Exploiting Redox-Complementary Peptide/Polyoxometalate Coacervates for Spontaneously Curing into Antimicrobial Adhesives

Recently, there has been a wave of reports on the fabrication of peptide-based underwater adhesives with the aim of understanding the adhesion mechanism of marine sessile organisms or creating new biomaterials beyond nature. However, the poor shear adhesion performance of the current peptide adhesives has largely hindered their applications. Herein, we proposed to sequentially perform the interfacial adhesion and bulk cohesion of peptide-based underwater adhesives using two redox-complementary peptide/polyoxometalate (POM) coacervates. The oxidative coacervates were prepared by mixing oxidative H5PMo10V2O40 and cationic peptides in an aqueous solution. The reductive coacervates consisted of K5BW12O40 and cysteine-containing reductive peptides. Each of the individual coacervate has well-defined spreading capacity to achieve fast interfacial attachment and adhesion, but their cohesion is poor. However, after mixing the two redox-complementary coacervates at the target surface, effective adhesion and spontaneous curing were observed. We identified that the spontaneous curing resulted from the H5PMo10V2O40-regulated oxidization of cysteine-containing peptides. The formed intermolecular disulfide bonds improved the cross-linking density of the dual-peptide/POM coacervates, giving rise to the enhanced bulk cohesion and mechanical strength. More importantly, the resultant adhesives showcased excellent bioactivity to selectively suppress the growth of Gram-positive bacteria due to the presence of the polyoxometalates. This work raises further potential in the creation of biomimetic adhesives through the orchestrating of covalent and noncovalent interactions in a sequential fashion.