Control of microenvironment around enzymes by hydrogels

Exploring the Potential of Various Cyclodextrin-Based Derivatives in Enzyme Supramolecular Engineering

Enzyme stability and activity are pivotal factors for their implementation in different industrial applications. Enzyme supramolecular engineering relies on the fabrication of a tailor-made enzyme nano-environment to ensure enzyme stability without impairing activity. Cyclodextrins (CDs), cyclic oligomers of glucose, act as protein chaperones and stabilize, upon interaction with hydrophobic amino acid residues exposed at the protein surface, its three-dimensional structure. When used to build an organosilica layer shielding an enzyme, they enhance the protective effect of this layer. In the present study, we systematically assessed the protective effects of three organosilane derivatives based on ɑ-, β- and γ-CDs. A model lipase enzyme was immobilized at the surface of silica nanoparticles and shielded in an organosilica layer containing these organosilanes. Besides layer thickness optimization, the effect of different stressors (i. e., temperature, SDS, urea) was tested. Our results showed that organosilica layers produced with CDs improve enzyme thermal stability. They also support enzyme refolding after denaturation under chaotic conditions. Additionally, we demonstrated that the protective effect of the smallest CD derivative tested, namely ɑ-CD, surpassed the other macrocycles studied for conferring the immobilized enzyme with higher resistance to stress conditions. This protection strategy was also applied to a thermostable β-galactosidase enzyme.

Rationally Tailored Mesoporous Hosts for Optimal Protein Encapsulation

Proteins play important roles in the therapeutic, medical diagnostic, and chemical catalysis industries. However, their potential is often limited by their fragile and dynamic nature outside cellular environments. The encapsulation of proteins in solid materials has been widely pursued as a route to enhance their stability and ease of handling. Nevertheless, the experimental investigation of protein interactions with rationally designed synthetic hosts still represents an area in need of improvement. In this work, we leveraged the tunability and crystallinity of metal-organic frameworks (MOFs) and developed a series of crystallographically defined protein hosts with varying chemical properties. Through systematic studies, we identified the dominating mechanisms for protein encapsulation and developed a host material with well-tailored properties to effectively encapsulate the protein ubiquitin. Specifically, in our mesoporous hosts, we found that ubiquitin encapsulation is thermodynamically favored. A more hydrophilic encapsulation environment with favorable electrostatic interactions induces enthalpically favored ubiquitin-MOF interactions, and a higher pH condition reduces the intraparticle diffusion barrier, both leading to a higher protein loading. Our findings provide a fundamental understanding of host-guest interactions between proteins and solid matrices and offer new insights to guide the design of future protein host materials to achieve optimal protein loading. The MOF modification technique used in this work also demonstrates a facile method to develop materials easily customizable for encapsulating proteins with different surface properties.

Recent Advances in Smart Hydrogels Prepared by Ionizing Radiation Technology for Biomedical Applications

Materials with excellent biocompatibility and targeting can be widely used in the biomedical field. Hydrogels are an excellent biomedical material, which are similar to living tissue and cannot affect the metabolic process of living organisms. Moreover, the three-dimensional network structure of hydrogel is conducive to the storage and slow release of drugs. Compared to the traditional hydrogel preparation technologies, ionizing radiation technology has high efficiency, is green, and has environmental protection. This technology can easily adjust mechanical properties, swelling, and so on. This review provides a classification of hydrogels and different preparation methods and highlights the advantages of ionizing radiation technology in smart hydrogels used for biomedical applications.

Three-Dimensional Chiral Supramolecular Microenvironment Strategy for Enhanced Biocatalysis

How the three-dimensional (3D) chiral environment affects the biocatalysis remains an important issue, thereby inspiring the development of a microenvironment that highly mimics the natural features of enzyme to guarantee enhanced biocatalysis. In this study, two gelators bearing d/l-phenylalanine as chiral centers are designed to construct the 3D chiral catalytic microenvironment for enhancing the biocatalysis of lipase. Such a microenvironment is programmed through chiral transmission of chirality from molecular chirality to achiral polymers. It shows that the chirality of the microenvironment evidently influences the catalytic efficiency of immobilized lipase inside the system, and the 3D microenvironment constructed by right-handed helical nanostructures can enhance the catalytic activity of lipase inside as high as 10-fold for catalyzing 4-nitrophenyl palmitate (NPP) to 4-nitrophenol (NP) and 1.4-fold for catalyzing lipids to triglycerides (TGs) in 3T3-L1 cells than that of the achiral microenvironment. Moreover, the 3D chiral microenvironment has the merits of good catalytic efficiency, high storage stability, and efficient recyclability. This strategy of designing a 3D chiral microenvironment suitable for biocatalysis will overcome the present limitations of enzymatic immobilization in traditional materials and enhance the understanding of biocatalysis.

Harnessing P450 Enzyme for Biotechnology and Synthetic Biology

Cytochrome P450 enzymes (P450s, CYPs) catalyze the oxidative transformation of a wide range of organic substrates. Their functions are crucial to xenobiotic metabolism and steroid transformation in humans and other organisms. The enzymes are promising for synthetic biology applications but limited by several drawbacks including low turnover rates, poor stability, the dependance of expensive cofactors and redox partners, and the narrow substrate scope. To conquer these obstacles, emerging strategies including substrate engineering, usage of decoy and decoy-based small molecules auxiliaries, designing of artificial enzyme cascades and the incorporation of materials have been explored based on the unique properties of P450s. These strategies can be applied to a wide range of P450s and can be combined with protein engineering to improve the enzymatic activities. This minireview will focus on some recent developments of these strategies which have been used to leverage P450 catalysis. Remaining challenges and future opportunities will also be discussed.