Adhesive Coacervates Driven by Hydrogen‐Bonding Interaction

Abstract

Coacervate is the concentrated polymer-rich liquid phase that originates from the spontaneous liquid-liquid phase separation of a colloidal system, which has been considered as "the origin of life" for its high resemblance with protoplasm, [1] precellular systems, [2] and membrane-free organelles. [3] Coacervation also plays a critical role in constructing biological tissues (e.g., forming extracellular matrices via assembling elastin with tropoelastin) [4] and developing gradient properties in materials (e.g., squid beak possessing 200 times stiffness gradient), [5] with important applications in various industrial, biological, and medical fields. [6] Coacervates are extensively employed by sessile organisms such as sandcastle worm and mussel to realize strong adhesion under turbulent seawater, [7] which inspires potential applications of coacervates as implanted biomaterials like tissue glues, wound dressings, and drug carriers. Coacervation plays a critical role in numerous biological activities such as constructing biological tissues and achieving robust wet adhesion of marine sessile organisms, which conventionally occurs when oppositely charged polyelectrolytes are mixed in aqueous solutions driven by electrostatic attraction. Here, a novel type of adhesive coacervate is reported, driven by hydrogen-bonding interactions, readily formed by mixing silicotungstic acid and nonionic polyethylene glycol in water, providing a new approach for developing coacervates from nonionic systems. The as-prepared coacervate is easily paintable underwater, show strong wet adhesion to diverse substrates, and has been successfully applied as a hemostatic agent to treat organ injuries without displaying hemolytic activity, while with inherent antimicrobial properties thus avoiding inflammations and infections due to microorganism accumulation. This work demonstrates that coacervation can occur in salt-free environments via non-electrostatic interactions, providing a new platform for engineering multifunctional coacervate materials as tissue glues, wound dressings and membrane-free cell systems.

Genetically Engineered Polypeptide Adhesive Coacervates for Surgical Applications

“…As a result, the solution became turbid and after centrifugation a viscous SUP‐surfactant complex was obtained. This liquid‐liquid phase separation behavior leads to the formation of protein‐surfactant coacervates [25, 26] . The water content was ≈30 % (w/w) in the SUP‐surfactant complexes as determined by thermogravimetric analysis (TGA) (Figure S3).…”

“…This liquid‐liquid phase separation behavior leads to the formation of protein‐surfactant coacervates. [ 25 , 26 ] The water content was ≈30 % (w/w) in the SUP‐surfactant complexes as determined by thermogravimetric analysis (TGA) (Figure S3). After lyophilizing for ≈30 min, ≈14 % of water remained in the coacervate (Figure S4), resulting in the formation of the protein‐based adhesive (Figure 1 C ).…”

Genetically Engineered Polypeptide Adhesive Coacervates for Surgical Applications

“…This liquid-liquid phase separation behavior leads to the formation of proteinsurfactant coacervates. [25,26] Thew ater content was % 30 % (w/w) in the SUP-surfactant complexes as determined by thermogravimetric analysis (TGA) (Figure S3). After lyophilizing for % 30 min, % 14 %o fw ater remained in the coacervate (Figure S4), resulting in the formation of the proteinbased adhesive (Figure 1C).…”

Polymer Pressure‐Sensitive Adhesive with A Temperature‐Insensitive Loss Factor Operating Under Water and Oil

“…The wetting environment may lead to the failure of pressure‐sensitive adhesion because the hydration of the polymers or swelling of the adhesive will hinder the formation of the interactions between the adhesive and target surface; therefore, strong adhesion is usually achieved in the dry state. [ 1 ] Recently, increasing studies have been focused on the engineering underwater adhesives and different methods such as surface drainage architecture design, [ 2–4 ] catechol chemistry, [ 5–7 ] hydrophobic adjustment, [ 8,9 ] water‐displacing [ 10,11 ] was proposed. However, many of the adhesives are only used at room temperature and their underwater adhesion performance under extreme temperature are unknown or unexplored.…”

“…surface; therefore, strong adhesion is usually achieved in the dry state. [1] Recently, increasing studies have been focused on the engineering underwater adhesives and different methods such as surface drainage architecture design, [2][3][4] catechol chemistry, [5][6][7] hydrophobic adjustment, [8,9] water-displacing [10,11] was proposed. However, many of the adhesives are only used at room temperature and their underwater adhesion performance under extreme temperature are unknown or unexplored.…”