Real-Time Intracellular Temperature Imaging Using Lanthanide-Bearing Polymeric Micelles

Abstract

Measurement of thermogenesis in individual cells is a remarkable challenge due to the complexity of the biochemical environment (such as pH and ionic strength) and to the rapid and yet not well-understood heat transfer mechanisms throughout the cell. Here, we present a unique system for intracellular temperature mapping in a fluorescence microscope (uncertainty of 0.2 K) using rationally designed luminescent Ln 3+ -bearing polymeric micellar probes (Ln=Sm, Eu) incubated in breast cancer MDA-MB468 cells.2D thermal images recorded increasing the temperature of the cells culture medium between 296 and 304 K shows inhomogeneous intracellular temperature progressions up to ~20 degrees and subcellular gradients of ~5 degrees between the nucleolus and the rest of the cell, illustrating the thermogenic activity of the different organelles and highlighting the potential of this tool to study intracellular processes.

A Theoretical Framework for Ratiometric Single Ion Luminescent Thermometers—Thermodynamic and Kinetic Guidelines for Optimized Performance

“…[80] Optical (nano)thermometry has shown high potential in the experimental elucidation of several thermodynamic phenomena at the nanoscale and its superiority over, e.g., thermographic methods, which can only measure surface temperatures. Demonstrative examples include the experimental measurement of the Brownian velocity of nanocrystals in suspensions, [81] the in vivo detection of the brain [55] or intracellular [28,82] temperature, direct measurements of (transient) heat transfer properties of a lipid bilayer, [83] temperature monitoring of liquid or gas flows [23,84] or also detection of local temperature increases on catalysts [85,86] due to exothermic reactions. In all cases, luminescence thermometry particularly captivates by the simplicity of the respective experimental setup consisting of a laser source, the luminescent nanocrystals in contact with the medium to be characterized and a fast processing detection system.…”

Rational Design of Ratiometric Luminescence Thermometry Based on Thermally Coupled Levels for Bioapplications

“…Great efforts have been devoted to designing and exploring novel optical materials as potential luminescence thermometers, including quantum dots (QDs), lanthanide (Ln 3+ ) doped polymeric, organic dyes, inorganic, and hybrid materials. [ 13–18 ] Among these materials, Ln 3+ ‐doped inorganic phosphors have been widely investigated as luminescence thermometers thanks to their low toxicity, superior physicochemical stability, narrow bandwidth, and excellent luminescence properties. Especially, near‐infrared (NIR) light‐driven phosphors at nanoscale, such as upconversion nanoparticles (UCNPs) that capable of converting NIR stimulation into visible emission, present the advantages of deep‐tissue penetration, minimized background autoluminescence and photodamage, which have great potential applications in diagnostics, optical bio‐imaging, therapeutics and drug delivery, especially in subcutaneous and intracellular thermometry.…”

Particle size-related limitations of persistent phosphors based on the doped Y3Al2Ga3O12 system

“…Persistent luminescence (PersL) nanophosphors activated by doping with lanthanide and transition metal ions have recently gained much attention due to their promising applications in the fields of bioimaging 1 , 2 , optical nano-thermometry 3 , solar-blind glowing tags in bright daylight 4 , safety displays 5 , 6 , etc. Many research groups around the world are strongly motivated to develop new hosts for such phosphors and new synthetic routes 5 – 9 .…”