Effects of guar gum on adhesion properties of soybean protein isolate onto porcine bones

The aim of this study was to provide a basis for the preparation of medical adhesives from soybean protein sources. Effects of guar gum (GG) on the adhesion properties, microstructure and bond strength of soybean protein isolate (SPI) glues onto porcine bones were investigated. The results indicated that the tensile-bond strength of SPI adhesives first increased with an increase in GG concentration and later decreased after reaching a peak. The bond strength of 5% SPI adhesive was maximal with the addition of 0.5% GG, for which the strength was 2.8-fold higher than the control. GG addition significantly increased the zero-shear viscosity and hydrogen bonding, and changed the protein secondary structure of SPI adhesives with a decline in the α-helix content and an increase in the β-sheet content. X-ray diffraction analysis showed significant interactions between GG and SPI molecules and good miscibility of GG and SPI. The protein structure tended to loosen, and the adhesives formed an amorphous structure that favors the bonding between adhesives and bones. Taken together, GG addition caused an increase in the hydrogen bonding, density of protein aggregates and zero-shear viscosity of SPI adhesives, leading to a significant increase in the bond strength of SPI adhesives onto porcine bones.