Injectable nanorobots for precision cancer therapy: motion-enhanced drug delivery

Cancer remains a major global health challenge, demanding innovative strategies to overcome the limitations of conventional therapies. While nanoparticle-based drug delivery systems show potential, their clinical translation is hindered by low targeting efficiency and insufficient tissue penetration. Injectable nanorobots, capable of autonomous movement driven by external fields or endogenous fuels, offer a transformative technology to enhance drug delivery precision. Following the brief discussion of propulsion mechanisms, design and fabrication of injectable nanorobots, this review provides a comprehensive summary of injectable nanorobots designed for precision cancer therapy. It focuses on their dynamic performance across six critical stages: circulation, targeting, penetration, internalization, release, and treatment (CTPIRT process). Compared to passive nanoparticles, self-propelled nanorobots demonstrate superior tumor accumulation, deeper tissue penetration, and enhanced cellular internalization. Furthermore, they can substantially amplify therapeutic efficacy by enabling stimulus-responsive drug release and integrating diverse treatment strategies. Finally, this review delves into the unresolved challenges in scalable fabrication, biosafety, and clinical translation of injectable nanorobots. Interdisciplinary strategies are proposed to help bridge the gap between laboratory research and clinical translation. Together, this review highlights injectable nanorobots as a paradigm shift in precision drug delivery, promising a path toward surmounting the long-standing barriers in cancer therapy.