Ratiometric Nanothermometer Based on a Radical Excimer for In Vivo Sensing

Abstract

Ratiometric fluorescent nanothermometers with near‐infrared emission play an important role in in vivo sensing since they can be used as intracellular thermal sensing probes with high spatial resolution and high sensitivity, to investigate cellular functions of interest in diagnosis and therapy, where current approaches are not effective. Herein, the temperature‐dependent fluorescence of organic nanoparticles is designed, synthesized, and studied based on the dual emission, generated by monomer and excimer species, of the tris(2,4,6‐trichlorophenyl)methyl radical (TTM) doping organic nanoparticles (TTMd‐ONPs), made of optically neutral tris(2,4,6‐trichlorophenyl)methane (TTM‐αH), acting as a matrix. The excimer emission intensity of TTMd‐ONPs decreases with increasing temperatures whereas the monomer emission is almost independent and can be used as an internal reference. TTMd‐ONPs show a great temperature sensitivity (3.4% K−1 at 328 K) and a wide temperature response at ambient conditions with excellent reversibility and high colloidal stability. In addition, TTMd‐ONPs are not cytotoxic and their ratiometric outputs are unaffected by changes in the environment. Individual TTMd‐ONPs are able to sense temperature changes at the nano‐microscale. In vivo thermometry experiments in Caenorhabditis elegans (C. elegans) worms show that TTMd‐ONPs can locally monitor internal body temperature changes with spatio‐temporal resolution and high sensitivity, offering multiple applications in the biological nanothermometry field.

Nonequilibrium Colloids: Temperature-Induced Bouquet Formation of Flower-like Micelles as a Time-Domain-Shifting Macromolecular Heat Alert

“…These effects might represent a quick, adaptable, and cheap method to monitor temperature for storage and transport purposes (the ingredients water, poloxamer, ferricyanide, and DMAEMA are rather inexpensive). Our method fits into the line of recent reports on sensors for temperature or food freshness. , …”

Exploring the Luminescence, Redox, and Magnetic Properties in a Multivariate Metal–Organic Radical Framework

“…Persistent organic radicals are open-shell molecules with fascinating electronic, optical, and magnetic properties that have been explored as functional molecular materials toward a wide range of applications, , including electronics, spintronics, energy storage, or biomedicine . Although most organic radicals are nonemissive, luminescent triphenylmethyl (trityl) radical derivatives with doublet electronic configuration have received a great deal of interest for applications in organic light-emitting diodes, circularly polarized luminescence, sensing, nanothermometry, etc. − However, trityl radicals do not usually exhibit luminescence in the solid state due to quenching caused by exciton migration between nearby emissive radical centers. , A recent strategy to solve this problem has been to prepare solid solutions with the corresponding nonradical derivatives to isolate the radical centers …”

A Highly Luminescent Metallo-Supramolecular Radical Cage

“…Recently, luminescent radical materials have garnered a great deal of attention and interest from academia − and have been widely applied in organic light emitting diodes (OLEDs), ,, triplet sensitization, magnetoluminescence, − fluorescent sensors, − circularly polarized luminescence, , photodynamic therapy, and so on. Most luminescent radical materials with high efficiency are organic radical molecules, including mono-, di-, tri-, and tetraradicals. ,, However, it is worth noting that the luminescence of metal-radicals tends to be quenched after formation of metallo-complexes. − Thus, the development of luminescent metal-radical materials has been constrained in the past years.…”