Renal clearable inorganic nanoparticles: a new frontier of bionanotechnology

While inorganic nanoparticles (NPs) with tunable and diverse material properties open up unprecedented opportunities for novel biomedical technologies, translating these NPs into clinical practices has been severely hampered by the toxicity induced by their nonspecific accumulation in healthy tissues/organs. In the past few years, the emergence of renal clearable inorganic NPs has made it possible to address this long-term challenge. This review summarizes size, shape, surface chemistry and biodegradation considerations in the design of renal clearable inorganic NPs and their strengths over conventional non-renal clearable NPs and small-molecule contrast agents in tumor targeting. Finally, some materials chemistry challenges in the development of renal clearable inorganic NPs and their biomedical implications beyond tumor targeting are discussed.