Tailoring Gelation Mechanisms for Advanced Hydrogel Applications

Hydrogels are one of the most commonly explored classes of biomaterials. Their chemical and structural versatility has enabled their use across a wide range of applications, including tissue engineering, drug delivery, and cell culture. Hydrogels form upon a sol–gel transition, which can be elicited by different triggers designed to enable precise control over hydrogelation kinetics and hydrogel structure. The chosen hydrogelation trigger and chemistry can have a profound effect on the success of the targeted application. In this Progress Report, a critical overview of recent advances in hydrogel design is presented, with a focus on the available strategies used to trigger the formation of hydrogel networks (e.g., temperature, light, ultrasound). These triggers are presented within a new classification system, and their suitability for six key hydrogel-based applications is assessed. This Progress Report is intended to guide trigger selection for new hydrogel applications and inspire the rational design of new hydrogelation trigger mechanisms.