The ability to safely and quickly destroy very specific types of cell in a living body will be a core technology for the new medicine of the next few decades. There's no shortage of potential targets in the aging body: cancer, senescent cells pumping out damaging biochemicals, malconfigured immune cells, and so forth. Researchers are making good progress on this technology base: "Now, we're engineering sophisticated nanostructures to elude the body's natural defenses, locate tumors and other diseased cells, and release a payload of therapeutics, contrasting agents, or both over a controlled period. ... Getting intravenous agents to their intended targets is no easy task. ... To overcome this problem, we hypothesized and developed a multifunctional [multistage delivery system (MDS)] comprising stage 1 mesoporous particles loaded with one or more types of stage 2 nanoparticles, which can in turn carry either active agents or higher-stage particles. We have demonstrated the loading, controlled release and simultaneous in vitro delivery of quantum-dots and carbon nanotubes to human vascular cells. ... Once on site, the molecules can be released in a controlled way and then the MDS will degrade in 24 to 48 hours, be transformed into orthosilicic acid and leave no trace in the body." The medicine of tomorrow, arriving soon.