Alginate Hydrogel Fibers Research Articles

Continuous dual-network alginate hydrogel fibers with superior mechanical and electrical performance for flexible multi-functional sensors

Hydrogel fibers play a crucial role in the design and manufacturing of flexible electronic devices. However, continuous production of hydrogel fibers with high strength, toughness, and conductivity remains a significant challenge. In this study, ion-conductive sodium alginate/polyvinyl alcohol composite hydrogel fibers with an interlocked dual network structure were prepared through continuous wet spinning based on the pH-responsive dynamic borate ester bonds. Owing to the interlocked dual network structure, the resulting hydrogel fibers integrated superior performance of strength (4.31 MPa), elongation-at-break (>1500 %), ion conductivity (17.98 S m−1) and response sensitivity to strain (GF = 3.051). Benefiting from the excellent performance, the composite hydrogel fiber could be applied as motion-detecting sensors, including high-frequency, high-speed reciprocating mechanical motion, and human motion. Furthermore, the superior compatibility for human-computer interaction of the hydrogel fiber was also demonstrated, which a manipulator could be controlled to perform different actions, by a smart glove equipped with the hydrogel fiber sensors.

Synthesis and characterization of natural fibers reinforced alginate hydrogel fibers loaded with diclofenac sodium for wound dressings

Hydrogels which become increasingly important in the biomedical field are composed of a three-dimensional hydrophilic network. Pure hydrogels are usually weak and brittle; therefore, reinforcements are assimilated into the hydrogel structure to improve the mechanical strength of the hydrogels. However, even if mechanical properties are enhanced, drapability remains an issue. In that regard, natural fiber-reinforced composite hydrogel fibers for wound dressing application are investigated in this study. Kapok and hemp fibers were used as reinforcement to improve the strength of hydrogel fibers. The properties of the prepared composite hydrogel fibers were studied with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimeter (DSC). The effect of alginate concentration and fiber weight percent on the mechanical characteristics and water absorbency was studied. Diclofenac sodium drug was loaded in the hydrogel fibers and investigated the drug release as well as antibacterial characteristics. Both fibers' reinforcement enhanced the strength of the alginate hydrogel fiber, but hemp reinforcement showed better mechanical properties. Kapok reinforcement resulted in a maximum tensile strength of 174 cN (1.24 % elongation) and 432 % exudate absorbency, while hemp reinforcement resulted in 185 cN (1.48 % elongation) and 435 % exudate absorbency. Statistical analysis revealed significant effects of sodium alginate concentration on tensile strength (p-value 0.042) and exudate absorbency (p-value 0.020) and of reinforcement (wt%) on exudate absorbency (p-value 0.043). Therefore, these composite hydrogel fibers with improved mechanical properties are capable of drug release and exhibit antibacterial effectiveness, making them a promising option for use as wound dressings.

Preparation of Wide-Domain pH Color-Changing Nanocapsules and Application in Hydrogel Fibers.

In recent years, there has been an increase in demand for pH color-changing materials. These materials can visually communicate signals to people by connecting pH changes with color information. Embedding pH indicators into fibers to create flexible color-changing materials is an effective way to develop daily wearable products. For the stability of the indicator and the indirect contact of the indicator with the human body, it is usually necessary to encapsulate it in capsules. In this study, different pH indicators (Thymol Blue-TB, Bromocresol Green-BCG, and Bromocresol Purple-BCP) were mixed into a wide-domain pH color-changing indicator and encapsulated with ethyl cellulose (EC) by the flash nanoprecipitation (FNP) method using a new-type droplet-shaped confined impinging jet mixer. The effects of flow rate, core-to-wall ratio, and mixed solution concentration on the formation of the nanocapsules were investigated. In addition, the morphology, particle size, size distribution, dispersion stability, and encapsulation efficiency were systematically studied. At a core-to-wall ratio of 1:2, a mixed solution with a concentration of 6 mg/mL and a feed flow rate of 40 mL/min produced nanocapsules with an average particle size of 141.83 ± 0.98 nm and a PDI of 0.125 ± 0.01. Furthermore, a zeta potential with a range of -31.83 ± 0.23 mV and an encapsulation efficiency of 75.20 ± 1.72% were observed at 1:2 core-to-wall ratios. It was concluded that the color of the nanocapsules continuously changed from yellow to green and green to blue when the pH range was increased from 3 to 10. The color-changing nanocapsules were then embedded into sodium alginate hydrogel fibers, resulting in the same color-changing trend (pH 3-10) as that obtained for the nanocapsules. This study can be useful for the pH monitoring of various body fluids, such as wound exudate, urine, and sweat.

