A new approach to precise mapping of local temperature fields in submicrometer aqueous volumes

Abstract

Nanodiamonds hosting temperature-sensing centers constitute a closed thermodynamic system. Such a system prevents direct contact of the temperature sensors with the environment making it an ideal environmental insensitive nanosized thermometer. A new design of a nanodiamond thermometer, based on a 500-nm luminescent nanodiamond embedded into the inner channel of a glass submicron pipette is reported. All-optical detection of temperature, based on spectral changes of the emission of “silicon-vacancy” centers with temperature, is used. We demonstrate the applicability of the thermometric tool to the study of temperature distribution near a local heater, placed in an aqueous medium. The calculated and experimental values of temperatures are shown to coincide within measurement error at gradients up to 20 °C/μm. Until now, temperature measurements on the submicron scale at such high gradients have not been performed. The new thermometric tool opens up unique opportunities to answer the urgent paradigm-shifting questions of cell physiology thermodynamics.

Heat Release by Isolated Mouse Brain Mitochondria Detected with Diamond Thermometer

“…The design principle of the diamond thermometer device was exhaustively described in [ 1 ]. Its backbone consists of a glass microcapillary with a low-strain single diamond crystal fixed at the tip of the capillary.…”

“…The temperature in the chamber was changed in increments of 10 °C. At each step, the SiV luminescence spectrum was recorded and the spectral position of the zero-phonon line maximum was determined according to the algorithm proposed in our previous work [ 1 ].…”

“…Experimental detection of heat production in a single living cell attributed to its different compartments, organelles, ionic pumps, and ionic channels has long been a cutting edge challenge for modern experimental approaches in cell physiology research. The proven existence of sharp steady-state temperature gradients (tens of degrees °C) in submicrometer watery volumes near a nanoscale heat source [ 1 ] puts forward a beneficial base for the thermal signaling concept [ 2 ], supposing that living cells are capable of creating significant temperature gradients at nanoscale, engaging these ultralocal thermodynamic events as a variable driving force to govern cascades of morphological, biochemical, and electrical intracellular processes. Therefore, experimental uncovering of the signaling role of the nanoscale thermodynamic events bound to biochemical processes and the thermodynamics around ionic channels and pumps has become an ultimate priority.…”

Opto-thermal technologies for microscopic analysis of cellular temperature-sensing systems

“…Luminescent nanosheets containing the temperature-sensitive dye europium (III) thenoyltrifluoroacetonate trihydrate (Eu-TTA) visualize the temperature distribution on the glass surface during optical microheating of solution (Itoh et al 2014;Oyama et al 2020). Romshin et al determined the temperature gradient using a fluorescent nanodiamond (FND) attached to the tip of a glass micropipette (Romshin et al 2021).…”

“…Gold nanorod (AuNR), gold nanoshell (AuNS), carbon nanotube (CNT), and carbon nanohorn (CNH) are excited by near-infrared (NIR) light (see text for details). Right, glass pipette that either encloses luminescent thermometer europium (III) thenoyltrifluoroacetonate trihydrate (Eu-TTA) (Zeeb et al 2004) or attaches a fluorescent nanodiamond (FND) at the tip (Romshin et al 2021) detect local temperature in extracellular solution. Thermometer nanosheet containing Eu-TTA visualizes surface temperature of cells (Itoh et al 2014;Oyama et al 2020).…”