Luminescent Yb3+,Er3+-Doped α-La(IO3)3 Nanocrystals for Neuronal Network Bio-Imaging and Nanothermometry.

Géraldine Dantelle,Cécile Delacour,Valérie Reita

doi:10.3390/nano11020479

Abstract

Dual-light emitting Yb3+,Er3+-codoped α-La(IO3)3 nanocrystals, known to exhibit both second harmonic signal and photoluminescence (PL), are evaluated as optical nanoprobes and thermal sensors using both conventional microscopes and a more sophisticated micro-PL setup. When loaded in cortical and hippocampal neurons for a few hours at a concentration of 0.01 mg/mL, a visible PL signal arising from the nanocrystals can be clearly detected using an epifluorescent conventional microscope, enabling to localize the nanocrystals along the stained neurons and to record PL variation with temperature of 0.5% K−1. No signal of cytotoxicity, associated with the presence of nanocrystals, is observed during the few hours of the experiment. Alternatively, a micro-PL setup can be used to discriminate the different PL lines. From ratiometric PL measurements, a relative thermal sensitivity of 1.2% K−1 was measured.

Highlights

Temperature is a robust parameter that describes and predicts the state of many systems [1]
We demonstrate the possibility to use two different optical microscopy techniques to obtain a local temperature measurement withinmicroscopy cultured neuron networks: In this work, we demonstrate the possibility to use two different optical fluorescent-based imagingmeasurement and micro-PLwithin spectroscopy
FITC-filter, which is a promising strategy for cell thermometry because it can be non-invasive and can makes the technology ready to use in cell culture laboratories

Summary

Introduction

Temperature is a robust parameter that describes and predicts the state of many systems [1] In neuronal networks, it is strongly linked with the metabolism and state of cells, triggering biochemical reactions, activation rates, and thermal sensitive ionic channels. At sub-cellular scales, the expected changes of temperature associated with cellular functions or disfunction is expected to be very weak (100 mW, 10−5 K) and/or localized (100–1 nm) which makes the measure highly challenging [2]. Such small variations could remain hidden and screened by the surrounding extracellular solution which exhibits high thermal conductivity, close to water, around 0.6 Wm K−1 [3]. Luminescent nanoprobes can be internalized by neurons or adsorbed on their membranes and be in close contact with the reactive sites, providing a method to sense local and weak variations of temperature along many individual cells at the same time [6,7]

Methods

Discussion

Conclusion