Internal Gelation Method Research Articles

Structural and thermo-physical properties of sol-gel derived yttria stabilized zirconia microspheres: A viable inert matrix for minor actinide incineration

To embark upon the challenges in the field of nuclear industry including proliferation and waste management, the utilization of U-free fuel matrix (Inert Matrix Fuel) are proposed to be utilized to burn and transmute various minor actinides including Pu, Am etc. Thus in this direction, yttria stabilized zirconia (YSZ) microsphere matrix co-doped with different mol% of Ce and Nd were synthesized using internal gelation method. Different metal concentrations [M] and hexamthylnetetramine+urea (HMTA-urea) concentrations ([HMTA-urea]/[M]= [R]) were used in order to prepare crack free YSZ microspheres. The conventional sol gel method used led to the formation of anisotropic tetragonal phase due to the leaching of constituent elements. Thus a modified scheme was developed as elaborated in detail in the manuscript which resulted into an isotropic cubic phase for all compositions. The thermo-physical properties like thermal expansion, heat capacity and thermal conductivity of the samples were evaluated in the temperature range 298–1473 K and are at par with the values reported for other matrices. The thermal conductivity data showed that the conduction in these materials mainly occurs through phonon conduction and the presence of enhanced oxygen vacancies in them due to Ce and Nd doping, diminishes the thermal conductivity significantly. Further, the local structure was probed using EXAFS which confirmed them to be homogenous and coordination number 8 for all the samples. Thus with the development of such kind of fuels, the risk of proliferation can be avoided with additional advantage of energy generation.

Innovative method for producing plant-based meat analogs: Acid/calcium-induced internal gelation of potato protein/alginate composites

When creating plant-based meat analogs, it is often challenging to mimic the structural and textural attributes of real meat products during the cooking process. In this study, we investigated the potential of using potato protein/calcium alginate composite gels to formulate plant-based meat analogs. These gels provide a semi-solid texture at ambient temperature that remains intact during cooking because the electrostatic crosslinks are resistant to heat. Composite gels consisting of potato protein (10 wt%) and alginate (0–2 wt%) were prepared using the internal gelation method. This method involves dispersing an insoluble form of calcium (CaHPO4) throughout the protein-polysaccharide matrix and then using glucono-delta-lactone (GDL) to slowly lower the pH, thereby releasing the Ca2+ ions evenly throughout the system. The calcium alginate increased the strength of the potato protein gels and provided structural resistance to heat. Appreciable water loss occurred during cooking for simple calcium alginate gels, but this was prevented when potato proteins were present. Increasing the alginate concentration from 0 to 1.5 % increased the strength of the composite gels but higher levels promoted phase separation and network disruption, which reduced the gel strength. Heating did not appreciably alter the microstructure of the composite gels, but it did alter that of the pure potato protein gels. Finally, the potential of the composite gels as plant-based meat analogs was assessed by comparing their thermal denaturation and textural properties to those of real chicken breast. The potato protein/alginate composites were shown to simulate the thermal denaturation and textural changes of real chicken during the cooking process. Overall, our results suggest that calcium alginate gels may be useful in the formulation of plant-based meat products with improved cooking properties.

Survivability and behavior of probiotic bacteria encapsulated by internal gelation in non-dairy matrix and In Vitro GIT conditions.

The primary objective of this investigation was to assess the viability of free and encapsulated Lactobacillus plantarum probiotics in mango juice and under simulated gastrointestinal conditions. Specifically, the probiotics were encapsulated using sodium alginate and alginate-soy protein isolate through the internal gelation method, and the obtained probiotics were characterized for various attributes. Both free and encapsulated probiotics were exposed to challenging conditions, including thermal stress, low temperature, and simulated gastrointestinal conditions. Additionally, both types of probiotics were incorporated into mango juice, and their survival was monitored over a 28-day storage period. Following viability under simulated gastrointestinal conditions, the count of free and encapsulated probiotic cells decreased from initial levels of 9.57 log CFU/mL, 9.55 log CFU/mL, and 9.53 log CFU/mL, 9.56 log CFU/mL to final levels of 6.14 log CFU/mL, 8.31 log CFU/mL, and 6.24 log CFU/mL, 8.62 log CFU/mL, respectively. Notably, encapsulated probiotics exhibited a decrease of 1.24 log CFU and 0.94 log CFU, while free cells experienced a reduction of 3.43 log CFU and 6.24 log CFU in mango juice over the storage period. Encapsulated probiotics demonstrated higher viability in mango juice compared to free probiotics throughout the 28-day storage period. These findings suggest that mango juice can be enriched with probiotics to create a health-promoting beverage.

