A medical device comprising radiopaque water-dispersible metallic nanoparticles, wherein the nanoparticles are released from the medical device upon implantation of the device. The medical device of the present invention is sufficiently radiopaque for x-ray visualization during implantation, but loses its radiopacity after implantation to allow for subsequent visualization using more sensitive imaging modalities such as CT or MRI.
The nanoparticles are formed of a metallic material and have surface modifications that impart water-dispersibility to the nanoparticles. The nanoparticles may be any of the various types of radiopaque water-dispersible metallic nanoparticles that are known in the art. The nanoparticles may be adapted to facilitate clearance through renal filtration or biliary excretion. The nanoparticles may be adapted to reduce tissue accumulation and have reduced toxicity in the human body. The nanoparticles may be applied directly onto the medical device, e.g., as a coating, or be carried on the surface of or within a carrier coating on the medical device, or be dispersed within the pores of a porous layer or porous surface on the medical device. The medical device itself may be biodegradable and may have the nanoparticles embedded within the medical device itself or applied as or within a coating on the biodegradable medical device. The nanoparticles may be released by diffusion through the carrier coating, disruption of hydrogen bonds between the nanoparticles and the carrier coating, degradation of the nanoparticle coating, degradation of the carrier coating, diffusion of the nanoparticles from the medical device, or degradation of the medical device carrying the nanoparticles.