Mussel-Mimicking Sustainable Protein-Based Biogel, a Potential Alternative to Chemical Adhesives

Nowadays, the majority of widely utilized adhesives are sourced from unsustainable petroleum-based materials, with their production and application inevitably releasing toxic chemicals. In recent years, despite ongoing attempts to develop novel, sustainable, and eco-friendly biobased adhesives, this shift has often been accompanied by significantly declined performance, increased manufacturing complexity, and substantially high costs. Herein, designed according to the adhesion mechanism of mussels, we reported an eco-friendly protein-based adhesive gel (named PPD) with superior adhesion and antibacterial properties. It is formulated from naturally sourced polyglutamic acid (PGA), ε-polylysine (ε-PLL), and dihydrocaffeic acid (DHCA) via simple steps under mild conditions. The core polymerization process relied on reversible electrostatic interaction, enabling it to have injectable properties. After solidification, PPD exhibited superior adhesion on various surfaces, achieving a maximum adhesion strength of 13.53 MPa. Following 1 h of water immersion, adhesion strength could retain 6.04 MPa. Meanwhile, PPD demonstrated a significant antibacterial activity against Escherichia coli and Staphylococcus aureus, due to the contact antibacterial ability of cationic ε-polylysine and the H₂O₂ generation from the continuous oxidation of catechol. Additionally, good biocompatibility favors its promising potential for wide applications, especially in the medical field.