Microenvironment-responsive nanorobots for biomedical applications.

Conventional drug therapies face significant limitations in complex physiological environments, including poor targeting efficiency, passive diffusion mechanisms, and systemic toxicity. Inspired by the immune system, where immune cells are actively navigated by chemotactic gradients to reach infection sites, researchers have developed nanorobots capable of autonomous, microenvironment-responsive drug delivery. These nanorobots convert endogenous biochemical cues (e.g., pH, enzymes, reactive oxygen species) into directed motion and structure or shape changes, enabling deep tissue penetration and lesion-specific drug release. This review categorizes microenvironment-responsive nanorobots into three functional classes-locomotion, degradation, and deformation-based on their response behaviors to pathological signals. We critically analyze their design principles, biomedical applications in different diseases, and translational challenges. By bridging bioinspired strategies with engineered nanorobotics, this work provides a roadmap for next-generation precision therapeutics.