Kinetics of thermally-induced conformational transitions in soybean protein films

Facile Fabrication of Self-Healable and Antibacterial Soy Protein-Based Films with High Mechanical Strength

Soy protein isolate (SPI), a ubiquitous and readily available biopolymer, has drawn increasing attention because of its sustainability, abundance, and low price. However, the poor mechanical properties, tedious performance adjustments, irreversible damage, and weak microorganism resistance have limited its applications. In this study, a facile but delicate strategy is proposed to fabricate an excellently self-healable and remarkably antibacterial SPI-based material with high mechanical strength by integrating polyethyleneimine (PEI) and metal ions (Cu(II) or Zn(II)). The tensile strengths of the SPI/PEI-Cu-0.750 and SPI/PEI-Zn-0.750 films reach up to 10.46 ± 0.50 and 9.06 ± 0.62 MPa, which is 367.06 and 306.28% strength increase compared to that of neat SPI film, respectively. Due to abundant non-covalent bonds and low glass transition temperature of the network, both SPI/PEI-Cu and SPI/PEI-Zn films exhibit a satisfactory self-healing behavior even at room temperature. Furthermore, SPI/PEI-Cu and SPI/PEI-Zn films demonstrate high bacterial resistance against Escherichia coli and Staphylococcus aureus. This facile strategy of establishing dynamic networks in a biomaterial with numerous excellent properties will enormously expand the scope of its applications, especially in the field of recyclable and durable materials.

Kinetics and Characteristics of Soybean Oil and Protein Extracted by AOT Reverse Micelle Technology

The mass transfer process of soybean oil extracted by AOT reverse micelle was determined. Meanwhile, the physicochemical properties of oil and structural properties of protein were also investigated by gas chromatography (GC), Fourier infrared spectrum (FTIR), and amino acid analyzer. The results indicated that the mass transfer model can be set up as 1+2(1-x)-3(1-x)2/3=0.248•exp⁡(-720.8/T)•t. The reaction probably belongs to internal diffusion. The oil extracted by AOT reverse micelle was in better quality according to physicochemical analysis. The soybean protein almost retained its original structure in AOT reverse micelle by FTIR and amino acid analysis. Therefore, AOT reverse micelle is an attractive procedure for extracting oil and protein simultaneously.

Milling solid proteins to enhance activity after melt-encapsulation

Polymeric systems for the immobilization and delivery of proteins have been extensively used for therapeutic and catalytic applications. While most devices have been created via solution based methods, hot melt extrusion (HME) has emerged as an alternative due to the high encapsulation efficiencies and solvent-free nature of the process. HME requires high temperatures and mechanical stresses that can result in protein aggregation and denaturation, but additives and chemical modifications have been explored to mitigate these effects. This study explores the use of solid-state ball milling to decrease protein particle size before encapsulation within poly(lactic-co-glycolic acid) (PLGA) via HME. The impact of milling on particle dispersion, retained enzymatic activity, secondary structure stability, and release was explored for lysozyme, glucose oxidase, and the virus-like particle derived from Qβ to fully understand the impact of milling on protein systems with different sizes and complexities. The results of this study describe the utility of milling to further increase the stability of protein/polymer systems prepared via HME.

Linking naturally and unnaturally spun silks through the forced reeling of Bombyx mori

The forced reeling of silkworms offers the potential to produce a spectrum of silk filaments, spun from natural silk dope and subjected to carefully controlled applied processing conditions. Here we demonstrate that the envelope of stress-strain properties for forced reeled silks can encompass both naturally spun cocoon silk and unnaturally processed artificial silk filaments. We use dynamic mechanical thermal analysis (DMTA) to quantify the structural properties of these silks. Using this well-established mechanical spectroscopic technique, we show high variation in the mechanical properties and the associated degree of disordered hydrogen-bonded structures in forced reeled silks. Furthermore, we show that this disorder can be manipulated by a range of processing conditions and even ameliorated under certain parameters, such as annealing under heat and mechanical load. We conclude that the powerful combination of forced reeling silk and DMTA has tied together native/natural and synthetic/unnatural extrusion spinning. The presented techniques therefore have the ability to define the potential of Bombyx-derived proteins for use in fibre-based applications and serve as a roadmap to improve fibre quality via post-processing.

Selective chemical modification of soy protein for a tough and applicable plant protein-based material

A tough, stable, and antimicrobial soy protein film is obtained from the slight chemical modification on the polypeptide chain, which broadens the application area of such a cheap, abundant and sustainable natural material.

Determination of phase behaviour in all protein blend materials with multivariate FTIR imaging technique

Multivariate FTIR imaging technique is introduced to analyse a silk fibroin/soy protein blend, which shows that the silk fibroin domains are dispersed in soy protein matrix.

Electricity from the silk cocoon membrane

Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management.

Determination of the domain structure of the 7S and 11S globulins from soy proteins by XRD and FTIR

BACKGROUND

The 7S and 11S fractions from soybean proteins have interesting high nutritional and excellent functional properties. The aim of this research was to improve the functional properties of soy proteins by studying the effect of bis(2-ethylhexyl) sodium sulfosuccinate (AOT) reverse micelles on the conformation of the 7S and 11S globulins using Fourier transform infrared and X-ray diffraction spectroscopy.

RESULTS

Fourier transform infrared revealed that the intensity of the 7S and 11S globulin bands from AOT reverse micelle extraction at 1600-1700, 1480-1575, 1220-1300, 3330, 1448 and 1395 cm(-1) was higher than from aqueous buffer. X-ray diffraction data showed that the intensities of 7S globulin using two extraction methods at 2θ about 10° were significantly different (P < 0.05), about 22° slightly increased. The intensities of 11S globulin at 2θ about 10° and 22° were similar. The average distance between particles (dhkl ) for 7S globulin with aqueous buffer extraction at 2θ about 10° was greater than AOT reverse micelle extraction.

CONCLUSION

This study showed the potential of reverse micelles as a protocol for extracting the 7S and 11S globulins for analytical purposes. The results represent a new avenue for determining the structures of the 7S and 11S globulins.