Determination of the glass-transition temperature of proteins from a viscometric approach

Optimizing performance of inhalable bacteriophage powders using human serum albumin (HSA)

In response to the growing threat of antibiotic resistance in pulmonary infections, bacteriophage therapy is emerging as a promising alternative to traditional antibiotics. We aimed to develop novel dry powder formulations for the pulmonary delivery of bacteriophages, using the Pseudomonas aeruginosa-specific phage PEV2 as a model. Our formulations combined human serum albumin (HSA) and lactose to enhance both phage stability and aerosol performance. A Box-Behnken experimental design was conducted to investigate the effects of HSA/lactose ratio, solute concentration of feed solution, and spray-drying inlet temperature. Our results demonstrated that incorporating 60% w/w HSA significantly improved aerosol performance by achieving a fine particle fraction above 50% and effectively delayed lactose recrystallization by maintaining an amorphous state at relative humidity levels of 80% or higher. Importantly, the optimized formulation (60% HSA/40% lactose) preserved phage viability with less than a 0.8 log10 reduction. Possible mechanisms contributing to stabilizing the phage powder formulations in HSA-lactose were discussed. These findings underscore the potential of a balanced HSA-lactose system as a robust powder formulation platform for pulmonary phage therapy.

Comparison of Sucrose and Trehalose for Protein Stabilization Using Differential Scanning Calorimetry

The disaccharide trehalose is generally acknowledged as a superior stabilizer of proteins and other biomolecules in aqueous environments. Despite many theories aiming to explain this, the stabilization mechanism is still far from being fully understood. This study compares the stabilizing properties of trehalose with those of the structurally similar disaccharide sucrose. The stability has been evaluated for the two proteins, lysozyme and myoglobin, at both low and high temperatures by determining the glass transition temperature, Tg, and the denaturation temperature, Tden. The results show that the sucrose-containing samples exhibit higher Tden than the corresponding trehalose-containing samples, particularly at low water contents. The better stabilizing effect of sucrose at high temperatures may be explained by the fact that sucrose, to a greater extent, binds directly to the protein surface compared to trehalose. Both sugars show Tden elevation with an increasing sugar-to-protein ratio, which allows for a more complete sugar shell around the protein molecules. Finally, no synergistic effects were found by combining trehalose and sucrose. Conclusively, the exact mechanism of protein stabilization may vary with the temperature, as influenced by temperature-dependent interactions between the protein, sugar, and water. This variability can make trehalose to a superior stabilizer under some conditions and sucrose under others.

Prediction of frozen virus stability based on degradation mechanisms, real-time data and modeling

Aim: Critical virus reagents in regulated bioanalytical assays require stability monitoring. Although stability at ultralow frozen temperatures is generally assumed, published data are limited and real-time studies are time consuming. Materials & methods: The authors reviewed literature data, typical mechanisms of molecular degradation, glass transition temperatures of commonly used buffers and available real-time storage data to model frozen virus reagent stability. Results: Storage at ultralow temperatures below the glass transition temperature was critical for virus stability. Modeling of real-time data suggested that virus potency remained within 0.5 log10 of its starting potency at a probability of >99, 90 and 73% after 10, 20 and 30 years, respectively. Conclusion: The study supports the practice of virus storage at -70°C or below for 20–30 years.

Insights into the Properties and Potential Applications of Renewable Carbohydrate-Based Ionic Liquids: A Review

Carbohydrate-derived ionic liquids have been explored as bio-alternatives to conventional ionic liquids for over a decade. Since their discovery, significant progress has been made regarding synthetic methods, understanding their environmental effect, and developing perspectives on their potential applications. This review discusses the relationships between the structural properties of carbohydrate ionic liquids and their thermal, toxicological, and biodegradability characteristics in terms of guiding future designs of sugar-rich systems for targeted applications. The synthetic strategies related to carbohydrate-based ionic liquids, the most recent relevant advances, and several perspectives for possible applications spanning catalysis, biomedicine, ecology, biomass, and energy conversion are presented herein.

Effect of aqueous medium on low-frequency dynamics, chemical activity and physical properties of a spherical virus

In this work, we have studied the effect of size and aqueous medium on the low-frequency dynamics, physical properties like melting temperature and glass transition temperature and chemical properties like catalytic activation energy of spherical virus using Lindemann's criteria and Arrhenius relation under their dynamic limit. The melting temperature and catalytic activation energy decrease with decreasing size of spherical virus. The glass transition temperature which increases with decreasing size of the virus is analyzed through the size dependent melting temperature. The melting temperature and catalytic activation energy of spherical virus of particular size increases when it is embedded in glycerol or water due to mismatch of the physical properties at the interface of virus and surrounding medium. In addition, the glass transition temperature of free and glycerol/water embedded virus using low-frequency vibrational modes has been calculated under the framework of elastic continuum approximation model. The glass transition temperature of spherical virus decreases with size when embedded in glycerol or water. A correlation between [Formula: see text] and [Formula: see text] is also drawn for spherical viruses. The study can be useful for spherical virus borne therapy i.e. in detecting and killing of the spherical viruses using a principle based on acoustic phonons (sound waves) resonance.Communicated by Ramaswamy H. Sarma.

High pressure effects on the structural functionality of condensed globular-protein matrices

High pressure technology is the outcome of consumer demand for better quality control of processed foods. There is great potential to apply HPP to condensed systems of globular proteins for the generation of industry-relevant biomaterials with advanced techno- and biofunctionality. To this end, research demonstrates that application of high hydrostatic pressure generates a coherent structure and preserves the native conformation in condensed globular proteins, which is an entirely unexpected but interesting outcome on both scientific and technological grounds. In microbiological challenge tests, high pressure at conventional commercial conditions, demonstrated to effectively reduce the concentration of typical Gram negative or Gram positive foodborne pathogens, and proteolytic enzymes in high-solid protein samples. This may have industrial significance in relation to the formulation and stabilisation of "functional food" products as well as in protein ingredients and concentrates by replacing spray dried powders with condensed HPP-treated pastes that maintain structure and bioactivity. Fundamental concepts and structural functionality of condensed matrices of globular proteins are the primary interest in this mini-review, which may lead to opportunities for industrial exploitation, but earlier work on low-solid systems is also summarised presently to put recent developments in context of this rapidly growing field.