chopped-microfibers

Hydrogel/fiber composites have received wide attention as tissue engineering scaffolds due to the outstanding properties of fibers and hydrogels. In the current research, a hydrogel/fiber composite scaffold was made based on chitosan-modified polycaprolactone (PCL) microfibers and chitosan hydrogel as a binder. The presence of chitosan as a modifier on the surface of fibers and as a binder between fibers can create scaffolds with excellent structural and mechanical properties. To this end, the three-dimensional microfibers were first functionalized with amine groups. Then, the chitosan chains were attached to the fibers by an aldehyde coupling agent and Schiff base reaction. FTIR and Raman spectroscopies corroborated that chitosan was successfully immobilized on PCL fibers. Chitosan-modified fibers were molded with chitosan solutions of various concentrations and the prepared composite scaffolds were stabilized using ionic crosslinking. The obtained composites represented a porous 3D structure with highly interconnected pores. The compressive modulus increased by 19 and 2.7 folds and the tensile modulus was augmented by 28 and 4 folds, in respective dry and swollen states with increasing hydrogel concentration from 0.1 to 1 %. Hydrogel/fiber composites were able to preserve cell viability, and increasing the hydrogel proportion increased adhesion, proliferation and penetration of cells into the scaffold.

Инновационные продукты питания с заменителями насыщенных жиров

Purpose. Development of plant oil-based bigels using sodium alginate hydrogel and beeswax-based oleogel, selection of the optimal ratio between the concentration of hydrogel and oleogel in the composition of bigel, study of its thermal and textural characteristics. Materials and Мethods. Effect of hydrogel-to-oleogel ratio on bigel production was evaluated in terms of thermal and structural-mechanical properties. The following recipe ingredients: drinking water, sodium alginate, beeswax, grape seed oil, were used to produce bigels. Results. It was found that increasing proportion of hydrogel had influenced on thermal properties, strength and adhesiveness of the bigels. In general, an increase hydrogel fraction made it possible to obtain bigels with stronger mechanical properties and higher heat resistance, which is important to consider when creating technologies for innovative food products. Conclusion. For developing various food products with substitution of saturated fats with food bi-gel matrices, it is necessary to regulate competently their physicochemical and textural properties.

Experimental studies on controlling dispersion and fluid flow in paper membranes/assays using hydrogel

Paper membranes find applications in various fields, including Point-of-Care (POC) diagnostics, separation, filtration, and fluid transport. Still, they are frequently plagued by dispersion-related issues that lead to uneven flow, further affecting sensitivity and specificity, especially in detection assays. Hence, flow control in paper membranes becomes essential to achieving an effective paper-based platform. The present work develops a novel methodology based on adaptive flow regulation to optimize dispersion and flow control. This approach leverages real-time data to measure the controlled flow rates and prevent dispersion using hydrogel across paper-based membranes. Effects of three major parameters, namely mixing speed (100 rpm – 400 rpm), hydrogel concentration (6.45 mg/ml–12.9 mg/ml) for preparing hydrogel, and types of filter paper membranes are investigated in detail. Imaging techniques are applied to capture high-resolution images of fluid behavior on the paper strip surface at various time intervals, and the results are demonstrated in terms of mean intensity as a quantifiable indicator (0−255). It was found that the hydrogel prepared using 400 rpm mixing speed at a specific concentration exhibited significant resistance to the fluid flow with minimal dispersion. Furthermore, the Filter-paper 441 membrane is compared with other filter-paper membranes used in this experiment. Notably, a 43 %-79 % reduction in dispersion was observed for the hydrogel-laden paper membranes. Additionally, the dispersion was largely minimized even when lower concentrations of sodium hydroxide were detected on hydrogel-based paper assays, enhancing its sensitivity. Overall, this research offers a multifaceted solution to reduce dispersion and optimize flow control in paper-based membranes using hydrogel to improve the performance of the paper assays.

Bone Morphogenetic Protein 7-Loaded Gelatin Methacrylate/Oxidized Sodium Alginate/Nano-Hydroxyapatite Composite Hydrogel for Bone Tissue Engineering.

