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Universidad Autonoma de Madrid, Comunidad Autónoma de Madrid, Ministerio de Educación y Ciencia (España), Banco Santander-CEAL-UAM, Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ), Fundacao de Amparo a Pesquisa do Estado de Alagoas (FAPEAL), Natural Sciences and Engineering Research Council of Canada (NSERC), Concordia University, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Está depositada la versión postprint del artículo, Quantum dot based-thermometry, in combination with double beam confocal microscopy and infrared thermal imaging, has been used to investigate the heating efficiency of multi-walled carbon nanotubes (MWCNTs) under optical excitation within the first (808 nm) and second (1090 nm) biological windows as well as in the spectral region separating them (980 nm). It has been found that for the three excitation wavelengths the heating efficiency of MWCNTs (10 nm in diameter and 1.5 mu m in length) is close to 50%. Despite this "flat" heating efficiency, we have found that the excitation wavelength is, indeed, critical during in vivo experiments due to the spectral dependence of both tissue absorption and scattering coefficients. It has been concluded that efficiency and selectivity of in vivo photothermal treatments based on MWCNTs are simultaneously optimized when laser irradiation lies within the first or second biological window., Ministerio de Educación y Ciencia (España), Universidad Autonoma de Madrid, Comunidad Autónoma de Madrid, Fundacion Dr Manuel Morales, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Acquiring the temperature of a single living cell is not a trivial task. In this paper, we devise a novel nanothermometer, capable of accurately determining the temperature of solutions as well as biological systems such as HeLa cancer cells. The nanothermometer is based on the temperature-sensitive fluorescence of NaYF4:Er3+,Yb3+ nanoparticles, where the intensity ratio of the green fluorescence bands of the Er3+ dopant ions (H-2(11/2) -> I-4(15/2) and S-4(3/2) -> I-4(15/2)) changes with temperature. The nanothermometers were first used to obtain thermal profiles created when heating a colloidal solution of NaYF4:Er3+,Yb3+ nanoparticles in water using a pump-probe experiment. Following incubation of the nanoparticles with HeLa cervical cancer cells and their subsequent uptake, the fluorescent nanothermometers measured the internal temperature of the living cell from 25 degrees C to its thermally induced death at 45 degrees C., Universidad Autonoma de Madrid, Banco Santander-CEAL-UAM, Natural Sciences and Engineering Research Council of Canada (NSERC), Gouvernement du Quebec, Ministere du Developpement economique, de l'Innovation et de l'Exportation, Comunidad de Madrid, Ministerio de Educación y Ciencia (España), Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Laser-induced thermal effects in optically trapped microspheres and single cells are investigated by quantum dot luminescence thermometry. Thermal spectroscopy has revealed a non-localized temperature distribution around the trap that extends over tens of micrometers, in agreement with previous theoretical models besides identifying water absorption as the most important heating source. The experimental results of thermal loading at a variety of wavelengths reveal that an optimum trapping wavelength exists for biological applications close to 820 nm. This is corroborated by a simultaneous analysis of the spectral dependence of cellular heating and damage in human lymphocytes during optical trapping. This quantum dot luminescence thermometry demonstrates that optical trapping with 820 nm laser radiation produces minimum intracellular heating, well below the cytotoxic level (43 degrees C), thus, avoiding cell damage., Universidad Autonoma de Madrid, Comunidad Autónoma de Madrid, Ministerio de Educación y Ciencia (España), Malta Consolider-Ingenio, Caja Madrid Foundation, Fondazione Cariverona, Fundacion Dr. Manuel Morales, Banco Santander, CEAL-UAM through the UAM-NUS cooperation project, UK Research & Innovation (UKRI), Engineering & Physical Sciences Research Council (EPSRC), Heriot Watt University Life Science Interface Theme Scholarship, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Ag2S nanoparticles (NPs) emerge as a unique system that simultaneously features in vivo near-infrared (NIR) imaging, remote heating, and low toxicity thermal sensing. In this work, their capabilities are extended into the fields of optical coherence tomography (OCT), as contrast agents, and NIR probes in both ex vivo and in vivo experiments in eyeballs. The new dual property for ocular imaging is obtained by the preparation of Ag2S NPs ensembles with a biocompatible amphiphilic block copolymer. Rather than a classical ligand exchange, where surface traps may arise due to incomplete replacement of surface sites, the use of this polymer provides a protective extra layer that preserves the photoluminescence properties of the NPs, and the procedure allows for the controlled preparation of submicrometric scattering centers. The resulting NPs ensembles show extraordinary colloidal stability with time and biocompatibility, enhancing the contrast in OCT with simultaneous NIR imaging in the second biological window. © 2023 The Authors. Small published by Wiley-VCH GmbH.

Upconverting nanoparticles (UCNPs) have been used as optical probes in a great variety of scenarios ranging from cells to animal models. When optically trapped, a single UCNP can be remotely manipulated making possible, for instance, thermal scanning in the surroundings of a living cell. When conventional optics is used, the stability of an optically trapped UCNP is very limited. Its reduced size leads to optical potentials comparable to thermal energy, and up to now, stable optical trapping of a UCNP has been demonstrated only close to room temperature. This fact limits their use above room temperature, for instance, the use to investigate protein denaturalization that occurs in the 40–50 °C range. In this work, stable optical trapping of a single UCNP in the 20–90 °C range has been demonstrated by using a photonic nanojet. The use of an optically trapped microsphere makes it possible to overcome the diffraction limit producing another optical trap of smaller size and enhanced strength. This simple strategy leads not only to an improvement in the thermal stability of the optical trap but also to an enhancement of the emission intensity generated by the optically trapped UCNP. © 2021 Wiley-VCH GmbH, QC 20211116