An Efficient, Recyclable, and Stable Immobilized Biocatalyst Based on Bioinspired Microcapsules-in-Hydrogel Scaffolds

Abstract

Design and preparation of high-performance immobilized biocatalysts with exquisite structures and elucidation of their profound structure-performance relationship are highly desired for green and sustainable biotransformation processes. Learning from nature has been recognized as a shortcut to achieve such an impressive goal. Loose connective tissue, which is composed of hierarchically organized cells by extracellular matrix (ECM) and is recognized as an efficient catalytic system to ensure the ordered proceeding of metabolism, may offer an ideal prototype for preparing immobilized biocatalysts with high catalytic activity, recyclability, and stability. Inspired by the hierarchical structure of loose connective tissue, we prepared an immobilized biocatalyst enabled by microcapsules-in-hydrogel (MCH) scaffolds via biomimetic mineralization in agarose hydrogel. In brief, the in situ synthesized hybrid microcapsules encapsulated with glucose oxidase (GOD) are hierarchically organized by the fibrous framework of agarose hydrogel, where the fibers are intercalated into the capsule wall. The as-prepared immobilized biocatalyst shows structure-dependent catalytic performance. The porous hydrogel permits free diffusion of glucose molecules (diffusion coefficient: ∼6 × 10(-6) cm(2) s(-1), close to that in water) and retains the enzyme activity as much as possible after immobilization (initial reaction rate: 1.5 × 10(-2) mM min(-1)). The monolithic macroscale of agarose hydrogel facilitates the easy recycling of the immobilized biocatalyst (only by using tweezers), which contributes to the nonactivity decline during the recycling test. The fiber-intercalating structure elevates the mechanical stability of the in situ synthesized hybrid microcapsules, which inhibits the leaching and enhances the stability of the encapsulated GOD, achieving immobilization efficiency of ∼95%. This study will, therefore, provide a generic method for the hierarchical organization of (bio)active materials and the rational design of novel (bio)catalysts.

Preparation of Ultrathin, Robust Nanohybrid Capsules through a “Beyond Biomineralization” Method

“…However, k cat decreased from 418.7 to 14.3 s –1 after immobilization, suggesting the increased diffusion resistance from the capsule wall. As compared to the result in our previous work, k cat of immobilized GOD is increased by ∼26 times (14.3 vs 0.539 s –1 ), which should be attributed to the ultrathin capsule wall. Finally, the recycling stability of the GOD@capsule system was examined (Figure f), which showed elevation with the increase of the PAH concentration.…”

Fabrication of Hierarchical Macroporous Biocompatible Scaffolds by Combining Pickering High Internal Phase Emulsion Templates with Three-Dimensional Printing

“…Bone tissue engineering provides a promising approach to repair damaged and diseased bones in clinical applications. − In this regard, stem cells are cultured in a three-dimensional porous biocompatible/biodegradable scaffold followed by in vivo implantation. − It is highly desirable for the fabricated porous scaffold to mimic the critical characteristics of the natural extracellular matrix (ECM), since it serves as an artificial ECM in this approach. , Regarding ingredients, materials employed to fabricate scaffolds should be biocompatible and possess an appropriate biodegradability at a rate commensurate with remodeling. − With respect to structure, an ideal scaffold ought to be highly porous with hierarchical and interconnected pores. − A macroporous material (pores of a few hundred micrometers) would maintain the structural stability of the scaffold, promote cell adhesion and proliferation, and allow transport of nutrients. Materials with medium-sized pores (diameter of tens of micrometers) would promote vascularization and facilitate the transport of metabolic waste.…”

Hydrogel‐Immobilized Coacervate Droplets as Modular Microreactor Assemblies

“…Immobilizing micro‐compartmentalized synthetic objects, such as porous microbeads, liposomes, polymersomes, and liquid droplets, in three‐dimensional (3D) hydrogels offers diverse opportunities for drug delivery and tissue engineering, the assembly of cell‐like tissues and organization of spatially distributed microreactors for enhanced mechanical performance, durability, and reusability . For example, supramolecular nested microbeads were developed as building blocks to construct macroscopic self‐healing scaffolds, and enzyme‐containing hybrid microcapsules hierarchically organized in agarose hydrogels to facilitate recycling of an immobilized biocatalyst . As individual hydrogels can be shaped and assembled into higher‐order arrangements by 3D printing and controlled crosslinking, they provide a potential pathway to the fabrication of soft modular materials based on the integration of functionally encoded hydrogel building blocks .…”