Bone tissue engineering (BTE) is a promising alternative to autologous bone grafting for the clinical treatment of bone defects, and inorganic/organic composite hydrogels as BTE scaffolds are a hot spot in current research. The construction of nano-hydroxyapatite/gelatin methacrylate/oxidized sodium alginate (nHAP/GelMA/OSA), abbreviated as HGO, composite hydrogels loaded with bone morphogenetic protein 7 (BMP7) will provide a suitable 3D microenvironment to promote cell aggregation, proliferation, and differentiation, thus facilitating bone repair and regeneration. Dually-crosslinked hydrogels were fabricated by combining GelMA and OSA, while HGO hydrogels were formulated by incorporating varying amounts of nHAP. The hydrogels were physically and chemically characterized followed by the assessment of their biocompatibility. BMP7-HGO (BHGO) hydrogels were fabricated by incorporating suitable concentrations of BMP7 into HGO hydrogels. The osteogenic potential of BHGO hydrogels was then validated through in vitro experiments and using rat femoral defect models. The addition of nHAP significantly improved the physical properties of the hydrogel, and the composite hydrogel with 10% nHAP demonstrated the best overall performance among all groups. The selected concentration of HGO hydrogel served as a carrier for BMP7 loading and was evaluated for its osteogenic potential both in vivo and in vitro. The BHGO hydrogel demonstrated superior in vitro osteogenic induction and in vivo potential for repairing bone tissue compared to the outcomes observed in the blank control, BMP7, and HGO groups. Using hydrogel containing 10% HGO appears promising for bone tissue engineering scaffolds, especially when loaded with BMP7 to boost its osteogenic potential. However, further investigation is needed to optimize the GelMA, OSA, and nHAP ratios, along with the BMP7 concentration, to maximize the osteogenic potential.

Autoclaving Achieves pH-Neutralization, Hydrogelation, and Sterilization of Chitosan Hydrogels in One Step

Conventionally, chitosan hydrogels are acidic and contain toxic chemicals because chitosan is soluble only in acidic solvents and requires toxic additives such as chemical crosslinkers and polymerization agents to fabricate chitosan hydrogels. These properties prevent chitosan hydrogels from being used for medical applications. In this study, chitosan hydrogels were prepared by a simple and versatile process using urea hydrolysis by autoclaving (steam sterilization, 121 °C, 20 min). When autoclaved, urea hydrolyzes in an acidic chitosan aqueous solution, and ammonia is produced, which increases the pH of the solution, and chitosan becomes insoluble, leading to the formation of a chitosan hydrogel. The pH and osmotic concentration of chitosan hydrogels could be adjusted to be suitable for physiological conditions (pH: 7.0–7.5, and osmotic concentration: 276–329 mOsm/L) by changing the amount of urea added to chitosan solutions (chitosan: 2.5% (w/v), urea: 0.75–1.0% (w/v), pH: 5.5). The hydrogels had extremely low cytotoxicity without the washing process. In addition, not only pure chitosan hydrogels, but also chitosan derivative hydrogels were prepared using this method. The autoclaving technique for preparing low-toxic and wash-free sterilized chitosan hydrogels in a single step is practical for medical applications.

A biodegradable alginate/chitosan hydrogel based nonwoven from pre-consumer cotton waste and virgin wool for food packaging

The municipal waste is polluting the environment by releasing harmful substances. There is a demand for eco-friendly food packaging with higher shelf life. In this study, a biodegradable nonwoven for food packaging was developed using cotton waste and alginate/chitosan hydrogel. Firstly, needle-punched nonwovens were prepared from two different kinds of cotton waste (comber noil and card-fly) and wool fibers. The prepared nonwovens were immersed in a solution of alginate/chitosan followed by cross-linking with sodium chloride which resulted in formation of layers of hydrogel on/into nonwovens. The developed nonwovens for food packaging were characterized by using FTIR, DSC, SEM, air permeability and water absorbency tests. Moreover, mechanical strength and antibacterial evaluation of prepared nonwovens was also done. The properties of developed packaging materials are dependent on fiber type and concentration of hydrogel. The water absorption rate is highest (1 sec to 25 sec) in the case of wool fiber-based hydrogel nonwoven with tensile strength ranging from 65 N to 90 N. Moreover, all the developed samples of nonwoven alginate/chitosan hydrogel showed good antibacterials and air barrier (360 mm/sec to 620 mm/sec properties). The results indicate that the nonwoven alginate/chitosan hydrogel holds significant promise as an environmentally friendly substitute for food packaging materials.

