Effect of solvent and additives on the electrospinnability of BSA solutions.

Electrospun nanofibrous membranes have attracted the interest of the scientific community over the past decades due to their unique properties (e.g., high surface area, enzyme encapsulation high efficiency in filtering). Among the most promising membranes are those derived from natural polymers, which are not based on fossil fuels and most of them are highly biocompatible. In this regard, this study is focused on the development and characterization of electrospun nanofibrous membranes of bovine serum albumin (BSA) with potential applications in several fields, from tissue engineering to advanced filtering. Although the globular structure of BSA hinders the generation of nanofibers, some previous studies have succeeded in its electrospinning. However, they made use of either toxic reagents or co-electrospinning with synthetic polymers, which resulted in poorer biocompatibility. To prevent this, the present study explores the impact of non-hazardous reagents on the formation of BSA nanofibers. As a result, it was observed that the addition of ethanol (EtOH) in the solvent mixture and the thermal denaturation of BSA favored the electrospraying of nanoparticles (∼ 300 nm). It was also noticed that the presence of hydroxypropyl methylcellulose (HPMC) favors the formation of nanofibers (∼ 60 nm). However, bead formation was found in these membranes. This work contributes to clarifying the influence of solvents and surfactants when proteins are electrospun, enabling the manufacture of bio-based nanofibrous mats with applications in different fields (e.g., filtering, biomaterials, active packaging).

Development of superabsorbent soy protein-based bioplastic matrices with incorporated zinc for horticulture.

BACKGROUND: The use of superabsorbent materials in horticulture has spread recently. These materials, which can retain water and release it as crops need it, have strong advantages such as the efficient use of water in periods of drought. However, these materials are made of synthetic polymers, which present problems of degradability and, sometimes, toxicity. For this reason, the main objective of this work is the development of biodegradable superabsorbent bioplastic (SAB) matrices using a soy protein isolate (SPI) as raw material. Zinc is also incorporated into these bioplastic matrices as an essential micronutrient for plants, to increase their added value. RESULTS: The incorporation of zinc chelated with 2,2',2″,2‴-(Ethene-1,2-diyldinitrilo)tetraacetic acid (Zn EDTA) (a salt with which the micronutrient is incorporated) into soy protein-based bioplastic matrices improved their superabsorbent capacity and provided a controlled release of water and nutrients to the crops. CONCLUSIONS: The results show the strong potential for the use of these bioplastic matrices in horticulture as superabsorbent materials that can release nutrients in a controlled manner. © 2019 Society of Chemical Industry.

Development of crayfish bio-based plastic materials processed by small-scale injection moulding.

BACKGROUND: Protein has been investigated as a source for biodegradable polymeric materials. This work evaluates the development of plastic materials based on crayfish and glycerol blends, processed by injection moulding, as a fully biodegradable alternative to conventional polymer-based plastics. The effect of different additives, namely sodium sulfite or bisulfite as reducing agents, urea as denaturing agent and L-cysteine as cross-linking agent, is also analysed. RESULTS: The incorporation of any additive always yields an increase in energy efficiency at the mixing stage, but its effect on the mechanical properties of the bioplastics is not so clear, and even dampened. The additive developing a greater effect is L-cysteine, showing higher Young's modulus values and exhibiting a remnant thermosetting potential. Thus, processing at higher temperature yields a remarkable increase in extensibility. CONCLUSION: This work illustrates the feasibility of crayfish-based green biodegradable plastics, thereby contributing to the search for potential value-added applications for this by-product.

Interfacial and oil/water emulsions characterization of potato protein isolates.

Interfacial and emulsifying properties of potato protein isolate (PPI) have been studied to evaluate its potential application to stabilize oil/water emulsions at two pH values (2 and 8). The amount, type, and solubility of proteins and the size of aggregates have been determined in aqueous dispersion. Air-water and oil-water interfacial properties (adsorption, spreading, and viscoelastic properties) have been determined as a function of concentration and pH using soluble phases of PPI. The behavior of PPI stabilized oil/water emulsions has been then analyzed by droplet size distribution measurements and interfacial concentration. PPI exhibits low solubility over a wide range of pH values, with the presence of submicrometer aggregates. The pH value exerts a negligible effect on interfacial tension (oil-water) or surface pressure (air-water) but displays very important differences in viscoelastic properties of the interfacial films formed between oil and water. In this sense, pH 8 provides a major elastic response at oil-water interfaces as compared to pH 2. In relation with this result, a much higher ability to produce fine and stable emulsions is noticed at pH 8 as compared to pH 2. Consequently, there is an evident relationship between the rheological properties of the oil-water interfacial films and the macroscopic emulsion behavior.

Water-ethylene glycol cationic dimeric micellar solutions: aggregation, micellar growth, and characteristics as reaction media.

Effects of ethylene glycol (EG) addition on the micellization and on the micellar growth in two aqueous didodecyl dicationic dibromide surfactant, 12-s-12,2Br- (s=2, 6) solutions, with the weight percentage of EG up to 50%, have been investigated. An increment in the amount of EG makes the aggregation process less spontaneous due to the water-EG mixtures being better solvents for the cationic dimeric surfactant molecules than pure water (solvophobic effect). Results show that C*, the surfactant concentration where the sphere-to-rod transition occurs, increases when EG content in the bulk phase increases. The amount of the organic solvent influences C* principally through the decrease in the hydrocarbon/bulk phase interfacial tension (air/bulk phase surface tension) caused by its presence. Changes in the aggregation number, in the micropolarity, in the microviscosity, and in the rheological behavior accompanying micellar growth were studied in the water-EG micellar solutions. Kinetic studies provide information about the characteristics of the dimeric micelles as microreactors. Kinetic data also show that an increase in the surfactant concentration leads to micellar growth.