posted on 2022-01-10, 13:03authored byDiego Herrera-Ochoa, Pedro J. Pacheco-Liñán, Iván Bravo, Andrés Garzón-Ruiz
The
use of two nanoparticles for quantitative pH measurements in
live cells by means of fluorescence lifetime imaging microscopy (FLIM)
is investigated here. These nanoparticles are based on CdSe/ZnS quantum
dots (QDs), functionalized with N-acetylcysteine
(CdSe/ZnS-A) and with a small peptide containing
D-penicillamine and histidine (CdSe/ZnS-PH). CdSe/ZnS-A has tendency to aggregate and nonlinear pH sensitivity
in a complex medium containing salts and macromolecules. On the contrary,
CdSe/ZnS-PH shows chemical stability, low toxicity,
efficient uptake in C3H10T1/2 cells, and good performance as an FLIM
probe. CdSe/ZnS-PH also has key advantages over a
recently reported probe based on a CdSe/ZnS QD functionalized with
D-penicillamine (longer lifetimes and higher pH-sensitivity). A pH(±2σ)
of 6.97 ± 0.14 was determined for C3H10T1/2 cells by FLIM employing
this nanoprobe. In addition, the fluorescence lifetime signal remains
nearly constant for C3H10T1/2 cells treated with CdSe/ZnS-PH for 24 h. These results show the promising applications
of this nanoprobe to monitor the intracellular pH and cell state employing
the FLIM technique.