Electrolytic Reduction of UO2 Microspheres Synthesized Via Internal Gelation Method

Pyroprocessing is the combination of process steps to extract and recycle actinides from fission products in spent nuclear fuels in high-temperature molten salt media. Pyroprocessing has been studied extensively over the past decades. One of the key sub-processes is the electrolytic reduction of uranium oxides. The electrolytic reduction process originated from the FFC Cambridge process, an approach for electrochemically reducing titanium dioxide into titanium metal in molten CaCl2. In the electrolytic reduction of uranium oxides, the uranium oxide feed is applied as the cathode in LiCl-Li2O molten salt electrolyte at 650°C. LiCl appears more promising than conventional CaCl2 owing to the lower melting point (878 K), and higher decomposition voltage (3.46 V at 923 K). Additionally, Li2O is expected to speed up the reduction via an additional chemical reduction pathway with the participation of Li metal, and prevents the direct dissolution of the Pt anode.This work aims to study the morphology effect of the oxide feed on the reduction kinetics and the incorporation of impurities during the electrolytic reduction process. The electrolytic reduction of UO2 is carried out on sintered UO2 pellets, as well as various UO2 microspheres synthesized via internal gelation. The introduction of uranium oxide microspheres holds several advantages. The spheres provide a higher surface area, which is expected to improve the overall reduction efficiency of uranium oxide during electrolysis. In addition, it is easier to handle the feed during loading and unloading of the cathode basket compared to powder feeds.The potentiostatic and galvanostatic electrolysis of UO2 is performed, and the comparison between the electrolytic reduction of UO2 pellets and microspheres is investigated. The SEM micrographs in figure 1show the morphology change of a UO2 pellet to uranium metals particles. A significant morphology change between the flat surface of the sintered UO2 feed and the reduced U particles is observed at the surface. Further characterization is performed using XRD and TGA to identify the products of the electrolytic reduction process qualitatively and quantitatively. Results show that galvanostatic electrolysis shows a better reduction efficiency compared to potentiostatic electrolysis, applied both below and above the Li formation onset potential. Overall, there is barely un-reacted UO2 visible in the XRD patterns of the reduced feed after galvanostatic electrolysis. U metal and UO are identified in the XRD patterns depending on electrolysis parameters. The presence of UO can be as an intermediate of UO2 reduction during electrolysis, which is a rare compound to be reported in literature. Overall, the reduction of microspheres does improve the overall reduction efficiency compared to the conventional pellet feeds. Figure 1

Double Network Physical Crosslinked Hydrogel for Healing Skin Wounds: New Formulation Based on Polysaccharides and Zn2.

Developing convenient, efficient, and natural wound dressings remain the foremost strategy for treating skin wounds. Thus, we innovatively combined the semi-dissolved acidified sol-gel conversion method with the internal gelation method to fabricate SA (sodium alginate)/CS (chitosan)/Zn2+ physically cross-linked double network hydrogel and named it SA/CS/Zn2+ PDH. The characterization results demonstrated that increased Zn2+ content led to hydrogels with improved physical and chemical properties, such as rheology, water retention, and swelling capacity. Moreover, the hydrogels exhibited favorable antibacterial properties and biocompatibility. Notably, the establishment of an in vitro pro-healing wound model further confirmed that the hydrogel had a superior ability to repair wounds and promote skin regeneration. In future, as a natural biomaterial with antimicrobial properties, it has the potential to promote wound healing.

Effect of internal and external gelation on the physical properties, water distribution, and lycopene encapsulation properties of alginate-based emulsion gels

It is challenging to incorporate lycopene, a strongly hydrophobic nutraceutical, into functional foods because of its low water-solubility and poor bioaccessibility. In this study, we therefore examined the potential of alginate-based emulsion gels to encapsulate and deliver lycopene. Alginate can be gelled using either internal or external gelation mechanisms, but few studies have compared the advantages and disadvantages of these two approaches for producing emulsion gels. For this reason, we compared the structure, water distribution, water mobility, and simulated digestion of lycopene-loaded emulsion gels formed by gelling alginate within the aqueous phase using either the internal or external methods. The internal gelation method produced emulsion gels that contained smaller oil droplets, and had a higher hardness, water holding capacity, and freeze-thaw stability. Moreover, the internal gelation method led to emulsion gels that had a slightly higher lycopene bioaccessibility (36.1%) than the ones formed by the external gelation method (33.4%). These findings are important for optimizing the design and fabrication of emulsion gels suitable as delivery systems for nutraceuticals in the food industry.