Preparation and Characterization of Alginate Hydrogel Fibers Reinforced by Cotton for Biomedical Applications.

In this study, cotton-reinforced alginate hydrogel fibers were successfully synthesized using the wet spinning technique to improve hydrogel fibers' mechanical strength and durability. Structural, chemical, and mechanical properties of the prepared fibers were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray Diffraction, differential scanning calorimeter, and single fiber strength tester. Based on the results obtained from fourier transform infrared spectroscopy and x-ray Diffraction, cotton fibers have been successfully incorporated into the structure of the hydrogel fibers. It was seen from the differential scanning calorimeter results that the incorporation of fibers in the structure even enhanced the thermal stability of the fiber and is viable to be implanted in the human body. Cotton reinforcement in alginate hydrogel fibers increases the modulus up to 56.45 MPa providing significant stiffness and toughness for the hydrogel composite fiber. The tenacity of the fibers increased by increasing the concentration of alginate from 2.1 cN/Tex (1% w/v) to 8.16 cN/Tex (1.5% w/v). Fiber strength increased by 26.75% and water absorbance increased by 120% by incorporating (10% w/w) cotton fibers into the fibrous structure. It was concluded that these cotton-reinforced alginate hydrogel fibers have improved mechanical properties and liquid absorption properties suitable for use in various biomedical applications.

Electrochemical Glue for Binding Chitosan–Alginate Hydrogel Fibers for Cell Culture

Three-dimensional organs and tissues can be constructed using hydrogels as support matrices for cells. For the assembly of these gels, chemical and physical reactions that induce gluing should be induced locally in target areas without causing cell damage. Herein, we present a novel electrochemical strategy for gluing hydrogel fibers. In this strategy, a microelectrode electrochemically generated HClO or Ca2+, and these chemicals were used to crosslink chitosan–alginate fibers fabricated using interfacial polyelectrolyte complexation. Further, human umbilical vein endothelial cells were incorporated into the fibers, and two such fibers were glued together to construct “+”-shaped hydrogels. After gluing, the hydrogels were embedded in Matrigel and cultured for several days. The cells spread and proliferated along the fibers, indicating that the electrochemical glue was not toxic toward the cells. This is the first report on the use of electrochemical glue for the assembly of hydrogel pieces containing cells. Based on our results, the electrochemical gluing method has promising applications in tissue engineering and the development of organs on a chip.

Mechanical Stabilization of Alginate Hydrogel Fiber and 3D Constructs by Mussel-Inspired Catechol Modification.

Alginate is a representative biocompatible natural polymer with low cost for a variety of biomedical applications, such as wound dressing, drug delivery systems, tissue scaffolds, and 3D bioprinting. Particularly, the rapid and facile gelation of alginate via ionic interactions with divalent cations has been used for in situ 3D hydrogel fiber formation, which is potentially applicable to engineering cell alignment. However, challenges in enhancing the mechanical properties of alginate hydrogel fibers under physiological conditions are unresolved because of their fast dissociation by ion exchange. Herein, we report a stabilization strategy for alginate hydrogel fibers through mussel-inspired catechol chemistry, which involves inter-catechol crosslinking within a few minutes under basic conditions. The fabrication of catechol-tethered alginate hydrogel fibers through wet-spinning enabled the design of mechanically strong 3D constructs consisting of fibers. Catechol-to-quinone oxidation followed by covalent crosslinking enhanced the tensile strength of a single fiber. Additionally, the ‘gluing’ capability of the catechol stabilized the interface among the fibers, thus retaining the shape fidelity of the 3D constructs and encapsulating the cell density during culture. Our findings will be useful for designing bioink materials specialized in fibrous-type tissue scaffolds with mechanical stability.

Graphene Oxide/Alginate Hydrogel Fibers with Hierarchically Arranged Helical Structures for Soft Actuator Application

Hierarchically arranged helical structures were constructed in graphene oxide (GO)/alginate hydrogel fibers by combining the wet spinning and confined drying methods. After fixing both ends of the ...

