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

Abstract

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.

Transformer Hydrogels: A Review

“…ALP causes the formation of a calcium phosphate precipitate due to the concentration of phosphate ions by the cleavage of the organic phosphate causing morphological changes in the hydrogels . The enzyme phytase has also been incorporated into chitosan‐based hydrogels with calcium glycerophosphate to achieve mineralization . These enzymatic changes can dramatically alter the local mechanical properties of the gel of relevance to transformer hydrogels…”

The Promises and the Challenges of Biotransformations in Microflow

“…Further introduction of nanomaterials including biomimetic structures in microreactors, together with the genetic introduction of tags in bacterial cells and enzymes, offers the possibility for more specific immobilization and spatial organization of biocatalysts at specific sites, especially using DNA nanotechnology as a programmable tool for engineering multienzyme catalysis . Microflow format was found beneficial also for packed‐bed reactors (Figures f and e) with biocatalysts immobilized in porous beads, on streptavidin‐coated superparamagnetic microbeads, in electrospun nanomats, or in various hydrogels, recently also prepared as alginate‐silica hybrids, which have the advantages of homogenous structure, better stability, and nontoxicity, and are injectable . Miniaturized packed‐bed reactors enabled not only very high enzyme loads, but also very good accessibility and operational stability of biocatalysts due to diminished fluid flow anomalies such as back mixing and dead zones, and very low‐pressure drop …”

“…[95] Microflow format was found beneficial also for packed-bed reactors (Figures 2f and 3e) with biocatalysts immobilized in porous beads, [30,50,77] on streptavidin-coated superparamagnetic microbeads, [55,57,58] in electrospun nanomats, [51] or in various hydrogels, [36,52] recently also prepared as alginate-silica hybrids, which have the advantages of homogenous structure, better stability, and nontoxicity, and are injectable. [96] Miniaturized packed-bed reactors enabled not only very high enzyme loads, but also very good accessibility and operational stability of biocatalysts due to diminished fluid flow anomalies such as back mixing and dead zones, and very low-pressure drop. [36,51,66] Moreover, microflow reactors are ideally suited for simultaneous inline purification and immobilization of enzymes, often achieved through tagged enzyme noncovalent interactions with adequate supports.…”

Hydrogel-Based Enzyme and Cofactor Co-Immobilization for Efficient Continuous Transamination in a Microbioreactor

“…One of the simplest and non-invasive techniques to immobilize biocatalysts is their entrapment in porous structures by cross-linking different (bio)polymers such as alginates ( Onbas and Yesil-Celiktas, 2019 ), chitosan ( Kim et al, 2017 ), or synthetic polymers such as polyvinyl alcohol (PVA) ( Bajić et al, 2017 ). We have previously reported the use of a copolymer hydrogel of PVA and alginate to immobilize yeast cells.…”