Preparation of Chromium doped uranium nitride via Sol-Gel and Carbothermic reduction

Uranium nitride (UN) has been proposed as an accident tolerant fuel due to its enhanced thermal properties compared to the standard UO2. However, due to its low oxidation resistance, its implementation in water cooled reactors has not been allowed. A method to improve the corrosion resistance involves doping with oxide scale forming elements such as aluminum or chromium. In this work, UN microspheres were produced by an internal gelation method followed by carbothermic reduction and nitridation. Chromium was added as dopant in the solution to produce a homogenous mixture with uranium. The ternary phase (U2CrN3) was observed for the first time in Cr-doped UN microspheres produced via sol-gel and carbothermic reduction. Materials with and without the ternary phase were produced, and a mechanism of reaction was proposed.Chromium precipitations were also observed on the surface of the microspheres produced, indicating low solubility of Cr compounds in the UN matrix. ICP-MS and XRF measurements showed that Cr content is reduced after heating treatments, probably due to evaporation. Additionally, these results showed that Cr in the ternary phase is completely soluble in aqua regia, unlike the Cr in the material without the ternary phase.

Comparison of hydrogel- and xerogel-based sorbent from Empty Fruit Bunch (EFB)

This paper focuses on the synthesis and comparison of hydrogel- and xerogel-based sorbents from EFB.Hydrogels were synthesised by polymerisation of EFB biochar with acrylamide (AAm) as a monomer, N, N'-Methylenebisacrylamide (MBA) as cross-linker and ammonium persulfate (APS) as initiator, as well as by internal gelation method of sodium alginate, empty fruit bunch (EFB), calcium carbonate (CaCO3), and glucono delta-lactone (GDL). From the alginate hydrogels obtained, xerogels were synthesised via the oven-drying method. Then, EFB-based hydrogel and xerogel sorbents were analysed and compared based on characterisation analysis by using scanning electron microscopy (SEM), BrunauerEmmettTeller (BET), Fourier-Transform Infrared Spectroscopy (FTIR), and thermogravimetric analysis (TGA).The xerogel-based EFB is a better adsorbent than the hydrogel-based EFB because it has a larger pore volume (0.001449 cm3/g), larger pore size (63.7987 nm), higher moisture content (7.97%), lower ash content (12.55%), and is more thermally stable.The research is to compare two new adsorbents, namely Hydrogel and Xerogel, from EFB in terms of their characteristics.Both adsorbents show a highly toxic material uptake, especially EFB xerogel. This adsorbent is comparable with the other commercialised adsorbent. Thus, this product can be a highly potential adsorbent for gas and wastewater adsorption.The authenticity results of this article were found to be 15% similar. The novelty of this paper is to compare the two adsorbents, namely hydrogel and xerogel, that originated from EFB.

Biomineralization-Inspired Intermediate Precursor for the Controllable Gelation of Polyphenol-Macromolecule Hydrogels.

Hydrogels composed of polyphenols and various macromolecules have been widely reported to have the advantage of facile preparation, mainly through the formation of hydrogen bonds. However, the traditional preparation method involves the direct mixing of polyphenols and macromolecules, which generally occurs too quickly and uncontrollably, and results in poor homogeneity, injectability, and shape designability. Here, inspired by the intermediate precursor during biomineralization, to facilitate transformation in a controllable way, we propose a novel and universal internal gelation method that creates an intermediate precursor by controlling the pH value to manipulate the elimination and generation of hydrogen bonds between a polyphenol and macromolecules. The precursor strategy greatly improves the homogeneity, injectability, and shape designability of the hydrogel while also achieving a controllable gelation process, and the gelation time can be accurately adjusted. The hydrogels prepared with this method exhibited superior capability to seal leaks, provided complete wound coverage, and showed the potential to be a shape-designable wearable strain sensor. Our study opens up a new way to construct and apply polyphenol-macromolecule hydrogels in a more controllable manner.

