Optical manipulation of lanthanide-doped nanoparticles: how to overcome their limitations

Since Ashkin's pioneering work, optical tweezers have become an essential tool to immobilize and manipulate microscale and nanoscale objects. The use of optical tweezers is key for a variety of applications, including single-molecule spectroscopy, colloidal dynamics, tailored particle assembly, protein isolation, high-resolution surface studies, controlled investigation of biological processes, and surface-enhanced spectroscopy. In recent years, optical trapping of individual sub-100-nm objects has got the attention of the scientific community. In particular, the three-dimensional manipulation of single lanthanide-doped luminescent nanoparticles is of great interest due to the sensitivity of their luminescent properties to environmental conditions. Nevertheless, it is really challenging to trap and manipulate single lanthanide-doped nanoparticles due to the weak optical forces achieved with conventional optical trapping strategies. This limitation is caused, firstly, by the diffraction limit in the focusing of the trapping light and, secondly, by the Brownian motion of the trapped object. In this work, we summarize recent experimental approaches to increase the optical forces in the manipulation of lanthanide-doped nanoparticles, focusing our attention on their surface modification and providing a critical review of the state of the art and future prospectsThis work was supported by the Ministerio de Ciencia e Innovación de España (PID2019-105195RA-I00) and by Universidad Autónoma de Madrid,Comunidad Autónoma de Madrid(SI1/PJI/2019-00052)

Core-shell rare-earth-doped nanostructures in biomedicine

The current status of the use of core-shell rare-earth-doped nanoparticles in biomedical applications is reviewed in detail. The different core-shell rare-earth-doped nanoparticles developed so far are described and the most relevant examples of their application in imaging, sensing, and therapy are summarized. In addition, the advantages and disadvantages they present are discussed. Finally, a critical opinion of their potential application in real life biomedicine is givenThis work has been partially supported by the Ministerio de Economía y Competitividad de España (MINECO) (MAT2016-75362-C3-1-R), by the Instituto de Salud Carlos III (PI16/ 00812), by the Comunidad Autónoma de Madrid (B2017/ BMD-3867RENIM-CM), by the European Comission (NanoTBTech), and co-financed by European Structural and Investment Fund. This work has also been partially supported by COST action CM1403. L. L. P. thanks the Universidad Autónoma de Madrid for the “Formación de personal investi-gador (FPI-UAM)” program. P. R. S. thanks MINECO and the Fondo Social Europeo (FSE) for the “Promoción del talento y su Empleabilidad en I+D+i” statal program (BES-2014-069410). D. H. O. is grateful to the Instituto de Salud Carlos III for a Sara Borrell Fellowship (CD17/00210

Luminescent sensors for the study of anomalies in the order of water molecules

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de Materiales. Fecha de lectura: 24-05-2019Esta tesis tiene embargado el acceso al texto completo hasta el 24-11-2020Las extrañas características del agua hacen posible la existencia de vida en la Tierra. Sin embargo, a pesar de que es el líquido más estudiado, aún no se conocen las causas de las singularidades que presentan muchas de sus propiedades. Estas peculiaridades se deben principalmente a cómo se ordenan las moléculas de agua, que están unidas entre sí mediante enlaces de puente de hidrógeno. La variación de las características de estos enlaces ocasiona la alteración del orden de las moléculas de agua con la temperatura. En consecuencia, se producen dependencias anómalas de las propiedades del agua con la temperatura. En esta tesis se han investigado las causas, efectos y factores influyentes de la anomalía en la densidad y la anomalía dipolar del agua. Estas anomalías se han estudiado a través de su efecto sobre la variación con la temperatura de la luminiscencia de los iones Eu3+, que son excelentes sensores de cambios estructurales a nivel molecular. Además, como el agua es el solvente empleado para el desarrollo de las aplicaciones de los nanomateriales en biomedicina, se ha determinado cómo pueden afectarles las anomalías. En concreto, se ha investigado el efecto de la anomalía dipolar del agua sobre el intercambio de iones entre nanopartículas luminiscentes de fluoruro. Los resultados obtenidos en esta tesis han permitido comprender mejor cómo varía el orden de las moléculas de agua con la temperatura y el pH y cómo las anomalías afectan a los nanomateriales dispersados en agua.Water’s odd characteristics make the existence of life on earth possible. However, although water is the most studied liquid, the causes of the singularities of most of its properties are not known yet. Its peculiarities are mainly due to the unusual organization of water molecules, which are connected by hydrogen bonds. The variation of hydrogen bonds characteristics with temperature causes the alteration of the order of water molecules. Consequently, water’s properties show anomalous temperature dependencies. In this thesis the causes, effects, and influential factors of the density and dipolar anomalies of water have been investigated. These anomalies have been studied through their effect on the temperature dependence of the luminescence of Eu3+ ions, as these ions are excellent sensors of structure changes at the molecular scale. Moreover, as water is the solvent used for the development of nanomaterials applications in biomedicine, attention has been paid to the effect of water anomalies on them. In particular, the effect of the dipolar anomaly of water on the ion exchange process among fluoride luminescent nanoparticles has been investigated. The results obtained in this thesis have allowed to understand better how the order of water molecules is altered by temperature and pH and how these anomalies affect luminescent nanomaterials dispersed in water

