Investigation of the Adhesion Mechanism and Stability Improvement of Plant-Based Connective Tissue Mimics Prepared via Enzymatic Reaction.

Abstract

In this study, a soy protein isolate-polysaccharide hydrogel was employed to simulate connective tissue, and the regulatory mechanism of transglutaminase (TG) addition on its crosslinking structure, micromorphology, and adhesion stability was systematically investigated. The crosslinking degree and fluorescence spectral results demonstrated that TG enhanced intermolecular interactions, including both protein-protein and protein-polysaccharide interactions. However, excessively high enzyme concentrations (SPI:TG ratios of 2:3 or lower) inhibited crosslinking, possibly due to steric hindrance. The crosslinking degree reached a maximum of 21.55% at 0.75% TG, while the mean particle size decreased to a minimum of 50.28 nm at an SPI:TG ratio of 1:1 (1.00% TG), where a compact gel network was formed. Fourier transform infrared spectroscopy confirmed that hydrogen bonds and amide bonds synergistically stabilized the network structure, while scanning electron microscopy revealed a dense and uniform honeycomb-like porous morphology. The 1:1 group exhibited the highest apparent viscosity and the smallest difference in hardness between two compression cycles (2795.0 g-2469 g), demonstrating balanced toughness and adhesion stability. After assembly with textured protein, the 1% TG-crosslinked mimic maintained interfacial bonding after two freeze-thaw cycles and pan-frying, whereas the control without TG fractured at the interface. This study provides a theoretical basis for the construction of the plant-based connective tissue mimic with high stability.