3D bioartificial stretchable scaffolds mimicking the mechanical hallmarks of human cardiac fibrotic tissue.

Human cardiac fibrotic tissues are characterized by a higher stiffness relative to healthy cardiac tissues. These tissues are unable to spontaneously contract and are subjected to passive mechanical stimulation during heart functionality. Moreover, scaffolds that can recapitulate the in vivo mechanical properties of the cardiac fibrotic tissues are lacking. Herein, this study aimed to design and fabricate mechanically stretchable bioartificial scaffolds with biomimetic composition and stiffness comparable to human cardiac fibrotic tissues. Poly(ε-caprolactone) (PCL) scaffolds with a stretchable mesh architecture were initially designed through structural and finite element method (FEM) analyses and subsequently fabricated by melt extrusion additive manufacturing (MEX). Scaffolds were surface functionalized by 3,4-dihydroxy-DL-phenylalanine (DOPA) polymerization (polyDOPA) to improve their interaction with natural polymers. Scaffold pores were then filled with different concentrations (5%, 7%, and 10% w/v) of gelatin methacryloyl (GelMA) hydrogels to support in vitro human cardiac fibroblasts (HCFs) 3D culture, thereby producing bioartificial PCL/GelMA scaffolds. Uniaxial tensile mechanical tests in static and dynamic conditions (1 Hz; 22% maximum strain) demonstrated that the bioartificial scaffolds had in vivo-like stretchability and similar stiffness to that of pathological cardiac tissue (tailored as a function of the number of PCL scaffold layers and GelMA hydrogel concentration). In vitro cell tests on bioartificial scaffolds using HCF-embedded GelMA hydrogels under static conditions displayed increasing cell viability, spreading, and cytoskeleton organization with decreasing GelMA hydrogel concentration. Moreover, α-smooth muscle actin (α-SMA)-positive cells were detected after 7 days of culture in static conditions followed by another 7 days of culture in dynamic conditions and not in HCF-loaded scaffolds cultured in static conditions for 14 days. These results suggested that in vitro culture under cyclic mechanical stimulations could induce an HCF phenotypic switch into myofibroblasts.

The crystallization properties of antifreeze GelMA hydrogel and its application in cryopreservation of tissue-engineered skin constructs.

Gelatin methacrylate (GelMA) hydrogels are expected to be ideal skin tissue engineering dressings for a wide range of clinical treatments. Herein, we report the preparation of GelMA or antifreeze GelMA hydrogel sheets with different GelMA concentrations, crosslinking times, and cryoprotectant (CPA) concentrations. The crystallization properties of GelMA or antifreeze GelMA hydrogel sheets were studied by cryomicroscopy and differential scanning calorimetry (DSC). It was found that the growth of ice crystals was slower when GelMA hydrogel concentration was more than 7%. The 10% DMSO-7% GelMA hydrogel sheets crosslinked for 60 min showed no ice crystal formation and growth during cooling and warming. The DSC results showed that the vitrification temperature of the 10% DMSO-7% GelMA hydrogel sheet was -111°C. Furthermore, slow freezing and rapid freezing of fibroblast-laden GelMA or antifreeze GelMA hydrogel sheets, and tissue-engineered skin constructs were studied. The results showed no significant difference in cell survival between slow (88.8% ± 1.51) and rapid (89.2% ± 3.00) freezing of fibroblast-loaded 10% DMSO-7% GelMA hydrogel sheets, and significantly higher than that of 7% GelMA hydrogel sheets (33.4% ± 5.46). The cell viability was higher in tissue-engineered skin constructs after slow freezing (86.34% ± 1.45) than rapid freezing (72.74% ± 1.34). We believe that the combination of antifreeze hydrogels and tissue engineering will facilitate the cryopreservation of tissue engineering constructs.