Synthesis of calcium, copper and iron alginate hydrogels doped with Ag nanoparticles produced by chemical reduction method

Calcium, copper and iron alginate hydrogels were synthesized at room temperature via using the internal gelation method from sodium alginate precursor. Also, Ag nanoparticles which were produced with chemical reduction method, were added to hydrogels with different ratios (1%, 5% and 10%) to examine the different ratio effect on hydrogel properties, especially for antibacterial behaviors. According to this experimental design, the dopant ratio efficiency of Ag nanoparticles and comparison of divalent crosslinking metal ions (Ca2+, Cu2+, Fe2+) on antibacterial properties of produced hydrogels were compared. SEM-EDS analyze was done to observe Ag nanoparticles. Both SEM and UV–Vis analyzes showed that particle size of produced Ag were ∼10 nm. The chemical structures of each hydrogel were observed with FTIR studies. After structural properties of hydrogels and Ag nanoparticles examinations, antibacterial behaviors were observed with Escherichia coli and Staphylococcus aureus environments. The results showed that 10 wt% Nano-Ag doped copper alginate against Escherichia coli and 10 wt% Nano-Ag doped copper alginate against Staphylococcus aureus showed the highest antibacterial properties.

High effective proteinaceous α-amylase inhibitors from grains and control release

Plant-derived α-amylase inhibitors exhibit great capacity in glycaemic control by restraining dietary starch digestion. However, natural α-amylase inhibitors with strong inhibitory activity and good stability are still scarce. In this study, the inhibitory activity and stability of proteinaceous α-amylase inhibitors derived from eleven grains were examined, and microencapsulation was carried out to protect the inhibitors in gastric fluid. We found that the highland barley protein extract (HBPE) showed the most potent α-amylase inhibitory activity (IC50 = 1.11 mg/mL). HBPE is a reversible noncompetitive α-amylase inhibitor and displayed good stability across various pH and temperatures. It showed high trypsin tolerance but low pepsin tolerance. Thus HBPE-encapsulated microspheres were prepared by the composite of sodium alginate/gellan gum with the internal ionic gelation method. The optimum encapsulation condition was determined, and the prepared microspheres displayed discrete, uniform and regular sphericities with diameters around 53 μm, and better mechanical strength with more than 81% activity retention rate. Moreover, the microspheres protected the HBPE in gastric fluid and extended HBPE release in the small intestinal fluid, revealing excellent control release of HBPE in simulated gastrointestinal digestion. Our study provides a new and effective strategy for the management of postprandial blood glucose.

Effect of Al2O3 on the Process Performance of ZrO2 Microspheres

Al2O3-ZrO2 microspheres were prepared by internal gelation method. The effects of Al3+ on the stability of solution and performance of gel spheres were studied. Al3+ had a great influence on the stability of the solutions, and the more of the amount of Al3+, the shorter of the stabilization time. Because Al3+ did not copolymerize with Zr4+ during the sol-gel transformation, the strength of gel sphere added with Al3+ was low and deformed easily as it was squeezed. The results of our experiments well verify Glasser team’s speculation and conclusions. At the same time, based on the experimental results, we prepared Al2O3-ZrO2 composite microspheres with higher content of Al2O3 by controlling the pH of the solution. The change curve of viscosity with time and the stabilization time of the solution with different Al3+ dosage were given, which could provide references for industrial mass production. Samples without hydrothermal treatment cracked severely, while the samples hydrothermally treated kept structural integrity with no cracks after calcined. Al2O3-ZrO2 microspheres with no segregation and phase separation were prepared and alumina evenly distributed in the zirconia matrix. When the content of Al2O3 was low, the tetragonal phase was stable. And the cubic phase was obtained when the content of Al2O3 was more.

Encapsulation of Bifidobacterium bifidum by internal gelation method to access the viability in cheddar cheese and under simulated gastrointestinal conditions.

The current study was conducted to elucidate the impact of encapsulation on the stability and viability of probiotic bacteria (Bifidobacterium bifidum) in cheddar cheese and in vitro gastrointestinal conditions. Purposely, probiotics were encapsulated in two hydrogel materials (kepa carrageenan and sodium alginate) by using an internal gelation method. Cheddar cheese was supplemented with unencapsulated/free and encapsulated probiotics. The product was subjected to physicochemical (pH, titrable acidity, moisture, and protein) and microbiological analysis for a period of 35 days of storage. Furthermore, the probiotics (free and encapsulated) were subjected to simulated gastrointestinal conditions. The initial probiotic count in cheese containing encapsulated probiotic was 9.13 log CFU/g and 9.15 log CFU/g which decreased to 8.10 log CFU/g and 7.67 log CFU/g while cheese containing unencapsulated probiotic initially 9.18 log CFU/g decreased to 6.58 log CFU/g over a period of 35 days of storage. The incorporation of unencapsulated and encapsulated probiotic affected the physicochemical, microbiological, and sensory attributes of the cheese. The encapsulated probiotic bacteria exhibited better survival as compared to unencapsulated probiotic. A 2.60 CFU/g log reduction in unencapsulated cells while just 1.03 CFU/g and 1.48 CFU/g log reduction in case of sodium alginate and K‐carrageenan, respectively, was recorded. In short, encapsulation showed protection and stability to probiotic in hostile conditions.

