Thermoresponsive Polymeric Nanolenses Magnify the Thermal Sensitivity of Single Upconverting Nanoparticles

Lanthanide-based upconverting nanoparticles (UCNPs) are trustworthy workhorses in luminescent nanothermometry. The use of UCNPs-based nanothermometers has enabled the determination of the thermal properties of cell membranes and monitoring of in vivo thermal therapies in real time. However, UCNPs boast low thermal sensitivity and brightness, which, along with the difficulty in controlling individual UCNP remotely, make them less than ideal nanothermometers at the single-particle level. In this work, it is shown how these problems can be elegantly solved using a thermoresponsive polymeric coating. Upon decorating the surface of NaYF4:Er3+,Yb3+ UCNPs with poly(N-isopropylacrylamide) (PNIPAM), a >10-fold enhancement in optical forces is observed, allowing stable trapping and manipulation of a single UCNP in the physiological temperature range (20–45 °C). This optical force improvement is accompanied by a significant enhancement of the thermal sensitivity— a maximum value of 8% °C+1 at 32 °C induced by the collapse of PNIPAM. Numerical simulations reveal that the enhancement in thermal sensitivity mainly stems from the high-refractive-index polymeric coating that behaves as a nanolens of high numerical aperture. The results in this work demonstrate how UCNP nanothermometers can be further improved by an adequate surface decoration and open a new avenue toward highly sensitive single-particle nanothermometryThis work was supported by the Ministerio de Ciencia e Innovación de España (PID2019-106211RB-I00 PID2019-105195RA-I00 and MAT2017- 83111R), by the Comunidad de Madrid (S2017/BMD-3867 RENIM-CM), co-financed by European Structural and Investment Fund and by the Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid (SI1/PJI/2019-00052 and PR38/21-36 ANTICIPA-CM). D.L. acknowledges a scholarship from the China Scholarship Council (201808350097). J.R.B. acknowledges the support from Carl Tryggers Foundation (CTS18:229). M.I.M acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación, through the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805-M) and the MELODIA PGC2018-095777-B-C22 proje

Energia solar disponible en la ciudad de México

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: En el año 2014, con recursos del Instituto de Ciencia y Tecnología del Distrito Federal (PINVII-7), se instalaron 10 piranómetros en las estaciones de la Red Automática de Monitoreo Atmosférico (RAMA), de la Secretaría del Medio Ambiente de la Ciudad de México. Estos instrumentos se encuentran conectados al sistema de adquisición de datos de la RAMA por lo que existe una medición cada minuto. Los instrumentos fueron calibrados por el Servicio Solarimétrico Mexicano y referenciados a la Escala Radiométrica Mundial, garantizando que la calibración de las mediciones. Con la información solarimétrica de esta red, durante sus primeros cuatro años, se elaboraron mapas de Irradiación Solar Global en superficie, así como la Base de Datos correspondiente. Toda la información y los mapas, se encuentra disponible en la página de Internet del Servicio Solarimétrico Mexicano y puede ser consultada libremente (http://areas.geofisica.unam.mx/solarimetrico/). Este proyecto no tiene fecha para concluir, por lo que cada año se incrementará la base de datos y los mapas se volverán a elaborar anualmente para aumentar su certidumbre.ABSTRACT: In 2014, with funds of the Institute of Science and Technology of Mexico City (PINVII-7), 10 pyranometers were installed in stations from the Automatic Network of Atmospheric Monitoring (RAMA), of the Secretariat of the Environment of México City. These instruments are connected to the data acquisition system of the RAMA, sampled every minute. The instruments were calibrated by the Mexican Solarimetric Service and referenced to the Global Radiometric Scale, so the information generated is considered reliable. With the first four years information of this network, Global Solar Irradiation maps were prepared on the surface, as well as the corresponding Data Base. All information and maps are available on the website of the Solarimetric Mexican Service http://areas.geofisica.unam.mx/solarimetrico/ and can be consulted freely. This project does not have an ending date, so the database will be increased each year and the maps will be re-prepared annually to increase their certainty.info:eu-repo/semantics/publishedVersio

Metal concentrations in sediments from tourist beaches of Huatulco, Oaxaca, Mexico: an evaluation of post-Easter week vacation

Thirty-eight sediment samples were collected from the inter-tidal beaches of Huatulco located in the Pacific coast of Southern Mexico. They were analyzed for leachable trace metals (LTMs) (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Fe) to evaluate the metal concentration caused by the Easter week tourist activities period and before that. Concentration pattern of LTMs indicates that Fe (avg. 7482 mg kg-1), Mn (avg. 69.24 mg kg-1), Cr (avg. 89.25 mg kg-1) are enriched, which is also supported by the correlation of other metals. Geoaccumulation (Igeo) and enrichment factor (EF) calculations infer that higher values of Fe, Mn, Cr, and As are not anthropogenic and it is possibly the result of mineralogical assemblage. Comparison of LTMs with other geographical regions and eco-toxicological values deduced from sediment quality guidelines (SQGs) emphasize that As, Cr, Cd, Mn, and Ni are in higher concentrations and the bio-available elements should be monitored

Structure and dynamics of a thermoresponsive microgel around Its volume phase transition temperature

Sustained drug delivery requires the use of multifunctional devices with enhanced properties. These properties include responsiveness to external stimuli (such as temperature, pH, ionic strength), ability to deliver suitably designed ligands to specific receptors, enhanced bioadhesion to cells, and cytocompatibility. Microgels represent one of such multifunctional drug delivery devices. Recently, we described the fabrication of a stable colloidal aqueous suspension of cytocompatible microgel spheres based on a poly(vinyl alcohol)/poly(methacrylate-co-N-isopropylacrylamide) network ( Ghugare, S. Mozetic, P. Paradossi, G. Biomacromolecules 2009 , 10 , 1589 ). These microgel spheres undergo an entropy-driven volume phase transition around the physiological temperature, this phase transition being driven by the incorporation of NiPAAm residues in the network. In that study, the microgel was loaded with the anticancer drug doxorubicin. As the microgel shrank, a marked increase in the amount of doxorubicin released was noted. Indeed, dynamic light scattering measurements showed the diameter reduction to be about 50%. In the present paper, we focus on some fundamental issues regarding modifications of the hydrogel architecture at a nanoscopic level as well as of the diffusive behavior of water associated with the polymer network around the volume phase transition temperature (VPTT). Sieving and size exclusion effects were studied by laser scanning confocal microscopy with the microgel exposed to fluorescent probes with different molecular weights. Confocal microscopy observations at room temperature and at 40 degrees C (i.e., below and above the VPTT) provided an evaluation of the variation of the average pore size (from 5 nm to less than 3 nm). Using quasielastic neutron scattering (QENS) with the IRIS spectrometer at ISIS, UK, the diffusive behavior of water molecules closely associated to the polymer network around the VPTT was investigated. A clear change in the values of diffusion coefficient of bound water was observed at the transition temperature. In addition, the local dynamics of the polymer itself was probed using the QENS spectrometer SPHERES at FRM II, Germany. For this study, the microgel was swollen in D(2)O. An average characteristic distance of about 5 A for the localized chain motions was evaluated from the elastic incoherent structure factor (EISF) and from the Q-dependence of the Lorentzian width