Synthesis, characterization and degradation of biodegradable thermoplastic elastomers from poly(ester urethane)s and renewable soy protein isolate biopolymer

Characterization of Bio-Inspired Electro-Conductive Soy Protein Films

Protein-based conductive materials are gaining attention as alternative components of electronic devices for value-added applications. In this regard, soy protein isolate (SPI) was processed by extrusion in order to obtain SPI pellets, subsequently molded into SPI films by hot pressing, resulting in homogeneous and transparent films, as shown by scanning electron microscopy and UV-vis spectroscopy analyses, respectively. During processing, SPI denatured and refolded through intermolecular interactions with glycerol, causing a major exposition of tryptophan residues and fluorescence emission, affecting charge distribution and electron transport properties. Regarding electrical conductivity, the value found (9.889 × 10⁻⁴ S/m) is characteristic of electrical semiconductors, such as silicon, and higher than that found for other natural polymers. Additionally, the behavior of the films in contact with water was analyzed, indicating a controlled swelling and a hydrolytic surface, which is of great relevance for cell adhesion and spreading. In fact, cytotoxicity studies showed that the developed SPI films were biocompatible, according to the guidelines for the biological evaluation of medical devices. Therefore, these SPI films are uniquely suited as bioelectronics because they conduct both ionic and electronic currents, which is not accessible for the traditional metallic conductors.

Fabrication, properties and applications of soy-protein-based materials: A review

The environmental crisis caused by the use of petroleum-based nondegradable polymers and the impending petroleum finite resources have directly threatened human being's sustainable development. Therefore, ecofriendly polymers based on natural renewable resources are attracting more and more attention. As the byproducts of soy oil industries, soy protein, is regarded as a viable alternative for petroleum-based polymeric products. In order to improve the physical properties, especially the mechanical properties and water resistance that limit their extensive applications, different modifications were adopted. Among these efforts, incorporating nanoparticles and blending with other polymers are proved to be effective ways. The properties of the resulting materials are highly dependent on the processing methods, nature of the components, dispersion status and the compatibility. This review intends to provide a clear overview on preparation, properties, and applications of soy-protein-based materials. These biodegradable materials will find more and more potential applications in biodegradable foams, edible films, packaging materials, biomedical materials, etc.

Mechanical and water-resistant properties of rice straw fiberboard bonded with chemically-modified soy protein adhesive

In this work, rice straw and soy protein were used to make fiberboard which may replace wood fiberboard. Soy protein isolates (SPI) were modified by epoxidized oleic acid to improve the soy protein adhesive properties such as adhesion strength and water resistance. The effects of NaOH content, the addition of modified-SPI adhesives and fiberboard density on the mechanical and water-resistant properties of the rice straw fiberboards were investigated. FTIR and XRD results of modified SPI indicated the epoxidized oleic acid and soy protein reacted with each other. FTIR and SEM images of rice straw fibers showed that NaOH solution removed the wax layer through chemical etching. The results of investigating mechanical properties and water absorption illustrate that when the soy protein-based adhesives content and density and the hot pressing temperature and pressure of fiberboard are 12%, 0.8 g cm⁻³, 140 °C and 6 MPa, respectively, the panels have optimal mechanical and water-resistant performances. Moreover, the panels meet the requirements of chinese medium density fiberboard (MDF) Standard of GB/T 11718-2009. Since biological raw materials are recyclable and biomass, the fiberboard bonded with modified soy protein adhesive has no toxicity and is easily biodegradable. In addition, the rice straw burned to produce haze has been preferably utilized.

In this work, rice straw and soy protein were used to make fiberboard which may replace wood fiberboard.

Polyhydroxyalkanoate/carbon nanotube nanocomposites: flexible electrically conducting elastomers for neural applications

Aim: Medium chain length-polyhydroxyalkanoate/multi-walled carbon nanotube (MWCNTs) nanocomposites with a range of mechanical and electrochemical properties were fabricated via assisted dispersion and solvent casting, and their suitability as neural interface biomaterials was investigated. Materials & methods: Mechanical and electrical properties of medium chain length-polyhydroxyalkanoate/MWCNTs nanocomposite films were evaluated by tensile test and electrical impedance spectroscopy, respectively. Primary rat mesencephalic cells were seeded on the composites and quantitative immunostaining of relevant neural biomarkers, and electrical stimulation studies were performed. Results: Incorporation of MWCNTs to the polymeric matrix modulated the mechanical and electrical properties of resulting composites, and promoted differential cell viability, morphology and function as a function of MWCNT concentration. Conclusion: This study demonstrates the feasibility of a green thermoplastic MWCNTs nanocomposite for potential use in neural interfacing applications.