Differences in Immunological Impact of Chemically and Biologically Synthesized Silver Nanoparticles

Silver nanoparticles (AgNPs) are widely used for their antimicrobial properties but pose risks like environmental contamination and potential harm to human health. Nanoparticles' small size facilitates translocation within the body, often bringing them into contact with blood. Most toxicological research focuses on chemically synthesized AgNPs (CAgNPs) and their effects on microbes and animal cells. Fewer studies explore biologically synthesized AgNPs (BAgNPs) on animal cells, and their impact on blood components is uncertain with varied findings due to differences in size and stability. This study examined BAgNPs' effects on blood components in healthy and diseased states, using algae Parachlorella kessleri for synthesis. Nanoparticle size and morphology were assessed via TEM and UV-Vis spectrophotometry. Exposure to BAgNPs resulted in an increased number of echinocytes, reduced neutrophils, and decreased leukocyte viability. Unlike CAgNPs, BAgNPs did not increase macrophage proliferation. Differences in biological properties between BAgNPs and CAgNPs stem from their colloidal stability in varying environments. CAgNPs, stabilized electrostatically, exhibited greater aggregation in environments with higher salinity and lower pH, diminishing their biological effects in human blood. Hence, electrostatically stabilized chemically produced AgNPs may not be suitable for biomedical applications.