Biological properties of sulfanilamide-loaded alginate hydrogel fibers based on ionic and chemical crosslinking for wound dressings

In this work, alginate hydrogel fibers loading sulfanilamide were proposed using a combination of Ca2+ ions and glutaraldehyde crosslinking to develop an efficient wound dressing. The structure, mechanical properties, absorbency, in vitro drug release and cytotoxicity of the proposed alginate hydrogel fibers were investigated systematically. The results indicated that crosslinking with glutaraldehyde can efficiently enhance the mechanical properties of the alginate hydrogel fibers, and reduce their swelling degree which is beneficial for hydrogel fibers to obtain adjustable fluid adsorption capacity, sustained drug release feature over hydrogel fibers crosslinked only by Ca2+ ions. Antibacterial activity assay demonstrated the bactericidal ability of the alginate hydrogel fibers towards S. aureus and E. coli with the highest antibacterial rate of 99.9%. Furthermore, a preliminary trial of papermaking process for producing alginate hydrogel mats showed the workability and the applicability of the mechanically tough hydrogel fibers. Cytotoxicity assay indicated the enhancement of cell adhesion and proliferation, revealing the non-cytotoxicity and biocompatibility of the alginate hydrogel mats. Based on the excellent mechanical strength, adjustable fluid adsorption capacity, sustained drug release, and biocompatibility, the bi-crosslinked alginate hydrogel fibers had a promising application as ideal wound dressings in clinic.

A coaxially extruded heterogeneous core-shell fiber with Schwann cells and neural stem cells.

Cellular therapies play a critical role in the treatment of spinal cord injury (SCI). Compared with cell-seeded conduits, fully cellular grafts have more similarities with autografts, and thus might result in better regeneration effects. In this study, we fabricated Schwann cell (SC)-neural stem cell (NSC) core–shell alginate hydrogel fibers in a coaxial extrusion manner. The rat SC line RSC96 and mouse NSC line NE-4C were used in this experiment. Fully cellular components were achieved in the core portion and the relative spatial positions of these two cells partially mimic the construction of nerve fibers in vivo. SCs were demonstrated to express more genes of neurotrophic factors in alginate shell. Enhanced proliferation and differentiation tendency of NSCs was observed when they were co-cultured with SCs. This model has strong potential for application in SCI repair.

Alginate/gelatin blended hydrogel fibers cross-linked by Ca2+ and oxidized starch: Preparation and properties

Alginate/gelatin blended hydrogel fibers were successfully prepared based on sodium alginate cross-linked by Ca2+ and gelatin cross-linked by oxidized starch through the wet spinning process. The structure, surface morphologies, swelling properties of alginate hydrogel fibers and alginate/gelatin blended hydrogel fibers were examined by Fourier transform infrared analysis (FTIR), cross-linking degree test, element analysis test and scanning electron microscopy (SEM). While mechanical properties test, water absorption and retention properties test provide the mechanical, water absorption and retention properties. FTIR, cross-linking degree and element analysis results indicate that there is gelatin remaining in alginate/gelatin blended hydrogel fibers. However, the cross-linking of gelatin by oxidized starch is not completed with some dissociative gelatin solvated in the coagulation bath. Among the mentioned fibers, FS10G2 is the best to improve the properties of alginate/gelatin blended hydrogel fibers with an optimal mass ratio of sodium and gelatin. The excessive additive amount of gelatin leads to the aggregation of gelatin in alginate/gelatin blended hydrogel fibers, making the worse compatibility between alginate and gelatin. It also destroys the mechanical properties of alginate/gelatin blended hydrogel fibers. These alginate/gelatin blended hydrogel fibers might have a potential application in the biomedical fields.