Construction of physically crosslinked chitosan/sodium alginate/calcium ion double-network hydrogel and its application to heavy metal ions removal

Abstract Chemical hydrogels have been extensively applied to the removal of heavy metal pollutants. However, most of chemical hydrogels inevitably contain toxic chemical crosslinker residues, which impose serious threats on the environment. Herein, a novel eco-friendly physically-crosslinked double-network hydrogel of chitosan/sodium alginate/calcium ion (CTS/SA/Ca2+ PCDNH) was prepared by the combination of the semi-dissolution acidification sol–gel transition method with the internal gelation method. The PCDNH is formed via the physical crosslinking of sustainable biopolymers, which avoids the excessive use of toxic chemical reagents. In addition, the PCDNH exhibits significantly better mechanical properties than the single-network physical hydrogel crosslinked via electrostatic interactions, which overcomes the weak mechanical properties of physical hydrogels. The formation mechanism and structure of the hydrogel were determined by Fourier-transform infrared spectroscopy (FTIR), 13C solid state nuclear magnetic resonance spectroscopy (13C-SSNMR) and scanning electron microscopy (SEM). The heavy metal ions adsorption mechanism was explored by X-ray photoelectron spectroscopy (XPS) analysis. The adsorption kinetics, isotherms and thermodynamics were further studied to understand the adsorption mechanism. Our work has provided a new method for the fabrication of natural polymers-based eco-friendly, low-cost and robust physical hydrogels for the heavy metal ions removal.

Survival and stability of free and encapsulated probiotic bacteria under simulated gastrointestinal conditions and in pasteurized grape juice

The present study was designed to explicate the effect of encapsulation on the stability of Bifidobacterium bifidum in pasteurized grape juice and in vitro gastrointestinal conditions. Purposely, hydrogel beads were prepared using sodium alginate and K-carrageenan by internal gelation method. Free and encapsulated probiotics were incorporated in pasteurized grape juice samples. The initial count in grape juice samples with free probiotic cells was calculated as 9.35 log cfu/mL that reduced to 6.58 log cfu/mL after 35 days. Likewise, the probiotic count, that is, in samples containing encapsulated probiotics reduced to a level of 8.51 log cfu/mL and 7.09 log cfu/mL after the mentioned storage period. The number of free viable cells in juice samples was lower than (107 cfu/g) the minimum recommend level. Similarly, the free cells showed a poor survival under simulated gastrointestinal conditions. Furthermore, encapsulation affected the physicochemical (pH, acidity, and Brix) and sensorial characteristics of the juice samples. Practical applications The probiotic delivery through carrier food and under hostile gastrointestinal conditions is a great challenge due to their low survival. The encapsulation technology can be used to protect the target delivery of probiotics. The encapsulation technology is a useful tool for delivering the probiotics for both dairy and nondairy food matrices. Encapsulation also ensures the recommended therapeutic level (1107–108 cfu) during transit and storage.

Development of a microchannel emulsification process for pancreatic beta cell encapsulation.

In this study, we developed a high‐throughput microchannel emulsification process to encapsulate pancreatic beta cells in monodisperse alginate beads. The process builds on a stirred emulsification and internal gelation method previously adapted to pancreatic cell encapsulation. Alginate bead production was achieved by flowing a 0.5–2.5% alginate solution with cells and CaCO3 across a 1‐mm thick polytetrafluoroethylene plate with 700 × 200 μm rectangular straight‐through channels. Alginate beads ranging from 1.5–3 mm in diameter were obtained at production rates exceeding 140 mL/hr per microchannel. Compared to the stirred emulsification process, the microchannel emulsification beads had a narrower size distribution and demonstrated enhanced compressive burst strength. Both microchannel and stirred emulsification beads exhibited homogeneous profiles of 0.7% alginate concentration using an initial alginate solution concentration of 1.5%. Encapsulated beta cell viability of 89 ± 2% based on live/dead staining was achieved by minimizing the bead residence time in the acidified organic phase fluid. Microchannel emulsification is a promising method for clinical‐scale pancreatic beta cell encapsulation as well as other applications in the pharmaceutical, food, and cosmetic industries.

