Tannin‐Tethered Gelatin Hydrogels with Considerable Self‐Healing and Adhesive Performances

Abstract

wearable devices, [4] soft electronics, [5,6] battery binders, [7][8][9] etc. Among these versatile materials, self-healing hydrogels, which can recover their original properties through autonomous healing after suffering from damages, exhibit an enormous potential in the fields of wound closure, [10,11] scaffolds for tissue engineering, [12,13] drug/cell delivery devices, [14][15][16] and so on.In nature, marine mussels can tightly attach to almost all surfaces by secreting mussel adhesive proteins (MAPs). [17] In addition, the adhesion property of MAPs is attributed to the presence of a special catechol-containing amino acid compound, 3,4-dihydroxyphenylalanine (DOPA). [18] The catechol groups of DOPA are easy oxidized to quinones in alkaline condition [1] and subsequently react with nucleophiles such as amines and thiols to form the 3D net structure of hydrogel via Schiff's base and Michael addition reactions. [19] Additionally, the catechol moieties endow DOPA with the capability to complex with various metal ions in order to produce coordination-crosslinked hydrogels. Owing to the versatility of DOPA, it has been coupled through various reactions to numerous macromolecules, including chitosan, [20] gelatin, [19] and polyethylene glycol (PEG). [21] This has allowed to fabricate mussel-inspired materials with self-healing and adhesive properties. The high price and potential neurotransmission effect of DOPA limit its commercial applications, however, and consequently the search of alternatives to DOPA is necessary. [22] Tannic acid (TA), a plant-derived polyphenolic compound, consists of a glucose core and ester-linked peripheral gallol groups (three adjacent hydroxyls attached to benzene). [23] With these functional groups, TA is capable to precipitate proteins (collagen and gelatin) by multi-point hydrogen bond and hydrophobic interactions. [24] The two adjacent phenolic hydroxyls of gallols in TA can also chelate metal ions (e.g., Fe 3+ , Al 3+ , Cr 3+ ) in the form of oxygen anion to form stable pentacyclic complexes. Although the third phenol hydroxyl is not involved in the formation of these pentacyclic structures, it can encourage the dissociation of the other two adjacent OH groups and accelerate the coordination reaction promoting its stability. [25] In addition, TA presents a good antioxidant capacity. The gallols of TA are oxidized to form quinones that further undergo nucleophilic Hydrogels Hydrogels, especially the ones with self-recovery and adhesive performances, have attracted more and more attention owing to their wide practical potential in the biomedical field involving cell delivery, wound filling, and tissue engineering. Tannic acid (TA), a nature-derived gallol-rich polyphenol, exhibits not only unique chelating properties with transition metal cations but also desirable anti-oxidation properties and strong bonding capability to proteins and gelatin. Thus, taking advantage of the versatility of TA, a one-pot method is proposed herein to produce TA-modified gelatin hydrogels with the aid ...

Liquid Bandage Harvests Robust Adhesive, Hemostatic, and Antibacterial Performances as a First‐Aid Tissue Adhesive

“…The diagram is helpful to analyze comprehensive properties of existing hydrogel‐based tissue adhesives and provide design guidelines in hydrogel material selection for developing new tissue adhesives. [ 11,13,20,27–29,53–55,58,60–67 ]…”

Tailoring Gelation Mechanisms for Advanced Hydrogel Applications

“…Michael addition [15,70,71] Thiol-ene addition [16,68,69] Diels-Alder [4 + 2 ] cycloaddition [17,[59][60][61] Inverse-electron demand Diels-Alder cycloaddition [2,[62][63][64][65][66] Disulphide bond formation [18] Hydrazone bond formation [19] -Free-radical polymerization [137][138][139][140][141][142][143] -Polyphenol-based reactions [95][96][97][98][99][100][101] Reactions between polymer chains and nanoparticles -Thiol-ene addition [20,21] -Free-radical polymerization [22] -EDC coupling [23] -Coordinate covalent bond formation [84] Electrostatic interactions Ion-polymer interactions [24][25][26][27][28][29] Polymer-polymer interactions [31,32] Other noncovalent interactions Polymer-polymer interactions [33,…”

“…Catechol-functionalized -Poly(p-phenylene oxide)/PEG-based hydrogels [96] -Gelatin-based hydrogels [97] -Mussel adhesive protein hydrogels [98] Pyrogallol-functionalized -Gelatin-based hydrogels [100] -HA-based hydrogels [101] Enzyme addition…”

“…[99] Another functional group that enables oxidationmediated crosslinking is pyrogallol. HA [100] or gelatin [101] have been conjugated with pyrogallol and shown to form hydrogels following the addition of sodium periodate.…”

Self‐Detecting and Self‐Healing Reinforce Elastomer Doped with Aggregation‐Induced Emission Molecules

“…Self-healing and stimuli-responsive polymeric elastomers have attracted much attention because they exhibit wide potential applications in soft actuators, [1,2] smart sensors, [3,4] and flexible electronics. [5,6] The current self-healing elastomers mainly contain hydrogels, [7,8] natural or synthetic rubbers, [9,10] polyureathanes, [11][12][13] fluorocarbon elastomers, [14][15][16] thermoplastic polymers, [17] and poly(dimethylsiloxane) (PDMS), [12,18,19] in which PDMS is a highly versatile elastomer because of its tunable mechanical strength, high chemical stability, and inherent flexibility at broad temperature ranges. [20] Recently, much work have been endeavored to develop PDMS elastomers with self-healing and robust mechanical properties.…”