Adhesion and internalization of functionalized polystyrene latex nanoparticles toward the yeast Saccharomyces cerevisiae

AbstractThe toxicity and the internalization, adhesion, and dispersion behavior of manufactured polystyrene latex (PSL) nanoparticles (nominal diameter: 50nm) with various functional groups toward the yeast Saccharomyces cerevisiae (which was applied as a model eukaryote) were examined using the colony count method, and microscopic observations. The colony count tests suggested that PSL nanoparticles with a negative surface charge showed little or no toxicity toward the yeast. In contrast, PSL nanoparticles with an amine functional group and a positive surface charge (p-Amine) displayed a high toxicity in 5mM NaCl. However, the yeast cells were mostly unharmed by the p-Amine in 154mM NaCl, results that were quite different from the toxicological effects observed when Escherichia coli was used as a model prokaryote. Confocal and atomic force microscopies indicated that in 5mM NaCl, the p-Amine nanoparticles entirely covered the surface of the yeast, and cell death occurred; in contrast, in 154mM NaCl, the p-Amine nanoparticles were internalized via endocytosis, and cell death did not occur