Enhanced electric field sensitivity of quantum dot/rod two-photon fluorescence and its relevance for cell transmembrane voltage imaging

Stijn Jooken,Koen Clays,Tangi Aubert,Zeger Hens,Geert Callewaert,Carmen Bartic,Yovan De Coene,Thierry Verbiest,Dániel Zámbó,Olivier Deschaume,Dirk Dorfs

doi:10.1515/nanoph-2021-0077

Stijn Jooken, Koen Clays + Show 9 more

Open Access

https://doi.org/10.1515/nanoph-2021-0077

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Abstract

Abstract The optoelectronic properties of semiconductor nanoparticles make them valuable candidates for the long-term monitoring of transmembrane electric fields in excitable cells. In this work, we show that the electric field sensitivity of the fluorescence intensity of type-I and quasi-type-II quantum dots and quantum rods is enhanced under two-photon excitation compared to single-photon excitation. Based on the superior electric field sensitivity of the two-photon excited fluorescence, we demonstrate the ability of quantum dots and rods to track fast switching E-fields. These findings indicate the potential of semiconductor nanoparticles as cellular voltage probes in multiphoton imaging.

Highlights

Quantum dots (QDs) or quantum rods (QRs) are semiconductor nanoparticles (NP) typically composed of II–VI, III–V or IV–VI materials such as CdSe, CdS, InP or PbS among others
We show that the electric field sensitivity of the fluorescence intensity of type-I and quasitype-II quantum dots and quantum rods is enhanced under two-photon excitation compared to single-photon excitation
We show for the first time that under 2P excitation, the electric field sensitivity is enhanced with respect to 1P excitation for three different water-solubilized NPs, a type-I CdSe/ZnS QD with a 3.9 nm core size and a 6.3 nm total diameter, a quasi-type-II CdSe/CdS QD with a 3.7 nm core size and 8.9 nm total diameter and a quasi-type-II CdSe/CdS dot-inrod with a 3.7 nm core size, 35 nm length and 5 nm width

Summary

Introduction

Quantum dots (QDs) or quantum rods (QRs) are semiconductor nanoparticles (NP) typically composed of II–VI, III–V or IV–VI materials such as CdSe, CdS, InP or PbS among others. Their sizes are smaller than the Bohr exciton radius giving them unique optical and optoelectronic properties due to the confinement of the charge carriers in all three dimensions. Quantum dots have a broad absorbance and a narrow emission spectrum (ideal for fluorescence multiplexing) that can be tuned by varying the size of the particle Their quantum yields (QY) and longterm photostability are much less affected by photobleaching than those of organic fluorophores. The latter is referred to as a quasi-type-II NP

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