In anticipation of the increased use of various forms of silver as an antimicrobial agent in medical devices, the objective of this study was to evaluate the in vitro hemolytic potential of silver nanoparticles in dilute human blood, and to relate particle properties to possible mechanisms of red blood cell damage. To relate hemolysis to physical and chemical properties, four different silver particle preparations were characterized using transmission electron microscopy, dynamic light scattering, Raman and energy dispersive X-ray spectroscopies, and zeta potential measurement. Silver ions released from the particles were measured using an ion-selective electrode and inductively coupled plasma mass spectroscopy. Aqueous silver particle suspensions with varying mass concentrations were mixed with heparinized human blood diluted in phosphate buffered saline. Silver nanoparticles (diameter <100 nm) were significantly more hemolytic compared to micron-sized silver particles with similar surface chemical composition at equivalent mass concentrations. Hemolysis was dependent on particle concentration, and substantive levels (>10 %) occurred at nanoparticle concentrations at and above 220 µg/ml. Hemolysis results were also dependent on the choice of dispersing media; silver nanoparticles mixed directly in buffered saline aggregated rapidly (and formed insoluble AgCl) and did not produce hemolysis. In contrast, particles dispersed in water before being exposed to saline or blood/plasma remained in solution longer and were able to induce hemolysis. The increased total surface area of nano-sized silver particles may contribute to increased levels of in vitro hemolysis through currently uncharacterized interactions of silver ions and nanoparticles with red blood cells.
Citation: Toxicological Sciences
Pub Type: Journals
Nanoparticles , concentration, colloidal solution, extinction coefficient, dry mass, quartz crystal microbalance