Magnetic, Biocompatible and Biodegradable Carboxymethyl Cellulose‐Based Hydrogel for Cationic Dye Adsorption

AbstractEnsuring the availability of water resources that are both clean and safe is crucial for the preservation of environmental health and the well‐being of humans. Here, we fabricated carboxymethyl cellulose‐based hydrogel nanocomposite using acrylic acid (AA) and 2‐acrylamido‐2‐methylpropane sulfuric acid (AMPS) monomers and Fe3O4 nanoparticles through a free radical crosslinking process for adsorption of dyes from contaminated water. The synthesized nanocomposite hydrogel was characterized using various techniques, including TEM, XRD, FTIR, SEM‐EDS, TGA, and AFM analysis. The swelling capacity of samples in an aqueous medium at multiple pH levels and the presence of different salts were investigated. The adsorption efficiency of methylene blue (MB) and crystal violet (CV), emphasizing the effect of hydrogel concentration and the medium's pH, was studied. It was concluded that the hydrogel sample containing 17 % AMPS and 51 % AA had better swelling capacity and dye removal efficiency. The dye adsorption kinetics data were fitted to pseudo‐first and second‐order kinetic models and the Langmuir and Temkin isotherm models. The maximum adsorption capacity for MB and CV was 53.97 and 53.57 mg/g, respectively. It was revealed that the pseudo‐second‐order kinetic model could best describe adsorption (qe=79.2 mg/g for MB and qe=65.8 mg/g for CV). The intra‐particle diffusion model was found to be the rate‐limiting mechanism of dye adsorption. Thermodynamic studies proposed that the adsorption of MB and CV was spontaneous and endothermic. Additionally, magnetic nanocomposite hydrogel‘s reusability up to four successive cycles further determines its probability of adsorption of dyes from wastewater.

The Thermophysical Aspects of the Transformation of Porous Structures in Versatile Nanostructured Materials

The technology of obtaining porous nanostructures is based on ecological organosilicon materials and their uses in some spheres of human life, for example, for medical preparations, for thermal insulation of building structures and industrial equipment, and for cleaning. The purpose of this study was to establish correlations between various experimental parameters (shear stress, speed pulsations, temperature, viscosity, and processing time) and the rheological characteristics of suspensions obtained by the method of liquid-phase dispersion; it was a study of hydrodynamic effects and the processes of heat and mass exchange in liquid systems during the liquid-phase dispersion of hydrogel monoliths by means of discrete-pulse activation in a special rotary apparatus. The dehydration of hydrogels was carried out by two methods: convective drying in a layer and spraying in the coolant flow. Experiments have shown that the key parameters for obtaining stable homogeneous suspensions are a synergistic combination of concentration factors and processing time. To obtain adsorbents in the form of pastes with specified adsorption properties and a monolith size of up to 300 μm, the optimal parameters were a hydrogel concentration of 70% and a processing time in the double-recirculation mode. Xerogels obtained by convective drying are a polydisperse mixture of strong monoliths and fragile aggregates. In contrast, xerogel monoliths obtained by spray drying show great homogeneity in terms of dispersion and strength characteristics. The rheological parameters of the hydrogel dispersions, which depend on the concentration and hydrodynamic treatment modes, are the dominant factors affecting the moisture extraction during drying. This study marks the first investigation into the resilience of porous organosilicon structures against the influence of intense turbulence fields and mechanical stresses experienced within the rotor apparatus during suspension production.

Investigation of swelling behaviour monolayer and double Layer polysaccharide based composite hydrogels

ABSTRACT In this study, monolayer and double layer (core-shell) composite hydrogel beads with and without hydroxyapatite which have potential applications in drug delivery systems were synthesized, and their swelling behaviours were investigated in different pH mediums. The composite hydrogel beads was prepared by crosslinking sodium alginate and kappa-carrageenan (by using Ca+2 and K+1). Core-shell hydrogel beads were formed by coating monolayer composite hydrogel beads with the mixture of sodium alginate and kappa-carrageenan. The structure of hydrogel beads was characterized by Fourier Transform Infrared Spectrophotometer, Scanning Electron Microscopy and Differential Scanning Calorimetry. The effects of the composite hydrogel beads combination and the concentration of crosslinker on swelling behaviours were investigated. Swelling kinetics data were tested using pseudo-second-order model, and the pseudo-second-order model is estimated as a convenient model to represent the swelling kinetic. The results indicated that swelling behaviours of hydrogel beads changed with composite hydrogel beads combination and concentration of crosslinker.

