Fluorescent nanodiamonds as a robust temperature sensor inside a single cell

Abstract

Thermometers play an important role to study the biological significance of temperature. Fluorescent nanodiamonds (FNDs) with negatively-charged nitrogen-vacancy centers, a novel type of fluorescence-based temperature sensor, have physicochemical inertness, low cytotoxicity, extremely stable fluorescence, and unique magneto-optical properties that allow us to measure the temperature at the nanoscale level inside single cells. Here, we demonstrate that the thermosensing ability of FNDs is hardly influenced by environmental factors, such as pH, ion concentration, viscosity, molecular interaction, and organic solvent. This robustness renders FNDs reliable thermometers even under complex biological cellular environment. Moreover, the simple protocol developed here for measuring the absolute temperature inside a single cell using a single FND enables successful temperature measurement in a cell with an accuracy better than ±1°C.

In situ measurement of intracellular thermal conductivity using heater-thermometer hybrid diamond nanosensor

“…The temperature was measured using FNDs and a home-built microscope, which was reported previously 33 were performed. Through this process, ODMR spectra were obtained from isolated PDA-FND particles located in the field of view.…”

“…In addition, their unique magneto-optical properties allow nanoscale temperature measurement through optically detected magnetic resonance (ODMR) technique with accuracy better than 1 K 30,31 . Since NVCs are deeply embedded inside a diamond crystal with high thermal conductivity (larger than 50 Wm -1 K -1 ) 32 , its thermosensing ability is little influenced by environmental factors 33 . Physically bound FND and GNR serve as a nanoheater and nanothermometer at the same time 26,27 because GNRs release heat when exposed to light via strong surface plasmon resonance 34,35 .…”

Ultrasensitive All-Optical Thermometry Using Nanodiamonds with a High Concentration of Silicon-Vacancy Centers and Multiparametric Data Analysis

“…During past decades, a very active field of non-invasive optical nanothermometry has emerged 14,15 where nanodiamonds imbedded with colour centres have attracted much interest 3,16,17 due to their remarkable optical properties 18 , biocompatibility 19 , and uncomplicated surface functionalization 20 . Although a large number of colour centres exists in diamond, nitrogen vacancy (NV) combined with optically detected magnetic resonance (ODMR) technique have dominated research [21][22][23] .…”

Optical Nanoscale Thermometry: From Fundamental Mechanisms to Emerging Practical Applications

“…Measuring intracellular temperature is a topic of intensive investigation in biophysics for it can help elucidate the dynamics of target metabolic processes inside living cells. The types of nanothermometers employed in this context include organic dyes, [194] fluorescent proteins, [195,196] polymers, [197] and inorganic nanoparticles [198][199][200][201][202][203][204] (cf. Sections 3.1-3.4).…”