Harnessing light: Synthesis, mechanisms, and pre-clinical biomedical applications of stimuli-responsive multiscale composites

Smart multiscale composites with stimuli-responsive versatility have significantly advanced the field of biomedical science by providing precise spatiotemporal control over modulating, diagnostic, and therapeutic functions. Light-responsive composite (LRC) systems, in particular, present unique advantages owing to their non-invasive nature, bio-favorable features, high accuracy, and capacity for real-time modulation. As a safe external stimulus, light can be manipulated to modify the chemical and biochemical behavior of material composites, thus offering considerable potential within the domain of photo-pharmacology. Consequently, researchers have developed multifunctional platforms for a broad spectrum of biomedical applications, ranging from bioimaging to wound healing, by integrating light-responsive components, such as photoinitiators, luminescent/plasmonic nanoparticles, polymers, hydrogels, and hybrid scaffolds, into composite systems. Despite the substantial proliferation of original research articles in recent years, there exists a notable deficiency in comprehensive frameworks or strategic blueprints that encompass these advancements. This timely review seeks to elucidate recent progress in the realm of LRC materials, with a focus on their design principles, activation mechanisms, and emerging applications within biomedicine. Herein, a variety of multidimensional composites are discussed, including two-/one-dimensional tissue engineering/phototherapeutic platforms and zero-dimensional molecular imaging agents. Nonetheless, the exploration of these varied light-responsive materials is articulated in a manner accessible to both general and expert audiences, ensuring clarity and comprehension of complex mechanisms. Furthermore, this review addresses the considerations and specific challenges pertinent to toxicity, reproducibility/scalability, as well as clinical transitions, contributing to a deeper understanding of the potential of these innovative material composites in practical applications.