Core–Shell Engineering to Enhance the Spectral Stability of Heterogeneous Luminescent Nanofluids

This work was supported by the Spanish Ministerio de Educación y Ciencia (MAT2016-75362-C3-1-R) and by COST Action CM1403. L.L.-P. thanks the Universidad Autónoma de Madrid for the ‘‘Formación de Personal Investigador (FPI-UAM)’’program. P.H.-G. thanks the Spanish Ministerio de Economia y Competitividad for the Juan de la Cierva program (IJCI-2015-24551). M.P. and A.S. thank University of Verona (Italy) for financial support in the framework of the ‘‘Cooperint 2016’’ and “Ricerca di Base 2015” projects. The work of K.S. was supported by Latvian National Research Program IMIS2 (Grant No. 302/2012).The tendency to the miniaturization of devices and the peculiar properties of the nanoparticles have raised the interest of the scientific community in nanoscience. In particular, those systems consisting of nanoparticles dispersed in fluids, known as nanofluids, have made it possible to overcome many technological and scientific challenges, as they show extraordinary properties. In this work, the loss of the spectral stability in heterogeneous luminescent nanofluids is studied revealing the critical role played by the exchange of ions between different nanoparticles. Such ion exchange is favored by changes in the molecular properties of the solvent, making heterogeneous luminescent nanofluids highly unstable against temperature changes. This work demonstrates how both temporal and thermal stabilities of heterogeneous luminescent nanofluids can be substantially improved by core–shell engineering. This simultaneously avoids the leakage of luminescent ions and the effects of the solvent molecular changes.Ministerio de Ciencia Tecnología y Telecomunicaciones MAT2016-75362-C3-1-R, 302/2012; University of Verona (Italy); European Cooperation in Science and Technology CM1403; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

pH dependence of water anomaly temperature investigated by Eu(III) cryptate luminescence

International audienceAlthough water has been extensively studied, not all of its unique properties have been fully understood. There is still controversy about the temperature at which hydrogen bonds are broken or weakened, producing the anomalous temperature dependence of many water properties. Different temperatures between 23 and 48 °C have been reported, but no study has scrutinized the reasons for this discrepancy. We suggest the determining role of pH in the alteration of the water anomaly temperature. We employed a luminescent europium trisbipyridine cryptate, which is highly sensitive to changes in the arrangement of water molecules and whose luminescence intensity and lifetime are not significantly influenced by variations over a broad pH range. Our results revealed an increase of the crossover temperature from circa 35 °C at pH 3.5 to circa 45 °C at pH 7 to 9, which explains the discrepancies of previous studies. The pH dependence of water anomaly temperature is an important property for a better understanding of water and water-based systems and applications

Determining the 3D orientation of optically trapped upconverting nanorods by in situ single-particle polarized spectroscopy

An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er3+,Yb3+ upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as the relative orientation between optical traps. All these results show the possibility of real time three-dimensional manipulation and tracking of anisotropic nanoparticles with wide potential application in modern nanobiophotonicsThis work was supported by the Spanish Ministerio de Educación y Ciencia (MAT2013-47395-C4-1-R) and by Banco Santander for “proyectos de cooperación interuniversitaria” (2015/ ASIA/06). Patricia Haro-González thanks the Spanish Ministerio de Economía y Competitividad (MINECO) for the Juan de la Cierva program. Paloma Rodríguez-Sevilla thanks the Spanish Ministerio de Economía y Competitividad (MINECO) for the “Promoción del talento y su Empleabilidad en I+D+i” statal program. Dominika Wawrzyńczyk, Marcin Nyk and Marek Samoć acknowledge the support from the National Science Centre under grant DEC-2012/04/M/ST5/00340, by a statutory activity subsidy from the Polish Ministry of Science and Higher Education for the Faculty of Chemistry of Wroclaw University of Technology, as well as from the Foundation for Polish Science under START 2014 programme. This work has received funding from The Royal Society (IE130466). Mark D. Mackenzie acknowledges funding from EPSRC (grant no EP/J500227/

Innovación sobre la docencia y evaluación del laboratorio de Química Física I

Depto. de Química FísicaFac. de Ciencias QuímicasFALSEsubmitte