Absorption, distribution, metabolism, and excretion of nanocarriers in vivo and their influences.

As one of the most promising and effective delivery systems for targeted controlled-release drugs, nanocarriers (NCs) have been widely studied. Although the development of nanoparticle preparations is very prosperous, the safety and effectiveness of NCs are not guaranteed and cannot be precisely controlled due to the unclear processes of absorption, distribution, metabolism, and excretion (ADME), as well as the drug release mechanism of NCs in the body. Thus, the approval of NCs for clinical use is extremely rare. This paper reviews the research progress and challenges of using NCs in vivo based on a review of several hundred closely related publications. First, the ADME of NCs under different administration routes is summarized; second, the influences of the physical, chemical, and biosensitive properties, as well as targeted modifications of NCs on their disposal process, are systematically analyzed; third, the tracer technology related to the in vivo study of NCs is elaborated; and finally, the challenges and perspectives of nanoparticle research in vivo are introduced. This review may help readers to understand the current research progress and challenges of nanoparticles in vivo, as well as of tracing technology in nanoparticle research, to help researchers to design safer and more efficient NCs. Furthermore, this review may aid researchers in choosing or exploring more suitable tracing technologies to further advance the development of nanotechnology.