A mechanistic understanding to photophysical phenomenon in development of near-infrared (NIR) responsive hydrogels: Advancements in precision drug delivery

Abstract

Near-Infrared (NIR)-responsive hydrogels have emerged as an advanced class of smart materials with significant potential for precise, spatiotemporally controlled drug delivery via external NIR light stimulation. These hydrogels leverage the unique attributes of NIR light, including deep tissue penetration and minimal damage to surrounding tissues, thus offering substantial advantages in biomedical applications. This review presents an in-depth analysis of the underlying mechanisms of NIR-responsive hydrogels, including photothermal effects, photochemical reactions, and phase transition processes, which facilitate the controlled release of therapeutic agents. Recent advances in the synthesis and functionalization of these hydrogels are explored, with a focus on their application in targeted drug delivery for cancer therapy, where localized heating enables site-specific drug release, minimizing off-target effects. Additional applications in wound healing, Cancer therapy and transdermal drug delivery are also reviewed, emphasizing the hydrogels' ability to deliver bioactive molecules such as growth factors or drugs in response to external stimuli. Despite their promising potential, several challenges hinder the clinical translation of NIR-responsive hydrogels, including concerns regarding the biocompatibility and long-term stability of nanomaterials, as well as the need for precise control over drug release kinetics. This review critically addresses these challenges and discusses emerging strategies to overcome them, providing insights into future directions for the field. Material innovations and advancements in nanotechnology are expected to play a pivotal role in enhancing the performance and clinical applicability of NIR-responsive hydrogels.