title: Carbon Dot Nanothermometry: Intracellular Photoluminescence Lifetime Thermal Sensing.
abstract: Nanoscale biocompatible photoluminescence (PL) thermometers that can be used to accurately and reliably monitor intracellular temperatures have many potential applications in biology and medicine. Ideally, such nanothermometers should be functional at physiological pH across a wide range of ionic strengths, probe concentrations, and local environments. Here, we show that water-soluble N,S-co-doped carbon dots (CDs) exhibit temperature-dependent photoluminescence lifetimes and can serve as highly sensitive and reliable intracellular nanothermometers. PL intensity measurements indicate that these CDs have many advantages over alternative semiconductor- and CD-based nanoscale temperature sensors. Importantly, their PL lifetimes remain constant over wide ranges of pH values (5-12), CD concentrations (1.5 × 10-5to 0.5 mg/mL), and environmental ionic strengths (up to 0.7 mol·L-1NaCl). Moreover, they are biocompatible and nontoxic, as demonstrated by cell viability and flow cytometry analyses using NIH/3T3 and HeLa cell lines. N,S-CD thermal sensors also exhibit good water dispersibility, superior photo- and thermostability, extraordinary environment and concentration independence, high storage stability, and reusability-their PL decay curves at temperatures between 15 and 45 °C remained unchanged over seven sequential experiments. In vitro PL lifetime-based temperature sensing performed with human cervical cancer HeLa cells demonstrated the great potential of these nanosensors in biomedicine. Overall, N,S-doped CDs exhibit excitation-independent emission with strongly temperature-dependent monoexponential decay, making them suitable for both in vitro and in vivo luminescence lifetime thermometry.
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Sergii
authors.identifier: 0000-0002-6371-8795
authors.initials: S
authors.lastname: Kalytchuk
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Poláková
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Jens P
authors.initials: JP
authors.lastname: Froning
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Klara
authors.initials: K
authors.lastname: Cepe
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , Šlechtitelů 27, 783 71 Olomouc, Czech Republic.|Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong SAR.
authors.forename: Andrey L
authors.identifier: 0000-0002-8263-8141
authors.initials: AL
authors.lastname: Rogach
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Radek
authors.identifier: 0000-0002-3147-2196
authors.initials: R
authors.lastname: Zbořil
mesh_terms: D000818:Animals; D002244:Carbon / Q000737:chemistry / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D006367:HeLa Cells; D006801:Humans; D049449:Luminescence; D051379:Mice; D041681:NIH 3T3 Cells; D036103:Nanotechnology; D055668:Photochemical Processes; D045663:Quantum Dots / Q000737:chemistry*; D013696:Temperature
chemical_list: D002244:Carbon
keywords: HeLa cancer cells; carbon dots; colloidal nanomaterials; intracellular temperature; luminescence lifetime thermal sensing; nanothermometer; photoluminescence