Smart transformable nanoparticles for enhanced tumor theranostics

The physical morphologies of nanoparticles, especially size and shape, always significantly influence their biological behaviors. In the past, nanoparticles with constant physical morphologies have been widely investigated and applied in tumor theranostics. With the increased in-depth knowledge of tumors and physiological microenvironments, nanoparticles are required to self-adjust their physical morphologies during their circulation in varying physiological microenvironments and when reaching tumor site that possess distinct microenvironments. Therefore, smart transformable nanomaterials, which can alter their morphologies under different physiological conditions, show great potential in advanced tumor theranostics. This review summarizes the influence of nanoparticles' physical morphologies on their biological behaviors under different physiological conditions, highlights the designs of transformable nanoparticles serving as a guideline for their construction, intensively discusses the recent biomedical applications of these smart transformable nanoparticles for tumor theranostics, and also proposes future challenges and perspectives in the development of smart transformable nanoparticles for tumor theranostics.