CELL LADEN ALGINATE/ALBUMIN HYDROGEL FIBERS FOR POTENTIAL SKIN TISSUE ENGINEERING APPLICATIONS

Alginate hydrogel fibers are receiving a great attention for tissue engineering applications. However, an important limitation of alginate is that it does not provide cell adhesion motifs. In this work, albumin was blended with alginate to improve the compatibility of alginate fibers with cells. Cell laden alginate/albumin fibers, potentially usable for skin regeneration, were obtained through a spinning process, by extruding an alginate/albumin solution containing cells into a calcium chloride solution. Cell laden pure alginate fibers were prepared for comparison. Plain alginate and alginate/albumin fibers were also produced. Morphological, mechanical and functional properties of the produced fibers were investigated. In addition, the ability of the fibers to release albumin and to support the viability and growth of A549 cells embedded into them was studied. Fibers with a uniform shape and an average diameter within the range 550–570[Formula: see text][Formula: see text]m were produced. The water content was [Formula: see text]% for alginate fibers, and [Formula: see text]% for alginate/albumin fibers. Stress–strain tests showed, up to a strain value of 20%, the same Young’s modulus for the produced fibers, regardless of the presence of albumin. Overall, obtained results demonstrated that morphology, size, hydrophilicity and mechanical properties were not affected by albumin. Albumin was gradually released over a period of 4 days, with a residual amount (13%) remaining into the fibers. Viability test was carried out on A549 cells, laden inside alginate and alginate/albumin fibers, to evaluate cell proliferation ability. A favorable effect of albumin on the loaded cells was evidenced by a faster kinetics of growth.

Microfluidic fabrication of highly stretchable and fast electro-responsive graphene oxide/polyacrylamide/alginate hydrogel fibers

The practical application of electro-responsive hydrogels is limited due to the slow response rate and the poor mechanical property. The electro-response rate of hydrogels can be improved by forming hydrogel fiber and adding graphene oxide (GO). Meanwhile, the incorporation of GO can also enhance the mechanical properties of hydrogels. However, the highly stretchable and fast electro-responsive hydrogel fibers are rarely reported at present. In this paper, graphene oxide/polyacrylamide/sodium alginate hydrogel fibers were prepared by microfluidic spinning and free radical polymerization. The mechanical properties, swelling properties and electro-responsive behaviors of the nanocomposite hydrogel fibers were investigated. The results show the nanocomposite hydrogel fibers could be very stretchable by adjusting GO and N,N-methylenebisacrylamide (BIS) contents. Besides, compared with hydrogel rods, the hydrogel fibers with diameter in microscale exhibit much faster swelling rate and electro-response rate. The thinner the hydrogel fiber is, the faster the electro-response rate is. This suggests that the highly stretchable and fast electro-responsive hydrogel fibers take us closer to the application of artificial muscle actuators.

Three‐dimensional plotted alginate fibers embedded with diclofenac and bone cells coated with chitosan for bone regeneration during inflammation

Alginate hydrogel fibers embedded with bone cells and diclofenac were coated with a layer of chitosan hydrogel and made into a porous scaffold by three-dimensional (3D) printing for drug release and bone regeneration. It was hypothesized that the chitosan coating could improve the scaffold's drug retention and release properties and biocompatibility. Macrophage cells were stimulated and cocultured with the scaffold. Tests were conducted to show how the chitosan coating affected the scaffold's drug release efficacy and how the release efficacy affected the cellular activities of stimulated macrophages and bone cells. The bone cells encapsulated in the coated scaffold demonstrated good viability after the acidic/basic coating process. The coating improved the retention and release efficacy of diclofenac and hence significantly inhibited interleukin-6 and tumor necrosis factor-α secretion from macrophages (p < 0.05). The bone cells in the coated sample mineralized more extensively than the control (p < 0.01). They also more actively expressed genes that produce proteins for extracellular matrix remodeling, MMP13, and interacting with the mineral matrix, OPN (both p < 0.01). It is believed that on days 7 and 10, when diclofenac was depleted and the concentrations of inflammatory compounds surged, the coating effectively blocked the harmful compounds and protected the bone cells within the fibers. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1511-1521, 2018.

Mechanical Reinforcement of Low‐Concentration Alginate Fibers by Microfluidic Embedding of Multiple Cores

AbstractThis paper presents mechanically reinforced low‐concentration alginate fibers by embedding inner cores of high‐concentration alginate. 3D structures by stacking multiple polydimethylsiloxane (PDMS) layers allow the microfluidic formation and control of the isolated cores in the continuous flow. The alginate hydrogel fibers are simply spun, and the compartments, central core, surrounding cores, and outer shell layer are successfully verified. The results demonstrate the great potential for the development of complex fibrous materials, particularly for biological applications, which require specific morphology and composition of the fibers.

