Renal Clearable Nanoparticles: An expanding horizon for improving biomedical imaging and cancer therapy

Abstract Renal excretion mechanisms, such as glomerular and tubular excretion processes, are an important part of renal function and provide general information about effective excretion of substances. Nanotechnology has significant applications in many biological and medical fields. In medical applications, especially tumor diagnosis and treatment, the significant point is that nanoparticle drugs should be nontoxic with excellent biodegradability and less physiologically interfere. Nanomaterial with rapid and complete renal clearance is substantially biocompatible and nontoxic. Glomerulus can filter NP with a hydrodynamic diameter of less than 6 nm. In contrast, nanoparticles with HDs greater than 8 nm cannot mainly pass through the kidney. By decreasing the nanomaterials' diameter under the limit value for kidney filtering (6 nm) and increasing their biological durability, approximately all nanostructures can be engineered to be applicable and nontoxic. Also, by adjusting the scale, charge, and structure of NPs, their transfer activities and reactions can be modified through the kidneys. In this article, the related mechanisms of kidney clearance, the effective factors to generate nontoxic and renal clearable nanoparticles, and their applications in biomedical imaging, tumor diagnosis and treatment are discussed.