Investigation of the early apical release from endodontic hydrogels: A 3D printed model.

Regenerative Endodontic Procedures (REPs) using new materials such as hydrogels aim to replace current endodontic treatments, but numerous limitations are to overcome. Apical release was little explored in previous studies, especially regarding hydrogels that incorporate molecules, such as growth factors and antibiotics. Apical release is a key mechanism in achieving regeneration, as it could regulate disinfection or cell colonization. Few models exist for apical release, limiting the transfer of these devices from bench to bedside. This study aims to design a simple and standardized model to identify parameters that influence the early apical release kinetic of molecules from endodontic hydrogels. Endodontic Release Inserts (ERI) were designed to mimic the situation of an immature incisor using three different diameters (Ø 0.5 to 2 mm) and to allow the study of the early release from a hydrogel in a 96-well plate. ERI was produced with a 3D printing machine. The kinetic release was investigated using 2 fluorescent, hydrophobic (BDP-500) and hydrophilic (Fluorescein) molecules, in different hydrogels (fibrin and agarose) and in various media (PBS or serum). The release kinetics were estimated by measuring the fluorescence at different time points (1 to 24 h). ERI use made it possible to report that apical diameters increase from 500 to 1000 μm was associated with an increase in release from 4.02 ± 1.63% to 11.53 ± 2.38% over 24 h. It also allowed us to report that bottom solution composition change from PBS to human serum was associated with an increase in the release of fatty acid molecules, whilst a decrease in the hydrogel concentration was associated with a variation in release kinetics. Moreover, nano-encapsulation of a molecule was associated with a decreased release over the first 24 h from 5.25 to 0%. ERI use enables investigation of the parameters influencing release kinetics from endodontic hydrogels. Further investigations are necessary to evaluate the interaction of these parameters with each other, in animal models and clinic.

Development of Novel Cornstarch Hydrogel-Based Food Coolant and its Characterization.

The food, pharmaceutical, and supply transport storage chain is seeking coolants that come with plastic-free packaging, are nontoxic, environmentally friendly, robust, reusable, and reduce water waste. To meet this demand, a new food coolant based on cornstarch hydrogel was developed and tested using the regeneration method. This study investigated the reusability, water retention, rehydration, and surface cleanliness of the hydrogel, along with its application in freshness retention for fruits. The results of the gel strength and differential scanning calorimetry (DSC) analysis showed that the ideal concentration of cornstarch hydrogel was 8%. Freezing and thawing experiments demonstrated that the hydrogel had the potential to be used as a cooling medium for refrigerated fresh foods. Moreover, the gel strength, scanning electron microscopy images (SEM), DSC, and thermogravimetric analysis (TG) revealed that the freeze-thaw reuse only slightly affected its freezable water content and that its gel strength gradually increased during reuse. Water retention and rehydration tests showed that the hydrogels could be better preserved at -20 °C compared to 4 °C, and the water lost during reuse could be replenished through rehydration. The flexibility in terms of shape and size also allows the hydrogel ice to be used as a customized coolant for various food shapes, as demonstrated by preservation experiments. Additionally, washing the hydrogel after each use can result in a significant reduction in Escherichia coli, Salmonella, and Staphylococcus aureus concentrations by 3.03, 3.47, and 2.77 log CFU/hydrogel, respectively. Overall, the new cornstarch hydrogel coolant is a promising alternative to conventional ice, with the potential to serve as a food coolant.