Fabrication of a microchannel using chain-shaped alginate hydrogel fibers as sacrificial structure

In this research, we proposed a method to fabricate a PDMS chain-shaped microchannel by using a chain-shaped alginate hydrogel fiber as sacrificial structure. Embedding and dissolving a chain-shaped alginate hydrogel fiber in a PDMS structure, we succeeded in formation of a chain-shaped microchannel. When we infused 2 different colors of ink into this microchannel from 2 inlets, we achieved the control of flow regimes between laminar and vibrated flows according to their flow rates. Therefore, we believe that the chain-shaped alginate hydrogel fiber will be a useful tool for a simple and low-cost preparation of PDMS microchannels with complex shapes.

Development of zirconia nanoparticles-decorated calcium alginate hydrogel fibers for extraction of organophosphorous pesticides from water and juice samples: Facile synthesis and application with elimination of matrix effects

In this research, novel zirconia nanoparticles-decorated calcium alginate hydrogel fibers (ZNCAHF) were synthesized through a simple, green procedure. ZNCAHF were used as an adsorbent in the micro–solid-phase extraction (MSPE) of methyl parathion (MP), fenitrothion (FT) and malathion (MT) as model pesticides prior to gas chromatography-mass spectroscopic detection (GC–MS). The composition and morphology of the prepared fiber were characterized by Fourier transform-infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray diffraction (EDX), and differential scanning calorimetry (DSC). Various parameters affecting fabrication of the fiber (weight ratio of components) and relative extraction recovery (pH, amount of adsorbent, extraction time, salt addition, and desorption conditions) were investigated and optimized. Under optimized conditions, the calibration curves were obtained in the concentration range of 0.01–500ngmL−1 with regression coefficients between 0.9997 and 0.9999. The limits of detection (LOD) (S/N=3) and limits of quantification (LOQ) (S/N=10) of the method ranged from 0.001 to 0.004ngmL−1 and 0.003 to 0.012ngmL−1, respectively. The intra-day and inter-day relative standard deviations (RSDs) were 2.2–5.9% and 3.2–7.8%, respectively. The applicability of the fabricated adsorbent was investigated by extraction of selected organophosphorous pesticides (OPPs) from real samples of juice and water. The obtained relative recoveries were in the range of 90.6-105.4%, demonstrating elimination of matrix effects which can be attributed to the remarkable affinity of OPPs toward ZNCAHF.

Chitosan-coated alginate tissue scaffold constructed by three-dimensional plotting technique used for drug and cell delivery

