In most cases, we saw an increase in mean nanoparticle size following (unmodified, aminemodified) polystyrene latex particle incubation with protein-containing media and a further increase in nanoparticle size during exposure to protein-containing medium for up to 24 hours (Figure ). This trend correlates with previous findings where gold nanoparticles showed an increase in particle size following prolonged incubation within protein containing media .