Bismuth sulphide polyvinylpyrrolidone nanoparticles

Excerpt

X-ray imaging, or computed tomography (CT), visualizes tissue density differences that provide the image contrast produced by X-ray attenuation between soft tissues and electron-dense bone (1). Contrast enhancement with the use of X-ray contrast (radiopaque) agents are needed to increase the degree of contrast between diseased tissues and normal tissues. Water-soluble X-ray contrast agents are generally based on small tri-iodobenzene compounds such as monomers or dimers (2), which can be ionic (high osmolality) or nonionic (low osmolality). When injected intravenously, commonly via intra-arterial catheterization, these agents exhibit highly nonspecific vascular permeation and rapid renal excretion, which limits their targeting performance.

Bismuth salts were used as X-ray contrast agents in the gastrointestinal tract as early as 1897 (1). However, their use did not continue because high doses of bismuth salts are toxic. Rabin et al. (3) have performed experiments using polyvinylpyrrolidone (PVP)-coated Bi₂S₃ nanoparticles (BPNPs) as a CT contrast agent. This preparation exhibited excellent stability, high X-ray absorption (5-fold better than iodine provided as iopromide), a good efficacy/safety profile, long blood half-life, and enhanced CT contrast of the vasculature, liver, and lymph nodes in mice.