Technology: general issues bismuth oxide chemotherapy drug-eluting stent gold nanoparticles hydrogel immobilization iron oxide nanoparticles janus particles magnetic nanoparticles magnetite nanoparticles mesoporous zinc oxide metal nanoparticles nanoparticles nanoshells (hollow spheres) pH-triggered drug release photodynamic therapy photothermal therapy pickering emulsion polyHEMA polymer coating protein radiopacity reactive oxygen species self-assembly silver nanoparticles sonodynamic therapy theragnostic titanium dioxide nanoparticles zinc nanoparticles