The Core-Shell Structure, Not Sugar, Drives the Thermal Stabilization of Single-Enzyme Nanoparticles

Trehalose-Releasing Nanogels: Study on Trehalose Release and Insights into Selected Biologically Relevant Aspects

Trehalose has sparked considerable interest in a variety of pharmaceutical applications as well as in cryopreservation. Recently, there have been growing efforts in the development of trehalose delivery nanocarriers to address the issue of the poor bioavailability of trehalose. The majority of the strategies comprise physical entrapment of trehalose, since its covalent, yet biolabile, conjugation is challenging. Here, we present research on trehalose-releasing nanogels, in which covalent, yet biolabile, conjugation of trehalose was achieved through the co-incorporation of trehalose (meth)acrylate(s) together with hydrophilic primary/secondary acrylamides in one polymeric network. In this case, the primary and secondary amide groups participated in ester hydrolysis in the (meth)acrylate units, making the hydrolysis feasible under physiologically relevant conditions. A set of nanogels with precisely selected compositions were synthesized, characterized, and then studied to evaluate the influence of various structural and environmental factors on the release rate of trehalose. The study also provides insights into some other aspects that are important in view of potential biomedical applications, including specific interactions of nanogels through their terminal α-d-glucopyranosyl moieties from pendant trehalose, protein corona formation, and cellular uptake.

Enhanced Thermal and Storage Stability of Glucose Oxidase via Encapsulation in Chitosan-Coated Alginate and Carboxymethyl Cellulose Gel Particles

Glucose oxidase (GOD) is widely used as an important oxidoreductase in various fields. However, maintaining the vitality and stability of GOD under environmental stress is a challenge. To improve the thermal and storage stability of GOD, this study constructed sodium alginate-carboxymethyl cellulose sodium gel particles (SA/CMC) and chitosan-coated SA/CMC gel particles (CS/SA/CMC) of GOD. The encapsulation efficiency (EE), gel particle structure, stability, and release behavior of GOD were evaluated. The results showed that the thermal stability of GOD encapsulated in SA/CMC and CS/SA/CMC gel particles was improved by approximately 2.8-fold and 4.3-fold compared with the free enzyme at 85 °C, respectively. In addition, CS/SA/CMC gel particles enhanced the enzyme activity retention rate of GOD to over 80% during storage at 4 °C for four weeks. Both SA/CMC and CS/SA/CMC gel particles loaded with GOD had more than 70% of the enzymes released during the simulated gastrointestinal experiment. The results demonstrated that encapsulating GOD in SA/CMC and CS/SA/CMC gel particles could improve its thermal stability and storage stability, which is conducive to further expanding the application of GOD in food, pharmaceutical and feed industries.

Encapsulation of enzymes in food industry using spray drying: recent advances and process scale-ups

Enzymes are widely used in the food industry due to their ability in improving the functional, sensory, and nutritional properties of food products. However, their poor stability under harsh industrial conditions and their compromised shelf-lives during long-term storage limit their applications. This review introduces typical enzymes and their functionality in the food industry and demonstrates spray drying as a promising approach for enzyme encapsulation. Recent studies on encapsulation of enzymes in the food industry using spray drying and the key achievements are summarized. The latest developments including the novel design of spray drying chambers, nozzle atomizers and advanced spray drying techniques are also analyzed and discussed in depth. In addition, the scale-up pathways connecting laboratory scale trials and industrial scale productions are illustrated, as most of the current studies have been limited to lab-scales. Enzyme encapsulation using spray drying is a versatile strategy to improve enzyme stability in an economical and industrial viable way. Various nozzle atomizers and drying chambers have recently been developed to increase process efficiency and product quality. A comprehensive understanding of the complex droplet-to-particle transformations during the drying process would be beneficial for both process optimization and scale-up design.

