Abstract
Two simple and easily reproducible methods for the immobilization of β-galactosidase (β-gal) from Aspergillus oryzae on electrospun gelatin nanofiber mats (GFM) were developed. The process was optimized regarding the electrospinning solvent system and the subsequent cross-linking of GFM in order to increase their stability in water. β-Gal was covalently immobilized on activated gelatin nanofiber mats with hexamethylenediamine (HMDA) as a bifunctional linker and secondly via entrapment into the gelatin nanofibers during the electrospinning process (suspension electrospinning). Optimal immobilization parameters for covalent immobilization were determined to be at pH 7.5, 40 °C, β-gal concentration of 1 mg/mL and immobilization time of 24.5 h. For suspension electrospinning, the optimal immobilization parameters were identified at pH 4.5 and β-gal concentration of 0.027 wt.% in the electrospinning solution. The pH and temperature optima of immobilized β-gal shifted from 30 °C, pH 4.5 (free enzyme) to pH 3.5, 50 °C (covalent immobilization) and pH 3.5, 40 °C (suspension electrospinning). Striking differences in the Michaelis constant (KM) of immobilized β-gal compared with free enzyme were observed with a reduction of KM up to 50% for immobilized enzyme. The maximum velocity (vmax) of immobilization by suspension electrospinning was almost 20 times higher than that of covalent immobilization. The maximum GOS yield for free β-gal was found to be 27.7% and 31% for immobilized β-gal.
Highlights
Electrospinning is a versatile and reasonable method for generating continuous nanofibers from a variety of natural or synthetic polymers with diameters ranging from a few micrometers to several nanometers
The aim of this study is to develop an easy, efficient, and economically viable immobilization procedure for the immobilization of β-galactosidase from Aspergillus oryzae on electrospun gelatin nanofiber mats via covalent binding and encapsulation
For the immobilization of β-gal onto electrospun gelatin fiber mats, an adequate solvent system had to be determined (a) to be able to dissolve β-gal evenly in the electrospinning solution without a rigorous reduction in the enzymatic activity and (b) to create a solvent system that provides an easy-to-spin gelatin solution resulting in small-diameter fiber mats
Summary
Electrospinning is a versatile and reasonable method for generating continuous nanofibers from a variety of natural or synthetic polymers with diameters ranging from a few micrometers to several nanometers. When applying an electric field, the electrospinning solution becomes charged. Mutual electric repulsion antagonizes the surface tension of the solution. After reaching a critical value of the electric field, the electric repulsion overcomes the surface tension and a liquid droplet breaks out forming a typical conic shape, known as the Taylor cone. The solvent from the traveling jet evaporates quickly on its way from the tip of the spinneret to the collector, and the jet undergoes simultaneously complex structure forming processes, which result in a tremendous fiber stretch on a proportionally short distance [1, 2]. The newly formed nanofibers are randomly collected onto the collector. Electrospun nanofiber mats have many advantages, e.g., an enormous surface-to-mass ratio, extensive convertibility, easy handling, and the malleability to conform fiber diameters, shapes, and pore structures. Electrospun nanofiber mats could be an excellent material for the immobilization of enzymes since fine nanofiber mats only have little diffusion limitations and offer a big specific surface with plenty of space for chemical bonding or inclusion of great enzyme quantities
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
