Novel Biodegradable Poly(1,4-dioxan-2-one) Grafted Soy Protein Copolymer: Synthesis and Characterization

A biodegradable soy protein isolate-based waterborne polyurethane composite sponge for implantable tissue engineering

A biodegradable soy protein isolate-based waterborne polyurethane composite sponge (SWPU) was prepared from soy protein isolate (SPI) and polyurethane prepolymer (PUP) by a process involving chemical reaction and freeze-drying. Effects of SPI content (0, 10%, 30%, 50%, 70%) on the micro-structure and physical properties of the composite sponges were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results showed that the reaction between -NCO of PUP and -NH₂ of SPI formed porous SPI-based WPU composite sponges. The results of the water absorption ratio measurement, solvent resistance measurement and compressive testing showed that water absorption, hydrophilicity, and tensile strength in the dry state of the composite sponges increased with the increase of SPI content. Especially, the tensile strength ranged from 0.3 MPa to 5.5 MPa with the increase in SPI content. The cytocompatibility and biodegradability of the composite sponges were evaluated by in vitro cell culture and in vivo implantation experiments. The results indicated that a certain SPI content in the sponges could promote the adhesion, growth, and proliferation of cells, enhance the cytocompatibility and accelerate the degradation speed of composite sponges. During the in vivo implanting period within 9 months, SWPU-50 sponge containing 50% of SPI brought out the lowest activated inflammatory reaction, most newly-regenerated blood capillaries, and best histocompatibility. All results indicated that SWPU-50 composite sponges had greatest potential for tissue engineering.

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.