Functionality of macrophages encapsulated in porcine decellularized adipose matrix hydrogels and interaction with Candida albicans

Extracellular matrix hydrogels are considered one of the most suitable biomaterials for tissue regeneration due to their similarity with the extracellular microenvironment of the native tissue. Their properties are dependent on their composition, material concentration, fiber density and the fabrication approaches, among other factors. The encapsulation of immune cells in this kind of hydrogels, both in absence or presence of a pathogen, represents a promising strategy for the development of platforms that mimic healthy and infected tissues, respectively. In this work, we have encapsulated macrophages in 3D hydrogels of porcine decellularized adipose matrices (pDAMs) without and with the Candida albicans fungus, as 3D experimental models to study the macrophage immunocompetence in a closer situation to the physiological conditions and to mimic an infection scenario. Our results indicate that encapsulated macrophages preserve their functionality within these pDAM hydrogels and phagocytose live pathogens. In addition, their behavior is influenced by the hydrogel pore size, inversely related to the hydrogel concentration. Thus, larger pore size promotes the polarization of macrophages towards M2 phenotype along the time and enhances their phagocytosis capability. It is important to point out that encapsulated macrophages in absence of pathogen showed an M2 phenotype, but macrophages coencapsulated with C. albicans can switch towards an M1 inflammatory phenotype to resolve the infection, depending on the fungus quantity. The present study reveals that pDAM hydrogels preserve the macrophage plasticity, demonstrating their relevance as new models for macrophage-pathogen interaction studies that mimic an infection scenario with application in regenerative medicine research.

Contact-line bending energy controls phospholipid vesicle adhesion

Phospholipid bilayer bending energy is often discarded in the analysis of vesicle adhesion on the basis of a dimensionless parameter w = − Δ U R 0 2 / κ b ≫ 1 (interaction energy Δ U , spherical radius R 0 , bending rigidity κ b ), considered a regime of strong adhesion. In this study, we propose a model by which bending energy in a singular proximity of the contact line balances the adhesion energy. This is developed for a regime in which the membrane correlation length ξ is small compared with the vesicle radius R 0 , so a spherical cap with circular footprint presents an effective contact angle θ . Experiments are conducted in which the adhesion of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) vesicles to hyaluronic acid hydrogel substrates is controlled by tuning the van der Waals attraction with systematic change in the hydrogel concentration. Theoretical interpretation of the data furnishes a dimensionless model parameter α ≈ 2 – 10 for contact angles θ ≈ 20 – 80 ∘ , beyond which vesicles collapse into discs. We show that the van der Waals interaction energy varies in the range − Δ U ≈ 0.14 – 0.68 μ J m − 2 in response to varying the hydrogel concentration in a range c ha ≈ 2 – 10 %. The analysis provides a foundation for exploring vesicle–hydrogel interactions with electro-steric influences; these are poorly understood but pertinent in a wide variety of biological and technological applications.

Enhancing Bone Cement Efficacy with Hydrogel Beads Synthesized by Droplet Microfluidics

Effective filling materials, typically bone cements, are essential for providing mechanical support during bone fracture treatment. A current challenge with bone cement lies in achieving continuous drug release and forming porous structures that facilitate cell migration and enhance osteoconductivity. We report a droplet microfluidics-based method for synthesizing uniform-sized gelatin hydrogel beads. A high hydrogel concentration and increased crosslinking levels were found to enhance drug loading as well as release performance. Consequently, the droplet microfluidic device was optimized in its design and fabrication to enable the stable generation of uniform-sized droplets from high-viscosity gelatin solutions. The size of the generated beads can be selectively controlled from 50 to 300 μm, featuring a high antibiotic loading capacity of up to 43% dry weight. They achieve continuous drug release lasting more than 300 h, ensuring sustained microbial inhibition with minimal cytotoxicity. Furthermore, the hydrogel beads are well suited for integration with calcium phosphate cement, maintaining structural integrity to form porous matrices and improve continuous drug release performance. The uniform size distribution of the beads, achieved through droplet microfluidic synthesis, ensures predictable drug release dynamics and a measurable impact on the mechanical properties of bone cements, positioning this technology as a promising enhancement to bone cement materials.

