Adjacent cationic–aromatic sequences yield strong electrostatic adhesion of hydrogels in seawater

Abstract

Electrostatic interaction is strong but usually diminishes in high ionic-strength environments. Biosystems can use this interaction through adjacent cationic–aromatic amino acids sequence of proteins even in a saline medium. Application of such specific sequence to the development of cationic polymer materials adhesive to negatively charged surfaces in saline environments is challenging due to the difficulty in controlling the copolymer sequences. Here, we discover that copolymers with adjacent cation–aromatic sequences can be synthesized through cation–π complex-aided free-radical polymerization. Sequence controlled hydrogels from diverse cation/aromatic monomers exhibit fast, strong but reversible adhesion to negatively charged surfaces in seawater. Aromatics on copolymers are found to enhance the electrostatic interactions of their adjacent cationic residues to the counter surfaces, even in a high ionic-strength medium that screens the electrostatic interaction for common polyelectrolytes. This work opens a pathway to develop adhesives using saline water.

Structure and sequence features of mussel adhesive protein lead to its salt-tolerant adhesion ability

“…As indicated in a recent work about mussel-mimic peptide and the ones with Dopa replaced by Tyr and Phe ( 31 ), cation-π interaction occurs in all these three peptides: Lys and aromatic residues tend to form cation-π interactions in the peptides enriched with these two types of residues. Besides, a recent work on the adsorption behavior of copolymer also found that aromatic residues enhance electrostatic interaction of their adjacent cationic residues with the surface ( 67 ). In addition, as a small amount of Dopa or Tyr (~10%) is conjugated to poly-lysine, its adsorption ability is enhanced to a similar extent ( 28 , 68 ).…”

Particle packing into loose networks for tough and sticky composite gels

“…Because of a lower cross-linking ratio, current tough composite gels have many dangling chains on the surface and show sticky properties 28 – 30 . In a general hydrogel, in order to exhibit such properties, it is necessary to create an extremely low degree of crosslinking.…”

Covalently Functionalized Carbon Nano-Onions Integrated Gelatin Methacryloyl Nanocomposite Hydrogel Containing γ-Cyclodextrin as Drug Carrier for High-Performance pH-Triggered Drug Release

“…Due to their three-dimensional porous network, flexibility, and high water content, hydrogels are attractive biomaterial scaffolds for drug delivery, [ 1 , 2 , 3 ] tissue engineering, [ 4 ] vaccines, [ 5 , 6 ] and biosensors [ 7 ]. Several crosslinking strategies including chemical conjugations, [ 8 , 9 ] physical interactions, [ 10 , 11 ] and polymerizations [ 12 , 13 ] have been formulated for hydrogel synthesis. However, the fabrication of next-generation hydrogels with amended functional and structural recapitulations of damaged organs remains a challenge.…”