Rational Design of Mussel-Inspired Hydrogels with Dynamic Catecholato-Metal Coordination Bonds

Nature has often been the main source of inspiration for designing smart functional materials. As an example, mussels can attach to almost any wet surfaces, for example, wood, rocks, metal, etc., due to the presence of catechols containing amino acid 3,4-dihydroxyphenyl-l-alanine (DOPA). Fabrication of mussel-inspired hydrogels using dynamic catecholato-metal coordination bonds has recently been in the limelight because of the hydrogels' ease of gelation, interesting self-healing, self-recovery, adhesiveness, and pH-responsiveness, as well as shear-thinning and mechanical properties. Mussel inspired hydrogels take advantage of catechols, for example, DOPA in the blue mussel, to undergo catecholatometal gelation through coordination chemistry. This review explores the latest developments in the fabrication of such hydrogels using catecholato-metal coordination bonds, and discusses their potential applications in sensors, flexible electronics, tissue engineering, and wound dressing. Moreover, current challenges and prospects of such hydrogels are discussed. The main focus of this paper is on providing a deeper understanding of this growing field in terms of chemistry, physics, and associated properties.