Synthesis and Application of Trehalose Materials

Trehalose is a naturally occurring, nonreducing disaccharide that is widely used in the biopharmaceutical, food, and cosmetic industries due to its stabilizing and cryoprotective properties. Over the years, scientists have developed methodologies to synthesize linear polymers with trehalose units either in the polymer backbone or as pendant groups. These macromolecules provide unique properties and characteristics, which often outperform trehalose itself. Additionally, numerous reports have focused on the synthesis and formulation of materials based on trehalose, such as nanoparticles, hydrogels, and thermoset networks. Among many applications, these polymers and materials have been used as protein stabilizers, as gene delivery systems, and to prevent amyloid aggregate formation. In this Perspective, recent developments in the synthesis and application of trehalose-based linear polymers, hydrogels, and nanomaterials are discussed, with a focus on utilization in the biomedical field.

Controlled growth of redox polymer network on single enzyme molecule for stable and sensitive enzyme electrode

The electrochemical applications of enzymes are often hampered by poor enzyme stability and low electron conductivity. In this work, a novel enzyme nanogel based on atom transfer radical polymerization (ATRP) has been developed for highly sensitive detection of glucose based on ferrocene (Fc) embedded in crosslinked polymer network nanogel. Enzyme surfaces are successively modified with Br initiator, and then in situ atom transfer radical polymerization (ATRP) was performed to build up crosslinked polyacrylamide network. The resulting single enzyme nanogel (ATRP-SEG) is uniform in size fairly. ATRP-SEG reveals bi-phasic inactivation, and the half-life of stable ATRP-SEG after 18-day incubation at 50 °C is 47 days, which is 197 times longer than that of free Gox (5.7 h). By introducing a ferrocene (Fc) containing redox polymer, poly(acrylamide-co-vinylferrocene), the half-life of Fc-ATRP-SEG after 18-day incubation at 50 °C is 49 days. Fc-ATRP-SEG is used for preparation of glucose-sensing electrode, and the sensitivity of Fc-ATRP-SEG electrode is 111 μA cm^-2 mM^-1, which is 366 and 1270 times higher than those of free GOx (0.303 μA cm^-2 mM^-1) and ATRP-SEG (0.0874 μA cm^-2 mM^-1), respectively. Fc-ATRP-SEG electrode maintained 90% of initial current density under 4 °C storage condition and repetitive usages every day for 7 days. Even the electrode repeatedly used in continuous harsh condition (250 rpm, room temperature), the current density maintained 96% after 12 h incubation at operational condition.

Immobilization-Stabilization of β-Glucosidase for Implementation of Intensified Hydrolysis of Cellobiose in Continuous Flow Reactors

Cellulose saccharification to glucose is an operation of paramount importance in the bioenergy sector and the chemical and food industries, while glucose is a critical platform chemical in the integrated biorefinery. Among the cellulose degrading enzymes, β-glucosidases are responsible for cellobiose hydrolysis, the final step in cellulose saccharification, which is usually the critical bottleneck for the whole cellulose saccharification process. The design of very active and stable β-glucosidase-based biocatalysts is a key strategy to implement an efficient saccharification process. Enzyme immobilization and reaction engineering are two fundamental tools for its understanding and implementation. Here, we have designed an immobilized-stabilized solid-supported β-glucosidase based on the glyoxyl immobilization chemistry applied in porous solid particles. The biocatalyst was stable at operational temperature and highly active, which allowed us to implement 25 °C as working temperature with a catalyst productivity of 109 mmol/min/gsupport. Cellobiose degradation was implemented in discontinuous stirred tank reactors, following which a simplified kinetic model was applied to assess the process limitations due to substrate and product inhibition. Finally, the reactive process was driven in a continuous flow fixed-bed reactor, achieving reaction intensification under mild operation conditions, reaching full cellobiose conversion of 34 g/L in a reaction time span of 20 min.

Structurally analogous trehalose and sucrose glycopolymers – comparative characterization and evaluation of their effects on insulin fibrillation

Comprehensive comparative characterization of highly structurally similar, RAFT-prepared trehalose and sucrose glycopolymers.