Tsai, Evaline S. and Joud, Fadwa and Wiesholler, Lisa M. and Hirsch, Thomas and Hall, Elizabeth A. H. (2020) Upconversion nanoparticles as intracellular pH messengers. ANALYTICAL AND BIOANALYTICAL CHEMISTRY, 412 (24). pp. 6567-6581. ISSN 1618-2642, 1618-2650
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Upconversion nanoparticles (UCNPs) should be particularly well suited for measurement inside cells because they can be imaged down to submicrometer dimensions in near real time using fluorescence microscopy, and they overcome problems, such as photobleaching, autofluorescence, and deep tissue penetration, that are commonly encountered in cellular imaging applications. In this study, the performance of an UCNP modified with a pH-sensitive dye (pHAb) is studied. The dye (emission wavelength 580 nm) was attached in a polyethylene imine (PEI) coating on the UCNP and excited via the 540-nm UCNP emission under 980-nm excitation. The UC resonance energy transfer efficiencies at different pHs ranged from 25 to 30% and a Forster distance of 2.56 nm was predicted from these results. Human neuroblastoma SH-SY5Y cells, equilibrated with nigericin H+/K+ ionophore to equalize the intra- and extracellular pH, showed uptake of the UCNP-pHAb conjugate particles and, taking the ratio of the intensity collected from the pHAb emission channel (565-630 nm) to that from the UCNP red emission channel (640-680 nm), produced a sigmoidal pH response curve with an apparent pK(a) for the UCNP-pHAb of similar to 5.1. The UCNP-pHAb were shown to colocalize with LysoBrite dye, a lysosome marker. Drug inhibitors such as chlorpromazine (CPZ) and nystatin (NYS) that interfere with clathrin-mediated endocytosis and caveolae-mediated endocytosis, respectively, were investigated to elucidate the mechanism of nanoparticle uptake into the cell. This preliminary study suggests that pH indicator-modified UCNPs such as UCNP-pHAb can report pH in SH-SY5Y cells and that the incorporation of the nanoparticles into the cell occurs via clathrin-mediated endocytosis.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | QUANTUM-DOT; ENERGY-TRANSFER; PROBE; DESIGN; CELLS; INTERNALIZATION; COLOCALIZATION; NANOSENSORS; ENDOCYTOSIS; NANOPROBES; Upconversion nanoparticles; Nanosensors; pH measurements; Intracellular; Fluorescence microscopy; Endocytosis |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Analytische Chemie, Chemo- und Biosensorik |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 18 Mar 2021 11:30 |
| Last Modified: | 18 Mar 2021 11:30 |
| URI: | https://pred.uni-regensburg.de/id/eprint/44248 |
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