Self-Assembled Regenerated Silk Fibroin Microsphere-Embedded Fe₃O₄ Magnetic Nanoparticles for Immobilization of Zymolyase

Abstract

Cytoplasm of Saccharomyces cerevisiae yeast cells contains a significant amount of desired intracellular products for both industrial utility and academic research. To recover intracellular compounds, it is necessary to break the yeast cells with high efficiency, which, under certain circumstances, requires the use of the lytic enzyme zymolyase to completely digest the cell walls. A promising strategy for zymolyase immobilization on silk fibroin (SF) was developed. SF/Fe3O4 magnetic microspheres (MMs) were constructed by solvent (ethanol)-induced self-assembly of SF surrounding Fe3O4 magnetic nanoparticles (MNs), which were synthesized by a coprecipitation method. Zymolyase was covalently bonded on the surface of the SF/Fe3O4 MMs by a photochemical cross-linking method to produce robust biocatalysts of zymolyase/SF/Fe3O4. The chemical, magnetic, and morphological properties of the MM supports and the immobilized zymolyase were investigated. Enzymolysis results demonstrated that the immobilized zymolyase showed good activity and stability for digesting yeast cell walls, and the biocatalyst can be readily recycled through convenient magnetic separation for reuse. At the optimum pH = 7.5, the immobilized zymolyase maintained 84% of the activity of the free zymolyase and retained 41% of its initial activity after four times of reuse. At unfavorable acidic pH = 4, the immobilized zymolyase retained 81% of its initial activity, while the free zymolyase showed no significant activity. Consequently, the SF/Fe3O4 MMs exhibit superior performance in terms of immobilizing enzymes, which have a good prospect in the biological application.

Bioinspired synthesis of fiber-shaped silk fibroin-ferric oxide nanohybrid for superior elimination of antimonite

“…A sharp peak at 3276 cm -1 was ascribed to the stack stretching vibration of N-H and O-H. The characteristic peaks responsible for the secondary structures of SF at around1624 and 1520 cm -1 were assigned to β -sheets, amide Ⅰ band and amide Ⅱ band [ 26 , 27 ]. In the spectra of SNF/ferric oxide nanohybrid, the N-H stretching shifted to left, and the intensity of the amide Ⅱ band peaks at 1624 and 1520 cm -1 decreased, suggesting a lower β -sheet content after chelating with iron ions.…”

Review on Fabrication and Application of Regenerated Bombyx mori Silk Fibroin Materials

“…For example, Xiao et al fabricated regenerated silk fi broin microsphere-embedded Fe 3 O 4 magnetic nanoparticles for immobilization of zymolyase through a controllable ethanol-induced interface self-assembly. The prepared microsphere exhibited high immobilization effi ciency [67]. Spray-drying, jet-breaking, and electro-spraying are similar technologies, which involve the breaking down of the aqueous silk fi broin fl ow into small droplets by force [8,68].…”

New Silk Road: From Mesoscopic Reconstruction/Functionalization to Flexible Meso‐Electronics/Photonics Based on Cocoon Silk Materials

“…[53] Copyright 2018, Wiley-VCH. Materials: Graphene, [15] carbon dots (CDs), [46] CNTs, [21] Ag nanocluster, [6] Fe 3 O 4 , [49] QDs, [48] cellulose, [45] chitin, [56] chitosan, [57] hydroxyapatite, [58] calcium carbonate, [59] titanium dioxide, [60] peptide, [53] keratin, [13] and gelatin. [54] comparing the simple and ideal mixing of the SF materials to that with the incorporation of nano seeds.…”

“…[14,48] Similarly, magnetic SF can be fabricated after interaction with Fe 3 O 4 NPs. [49] Some nanofiber materials with excellent filmforming and fiber-forming properties can enhance the mechanical performances of the protein materials after hybridization with silk protein. The assembled materials are mechanically stable, non-toxic, sustainable, and biodegradable, which are beneficial for various applications including waste water ultrafiltration and construction of tissue engineering scaffolds and biocompatible devices.…”