posted on 2013-09-17, 00:00authored byYing Wang, Ai-Jun Miao, Jun Luo, Zhong-Bo Wei, Jun-Jie Zhu, Liu-Yan Yang
The bioaccumulation
kinetics of thioglycolic acid stabilized CdTe
quantum dots (TGA-CdTe-QDs) in a freshwater alga Ochromonas
danica was comprehensively investigated. Their photoluminescence
(PL) was determined by flow cytometry. Its cellular intensity increased
hyperbolically with exposure time suggesting real internalization
of TGA-CdTe-QDs. This hypothesis was evidenced by the nanoparticle
uptake experiment with heat-killed or cold-treated cells and by their
localization in the vacuoles. TGA-CdTe-QD accumulation could further
be well simulated by a biokinetic model used previously for conventional
pollutants. Moreover, macropinocytosis was the main route for their
internalization. As limited by their diffusion from the bulk medium
to the cell surface, TGA-CdTe-QD uptake rate increased proportionally
with their ambient concentration. Quick elimination in the PL of cellular
TGA-CdTe-QDs was also observed. Such diminishment resulted mainly
from their surface modification by vacuolar biomolecules, considering
that these nanoparticles remained mostly undissolved and their expulsion
out of the cells was slow. Despite the significant uptake of TGA-CdTe-QDs,
they had no direct acute effects on O. danica. Overall,
the above research shed new light on nanoparticle bioaccumulation
study and would further improve our understanding about their environmental
behavior, effects and fate.