Sawdust-derived cellulose nanofibrils with high biosafety for potential bioprinting

Cellulose is a sustainable biopolymer with potential to reduce the adverse environmental impact of non-biodegradable plastics and promote a circular economy. Nanocellulose, a representative biobased nanomaterial, is considered as a promising material in biomedical applications due to its outstanding biocompatibility and low toxicity. However, the presence of some leachable immunogenic contaminants, such as endotoxin and (1,3)-β-D-glucan, in nanocellulose will often pose a potential risk in biomedical applications, particularly to the human body in 3D printing. In line with this challenge, a novel nanocellulose fabricating method was innovatively developed from the source of sawdust biomass to minimize the possible immunogenic contaminants presented in the cellulose nanofibrils (CNFs), which will ensure its biocompatibility of the material in applications. The resulting CNFs exhibited a very low level of leachable contaminants, recorded with endotoxin at 1.39 EU/g and (1,3)-β-D-glucan at 2.82 μg/g, respectively, which fall within the acceptable levels of Pharmacopoeia. In the following evaluation with the fabricated CNFs, the printability of the CNF hydrogel scaffolds was further optimized with hydrogel concentration at 5 %, printing pressure at 37 kPa, nozzle size setting up at 25 G, and crosslinker concentration at 200 mM, respectively. As an important property of 3D printed hydrogel scaffold, its biocompatibility was further evaluated and observed through cell culture in vitro, where the extract of hydrogel scaffold demonstrated a 36 % higher cell viability in promoting cell growth and proliferation when compared with that in pure culture medium. This exploration would suggest a possible application in the biomedical field that may not only secure a sound biocompatibility of CNFs produced from sawdust biomass, but also ensure the following 3D-printed scaffold with a viable cell growth and proliferation.

Self-assembled and perfusable microvasculature-on-chip for modeling leukocyte trafficking.

Leukocyte recruitment from blood to tissue is a process that occurs at the level of capillary vessels during both physiological and pathological conditions. This process is also relevant for evaluating novel adoptive cell therapies, in which the trafficking of therapeutic cells such as chimeric antigen receptor (CAR)-T cells throughout the capillaries of solid tumors is important. Local variations in blood flow, mural cell concentration, and tissue stiffness contribute to the regulation of capillary vascular permeability and leukocyte trafficking throughout the capillary microvasculature. We developed a platform to mimic a biologically functional human arteriole-venule microcirculation system consisting of pericytes (PCs) and arterial and venous primary endothelial cells (ECs) embedded within a hydrogel, which self-assembles into a perfusable, heterogeneous microvasculature. Our device shows a preferential association of PCs with arterial ECs that drives the flow-dependent formation of microvasculature networks. We show that PCs stimulate basement membrane matrix synthesis, which affects both vessel diameter and permeability in a manner correlating with the ratio of ECs to PCs. Moreover, we demonstrate that hydrogel concentration can affect capillary morphology but has no observed effect on vascular permeability. The biological function of our capillary network was demonstrated using an inflammation model, where significantly higher expression of cytokines, chemokines, and adhesion molecules was observed after tumor necrosis factor-alpha (TNF-α) treatment. Accordingly, T cell adherence and transendothelial migration were significantly increased in the immune-activated state. Taken together, our platform allows the generation of a perfusable microvasculature that recapitulates the structure and function of an in vivo capillary bed that can be used as a model for developing potential immunotherapies.

A multifunctional cellulose- and starch-based composite hydrogel with iron-modified biochar particles for enhancing microalgae growth

A multifunctional polysaccharide-based hydrogel was studied as an additive for enhancing microalgae growth. The hydrogel was fabricated by physically and chemically crosslinking renewable ingredients of carboxymethyl cellulose (CMC), arrowroot starch, and activated biochar modified with iron using a bio-crosslinker of oxidized sucrose and a plasticizer of glycerol. The optimum formula for the hydrogel with a high swelling ratio, BET surface area, and electrical conductivity was found to include 1 g starch, 3 g CMC, 1.5 g biochar, 15 mL oxidized sucrose, and 1.5 mL glycerol in 200 mL deionized water. The algal yield and cell concentration after 14 days of growth in a Bold basal medium with an optimum concentration of 2.5 g hydrogel/L increased by 65.7 % and 92.2 %, respectively, compared to those of the control without the hydrogel. However, if the hydrogel concentration in the culture increased to 12.5 g/L, the algal yield was decreased by 67.8 % compared to the control due to oxidative injury. The hydrogel additive could significantly increase the nitrogen but decrease the carbon, hydrogen, and sulfur contents of the microalgae. The algal yield with 2.5 g/L hydrogel additive improved by 13.9 % compared to the algal yield with the same amounts of individual non–crosslinked hydrogel ingredients.