Event Abstract Back to Event Chitosan-coated alginate tissue scaffold constructed by three-dimensional plotting technique used for drug and cell delivery Hsin-Yi Lin1 and Tsang-Wen Chang1 1 National Taipei University of Technology, Chemical Engineering and Biotechnology, Taiwan Introduction: It’s essential that the hydrogel carrier systems for drug and cell delivery be made in mild conditions quickly enough to prevent excessive loss of the drugs and cells they carry. Alginate solution can quickly form hydrogel in the presence calcium ions but the hydrogel is highly hydrophilic and degrades quickly in the presence of monovalent ions. Chitosan hydrogel is more hydrophobic and degrades more slowly compared to alginate. However, harmful chemicals are used in the process of making chitosan hydrogel and prevent chitosan from being used to encapsulate living cells. The two materials were combined to make a better cell/drug delivery tissue scaffold. Alginate hydrogel fibers containing bone cells and diclofenac, an anti-inflammatory drug, were constructed into 3D scaffolds and coated with a layer of chitosan hydrogel. We hypothesized that the alginate hydrogel could shield the embedded cells from the acid/base used during the chitosan coating processes. The chitosan coating was then expected to better preserve diclofenac during the scaffold making and to slow down diclofenac release during cell culture. Materials and Methods: The scaffolds were constructed by the three-dimensional (3D) plotting apparatus. In brief, an alginate solution containing osteoblasts and diclofenac was extruded into a calcium chloride+ chitosan acetic acid solution. The alginate formed hydrogel fibers with a thin layer of chitosan coating. The fibers were built layer by layer into a 3D scaffold and quickly neutralized in NaOH before rinsing (saline, pH=7). The cell/diclofenac-containing alginate scaffolds coated with chitosan (A/C) were co-cultured with macrophage cells in a-MEM containing lipopolysaccharide (LPS). LPS stimulates macrophages to release inflammatory species that are harmful to the cells. Diclofenac was known to inhibit macrophage cells from producing the inflammatory species. The cells and drug in 3D-printed plain alginate scaffolds (A) were used as control. The drug loading and release efficacies and the performance of the cells in the scaffolds were examined. Results and Discussion: A layer of chitosan was successfully coated onto the alginate hydrogel fibers of the tissue scaffold built. Chitosan fluoresced green (Ex=488nm) and the coating could be distinguished using scanning electron microscopy (Fig1). Also the cells embedded in A/C were viable after the chitosan-coating process. The chitosan coating was able to slow down the release of diclofenac from the alginate hydrogel. More diclofenac remained in A/C than in A after the post-processing steps were completed (Fig2). A/C carried more diclofenac and released it in a more sustainable fashion than A. As a result the concentrations of inflammatory species from macrophages co-cultured with A/C were significantly lower than those from macrophages co-cultured with A. Osteoblasts embedded in A/C hence grew faster, had higher alkaline phosphatase activity and mineralized more extensively (Fig2). Conclusion: A better cell/drug-containing tissue scaffold was developed by coating a layer of chitosan on the fibers of a 3D plotted alginate scaffold that contained diclofenac and cells. The cells inside the alginate hydrogel survived the harmful chemicals during chitosan coating and the coating then significantly enhanced the scaffold’s drug loading and release efficacies. Ministry of Science and Technology grand: MOST-2221-E-027-095 Keywords: Tissue Engineering, Drug delivery, 3D scaffold, Bone repair Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Biomaterials in constructing tissue substitutes Citation: Lin H and Chang T (2016). Chitosan-coated alginate tissue scaffold constructed by three-dimensional plotting technique used for drug and cell delivery. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01752 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Hsin-Yi Lin Tsang-Wen Chang Google Hsin-Yi Lin Tsang-Wen Chang Google Scholar Hsin-Yi Lin Tsang-Wen Chang PubMed Hsin-Yi Lin Tsang-Wen Chang Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Fibrous hydrogel scaffolds with cells embedded in the fibers as a potential tissue scaffold for skin repair

A novel approach was undertaken to create a potential skin wound dressing. L929 fibroblast cells and alginate solution were simultaneously dispensed into a calcium chloride solution using a three-dimensional plotting system to manufacture a fibrous alginate scaffold with interconnected pores. These cells were then embedded in the alginate hydrogel fibers of the scaffold. A conventional scaffold with cells directly seeded on the fiber surface was used as a control. The encapsulated fibroblasts made using the co-dispensing method distributed homogeneously within the scaffold and showed the delayed formation of large cell aggregates compared to the control. The cells embedded in the hydrogel fibers also deposited more type I collagen in the extracellular matrix and expressed higher levels of fgf11 and fn1 than the control, indicating increased cellular proliferation and attachment. The results indicate that the novel co-dispensing alginate scaffold may promote skin regeneration better than the conventional directly-seeded scaffold.

Gelatin blends with alginate: Gel fibers for α-galactosidase immobilization and its application in reduction of non-digestible oligosaccharides in soymilk

α-Galactosidase from Aspergillus oryzae was physically entrapped in gelatin blended alginate hydrogel fibers hardened with glutaraldehyde. Immobilization yield resulted in 71.75%. The optimum conditions were not affected by immobilization, and the optimum pH and temperature for free and immobilized enzyme were 4.8 and 50 °C, respectively. Immobilized α-galactosidase was more stable at higher pH and temperature. To improve the immobilization system polyols like glycerol (C 3) was used with different amounts of Na-alginate and gelatin. The free α-galactosidase activity quickly decreased and the half time of the activity decay was about 5 days at 4 °C. The immobilized enzyme remained very active over a long period of time and this enzyme lost about 70% of its original activity over the period of 60 days for storage at 4 °C. Immobilized α-galactosidase was used in batch, repeated batch and continuous mode to degrade the non-digestible oligosaccharides present in soymilk. The performance of immobilized α-galactosidase was also tested in a fluidized bed reactor at different flow rates and 93% reduction of NDO in soymilk was obtained at 25 ml h −1 flow rate. The study revealed that alginate–gelatin fiber entrapped α-galactosidase shows the higher immobilization yield, greater storage stability and better percent hydrolysis of NDO present in soymilk compared to alginate and gelatin entrapped α-galactosidase.