Real-time nanodiamond thermometry probing in vivo thermogenic responses

Abstract

Real-time temperature monitoring inside living organisms provides a direct measure of their biological activities. However, it is challenging to reduce the size of biocompatible thermometers down to submicrometers, despite their potential applications for the thermal imaging of subtissue structures with single-cell resolution. Here, using quantum nanothermometers based on optically accessible electron spins in nanodiamonds, we demonstrate in vivo real-time temperature monitoring inside Caenorhabditis elegans worms. We developed a microscope system that integrates a quick-docking sample chamber, particle tracking, and an error correction filter for temperature monitoring of mobile nanodiamonds inside live adult worms with a precision of ±0.22°C. With this system, we determined temperature increases based on the worms’ thermogenic responses during the chemical stimuli of mitochondrial uncouplers. Our technique demonstrates the submicrometer localization of temperature information in living animals and direct identification of their pharmacological thermogenesis, which may allow for quantification of their biological activities based on temperature.

Is a Quantum Biosensing Revolution Approaching? Perspectives in NV‐Assisted Current and Thermal Biosensing in Living Cells

“…'s experiment. [ 49 ] A first test allowed to measure the temperature dynamics inside live C. elegans adults worms during environmental temperature changes. The sensitivity reached was 1.4 °C Hz.…”

“…[ 42 ] These exceptional properties, together with their photostability at room‐temperature and the nontoxicity of diamond, [ 43 ] promotes the NV complex as a very promising candidate for biological application. [ 44–49 ] This review will focus on ODMR techniques to detect electromagnetic fields/current as well as thermal gradients, but we want to underline that there are also other advanced techniques for bio‐applications using NV centers, such as T 1 relaxometry, [ 50–52 ] nuclear magnetic resonance (NMR) [ 53,54 ] and magnetic resonance imaging (MRI) spectroscopy, [ 20,55,56 ] that are beyond the scope of this review.…”

Wide-field fluorescent nanodiamond spin measurements toward real-time large-area intracellular thermometry

“…This is because the ODMR data obtained for pixel-saturated NDs may be used for thermometry, as Fig. 1 e does not show a significant effect of pixel saturation on the total detected photon counts, which may be useful, particularly under the positional drift of the NDs because the drift of NDs frequently occurs in biological samples owing to the dynamic change in structures and locomotion 25 , 44 . Figure 3 a,b show images of a single ND at GHz and GHz of the frequency sweep in the ODMR measurement for different sizes of ROIs and the corresponding ODMR spectra, respectively.…”

“…Biological applications of this method have been demonstrated for various cultured cells, including fibroblasts 31 , neurons 23 , and stem cells 43 . It has been recently applied to in vivo nematode worms for studying physiological thermogenesis 44 and the temperature dependence of embryogenesis 45 . These demonstrations have proven the usefulness of ND spin-based thermometry.…”

“…Confocal detection is a point-by-point ND probing technique that is widely used for NV-spin manipulation and detection combined with rapid timing control of photon detection and microwave pulsing 27 , 28 . An example for biological thermometry is the multi-point ODMR method 31 , 34 , 36 that was used for real-time biological thermometry studies 44 , 45 . Camera-based wide-field detection offers parallel probing of multiple NDs simultaneously that enables spin-based ND thermometry at multiple points in a large field of view 23 , 46 , 47 .…”