Processing and characterization of biodegradable soy plastics: Effects of crosslinking with glyoxal and thermal treatment

Abstract

Processing and modification routes to produce and to improve properties of biodegradable plastics from soy isolate were studied. Soy isolate, acid-treated and crosslinked soy were subsequently compounded, extruded, and injection molded. Acetic acid and glyoxal were examined concerning their suitability for acid treating and crosslinking of soy, and their effect on the final properties of the obtained materials. Heat treatment was also used as a possible methodology to crosslink the protein structure. The molded specimens were tested in terms of their tensile properties and solubility at different pHs, and were also evaluated for the degree of crosslinking and molecular weight distributions. The obtained plastics were rigid and brittle with stiffness ranging from 1436 MPa for soy, to 1229 MPa for glyoxal crosslinked soy, up to 2698 MPa for heat-treated soy. The differences in stiffness were discussed in terms of the crosslinking efficiency and spatial distribution. The solubility profiles were studied as a function of the pH of the immersion solutions and the crosslinking degree of each material. A reduction in protein solubility with decreasing pH was observed, with a minimum between pH 4 and 5 and a resolubilization of the protein at pHs lower than pH 4 and greater than 8. Higher levels of crosslinking resulted in a decrease of the solubility and an aggregation of the protein molecules. The soy plastics proved to be very versatile materials with potential to be used in applications where quite demanding performances are expected, such as in the biomedical field.

Cross-linked soy protein as material for biodegradable films: Synthesis, characterization and biodegradation

“…The e-amino group of lysine was considered the primary reactive site between proteins and cross-linkers (Nayudamma et al, 1961). The cross-linkers most extensively used for proteins are aldehydic compounds such as glutaraldehyde (Park et al, 2000;Bigi et al, 2001;Marquié, 2001), formaldehyde (Marquié, 2001) and glyoxal (Vaz, 2005), and epoxy (Patil et al, 2000) and phenolic compounds (Strauss and Gibson, 2004). However, the cytotoxicity of these compounds restricts their use for food covering.…”

Glutaraldehyde and glyoxal cross-linked chitosan microspheres for controlled delivery of centchroman

“…[26][27][28] Glutaraldehyde cross-linked chitosan microspheres have shown dynamic storage properties, 16 ion adsorption, 29,30 and immobilization of enzyme 30 and systems for controlled drug delivery. 31,32 Recently other cross-linkers such as genepin [33][34][35] and glyoxal [36][37][38] and other polymers 37 have been examined for their possible applications in the biomedical field, but few studies are reported in which glyoxal is used as the cross-linker in controlled delivery systems. 39 Therefore, in the present investigation, cross-linked chitosan microspheres were prepared at different concentrations of glyoxal and glutaraldehyde using chitosan with different DDAs.…”

pH‐sensitive alginate/soy protein microspheres as drug transporter

“…The possible benefits of soy protein include lowering cholesterol, anticarcinogenic effects of Bowman-Birk (BBI), and protective effects against obesity, diabetes, irritants of the digestive tract, bone, and kidney diseases. 20 On the basis of the bioactivity of soy protein, the soy protein plastics prepared by melt-processing 21 and further modification of chemical crosslinking 22 showed a great potential applications as tissue engineering scaffold 23 and drug-delivery system. 22 Additionally, the soy protein-based membrane was also used as drug carrier and wound dressing material.…”

“…20 On the basis of the bioactivity of soy protein, the soy protein plastics prepared by melt-processing 21 and further modification of chemical crosslinking 22 showed a great potential applications as tissue engineering scaffold 23 and drug-delivery system. 22 Additionally, the soy protein-based membrane was also used as drug carrier and wound dressing material. 24 To further improve the biofunction and properties, the blending with other biocompatible polymers, such as chitin 25 and chitosan, 26 cellulose, 27 and poly(ethylene glycol), 28 was attempted, and especially produced a new form material of hydrogel for drug delivery.…”