In situ synthesis of poly (γ- glutamic acid)/alginate/AgNP composite microspheres with antibacterial and hemostatic properties

In the present work, a poly(γ-glutamic acid)/alginate/silver nanoparticle (PGA/Alg/AgNP) composite microsphere with excellent antibacterial and hemostatic properties was prepared by the in situ UV reduction and emulsion internal gelation method, and its potential application for antibacterial hemostatic dressing was explored. Well dispersed AgNPs were in situ synthesized by a UV reduction method with alginate as stabilizer and reductant. The AgNPs showed excellent antibacterial activities against both gram-negative and gram-positive bacteria. Additionally, the AgNPs prepared by the in-situ UV reduction exhibited better biocompatibility and antibacterial effects than those prepared by the conventional chemical reduction method. PGA/Alg/AgNP composite microspheres were then prepared with the AgNPs by an emulsion internal gelation method. Such microspheres were found to be a porous and hollow network with pH-sensitive swelling properties and excellent hemostatic performance, indicating its application potentials as an advanced antibacterial hemostatic material.

Lactoferrin-Loaded Alginate Microparticles to Target Clostridioides difficile Infection

Some forms of bovine lactoferrin (bLf) are effective in delaying Clostridioides difficile growth and preventing toxin production. However, therapeutic use of bLf may be limited by protein stability issues. The objective of this study was to prepare and evaluate colon-targeted, pH-triggered alginate microparticles loaded with bioactive bLf and to evaluate their anti-C difficile defense properties in vitro. Different forms of metal-bound bLf were encapsulated in alginate microparticles using an emulsification or internal gelation method. The microparticles were coated with chitosan to control protein release. In vitro drug release studies were conducted in pH-simulated gastrointestinal conditions to investigate the release kinetics of encapsulated protein. No significant release of metal-bound bLf was observed at acidic pH; however, on reaching simulated colonic pH, most of the encapsulated lactoferrin was released. The application of bLf (5 mg/mL) delivered from alginate microparticles to human intestinal epithelial cells significantly reduced the cytotoxic effects of toxins A and B as well as bacterial supernatant on Caco-2 and Vero cells, respectively. These results are the first to suggest that alginate-bLf microparticles show protective effects against C difficile toxin-mediated epithelial damage and impairment of barrier function in human intestinal epithelial cells. The future potential of lactoferrin-loaded alginate microparticles against C difficile deserves further study.

Rheological studies on nanocrystalline cellulose/alginate suspensions

Rheological behavior of mixtures containing nanocrystalline cellulose (CNC) and alginate was studied. A shear-thinning behavior was observed in all samples, which was progressively enhanced as a function of CNC and alginate concentrations. Electrostatic interactions between anionic alginate chains and anionic CNC rods promote physical gelation at small CNC concentrations (4wt%), resulting in soft gels with pronounced shear-thinning and solid-like behavior. Next, hydrogels were obtained using the internal gelation method, and the crosslinking kinetics were monitored by time sweep tests. The experimental data were well described by a modified Hill equation. Fourier transform infrared spectroscopy (FTIR) was performed in order to analyze the hydrogen bonding interactions that occur between CNC rods and alginate chains, and the alginate ionic crosslinking.

Synthesis of alginate-silica hybrid hydrogel for biocatalytic conversion by β-glucosidase in microreactor.

The organic-inorganic hybrid materials have been used in different fields to immobilize biomolecules since they offer many advantages. The aim of this study was to optimize and characterize the alginate-silica hybrid hydrogel as a stable and injectable form for microfluidic systems using internal gelation method and increase the stability and activity of immobilized enzyme for biocatalytic conversions as well. Characterization was carried out by scanning electron microscopy, energy dispersive spectroscopy/mapping, Brunauer-Emmett-Teller, Barrett-Joyner-Halenda, and Fourier-transform infrared spectroscopy analyses, and the shrinkages of monoliths were evaluated. Subsequent to optimizing the enzyme concentration (40 μg), hydrolytic conversion of 4-nitrophenyl β-d-glucopyranoside (pNPG) was performed to understand the behavior of the bioconversion in the microfluidic system. The yield was 94% which reached the equilibrium at 24 h indicating that the alginate-silica gel derived microsystem overcome some drawbacks of monolithic systems. Additionally, bioconversion of Ruscus aculeatus saponins was carried out at the same setup in order to obtain aglycon part, which has pharmaceutical significance. Although pure aglycon could not be achieved, an intermediate compound was obtained based on the HPLC analysis. The developed formulation can be utilized for various life science applications.