Human Blood Biocompatibility of Silver Nanoparticles

Silver nanoparticles are increasingly being used in medical devices for their antimicrobial properties. Present toxicological techniques may not be sufficient to fully determine their safety for use in medical devices. In this talk, in vitro assessment of the hemolytic properties of silver particles in human blood will be discussed. In addition to the observed hemolysis, the possible mechanisms of red blood cell damage were explored in regard to the physical and chemical properties of silver particles.  Four silver particle (two nano-sized, two micro-sized) preparations were dispersed in water and characterized using multiple analytical methods. Particle size and agglomeration were dependent on the suspension media.  Under similar conditions to the hemolysis assay, i.e., with particles added to phosphate buffered saline and plasma, the size of the nanoparticles increased compared to particles suspended in water. Nano-sized particles exhibited higher hemolysis than micro-sized particles at mass concentrations greater than 220 ug/ml. While significant particle size changes occurred due to interaction with media components, the higher level of hemolysis observed with nanoparticles compared to micro-sized particles may be related to greater surface area, increased silver ion release, and direct nanoparticle interactions with red blood cells. These in vitro hemolysis results suggest that blood-contacting medical devices containing silver nanoparticles should be carefully evaluated for their hemolytic potential.