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Rare-earth doped nanoparticles (RENPs) are attracting increasing interest in materials science due to their optical, magnetic, and chemical properties. RENPs can emit and absorb radiation in the second biological window (NIR-II, 1000-1400 nm) making them ideal optical probes for photoluminescence (PL) in vivo imaging. Their narrow emission bands and long PL lifetimes enable autofluorescence-free multiplexed imaging. Furthermore, the strong temperature dependence of the PL properties of some of these RENPs makes remote thermal imaging possible. This is the case of neodymium and ytterbium co-doped NPs that have been used as thermal reporters for in vivo diagnosis of, for instance, inflammatory processes. However, the lack of knowledge about how the chemical composition and architecture of these NPs influence their thermal sensitivity impedes further optimization. To shed light on this, we have systematically studied their emission intensity, PL decay time curves, absolute PL quantum yield, and thermal sensitivity as a function of the core chemical composition and size, active-shell, and outer-inert-shell thicknesses. The results revealed the crucial contribution of each of these factors in optimizing the NP thermal sensitivity. An optimal active shell thickness of around 2 nm and an outer inert shell of 3.5 nm maximize the PL lifetime and the thermal response of the NPs due to the competition between the temperature-dependent back energy transfer, the surface quenching effects, and the confinement of active ions in a thin layer. These findings pave the way for a rational design of RENPs with optimal thermal sensitivity., Comunidad de Madrid (España), Universidad Complutense de Madrid (España), Ministerio de Ciencia e Innovación de España, European Commission- Horizon 2020, Banco Santander (España), Depto. de Óptica, Depto. de Química en Ciencias Farmacéuticas, Fac. de Óptica y Optometría, Fac. de Farmacia, TRUE, pub

Silver chalcogenide semiconductor nanocrystals (Ag2E SNCs) have become a household name in the biomedical field, where they are used as contrast agents in bioimaging, photothermal therapy agents, and luminescent nanothermometers. The prominent position they have come to occupy in this field stems from a unique combination of features, above all near-infrared excitation and emission alongside low cytotoxicity. However, the first reports on Ag2E SNCs showed that a great limitation of these luminescent nanomaterials resided in their low photoluminescence quantum yield, which results in reduced brightness: a crippling feature in bioimaging and biosensing. In this article, we provide an overview of the strategies developed to overcome this hurdle. These strategies aim to remedy the presence of defects in the SNC core and/or surface, the presence of metallic silver, and off-stoichiometric composition. These features stem from the high mobility and redox potential of Ag+ ions, alongside the difficulty in controlling the nucleation and growth rate of Ag2E SNCs. The effectiveness of each approach is discussed. Lastly, a perspective on future research efforts to make Ag2E SNCs even brighter – and thus more effective in biomedical applications – is provided, with the hope of inspiring further investigation on these nanomaterials with a rich, complex set of physicochemical and spectroscopic properties., Ministerio de Ciencia, Innovación y Universidades (España), Instituto de Salud Carlos III, Comunidad de Madrid, Universidad Complutense de Madrid, Banco Santander, China Scholarship Council, Depto. de Óptica, Fac. de Óptica y Optometría, TRUE, pub

Upconversion nanoparticles (UCNP) are increasingly used due to their advantages over conventional fluorophores, and their use as resonance energy transfer (RET) donors has permitted their application as biosensors when they are combined with appropriate RET acceptors such as graphene oxide (GO). However, there is a lack of knowledge about the design and influence that GO composition produces over the quenching of these nanoparticles that in turn will define their performance as sensors. In this work, we have analysed the total quenching efficiency, as well as the actual values corresponding to the RET process between UCNPs and GO sheets with three different chemical compositions. Our findings indicate that excitation and emission absorption by GO sheets are the major contributor to the observed luminescence quenching in these systems. This challenges the general assumption that UCNPs luminescence deactivation by GO is caused by RET. Furthermore, RET efficiency has been theoretically calculated by means of a semiclassical model considering the different nonradiative energy transfer rates from each Er3+ ion to the GO thin film. These theoretical results highlight the relevance of the relative positions of the Er3+ ions inside the UCNP with respect to the GO sheet in order to explain the RET-induced efficiency measurements., Ministerio de Economía, Comercio y Empresa (España), Ministerio de Ciencia, Innovación y Universidades (España), Comunidad de Madrid, Universidad Complutense de Madrid/Banco de Santander, Fondos estructurales de la Unión Europea, Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, inpress

Ag2S semiconductor nanoparticles (NPs) are near-infrared luminescent probes with outstanding properties (good biocompatibility, optimum spectral operation range, and easy biofunctionalization) that make them ideal probes for in vivo imaging. Ag2S NPs have, indeed, made possible amazing challenges including in vivo brain imaging and advanced diagnosis of the cardiovascular system. Despite the continuous redesign of synthesis routes, the emission quantum yield (QY) of Ag2S NPs is typically below 0.2%. This leads to a low luminescent brightness that avoids their translation into the clinics. In this work, an innovative synthetic methodology that permits a 10-fold increment in the absolute QY from 0.2 up to 2.3% is presented. Such an increment in the QY is accompanied by an enlargement of photoluminescence lifetimes from 184 to 1200 ns. The optimized synthetic route presented here is based on a fine control over both the Ag core and the Ag/S ratio within the NPs. Such control reduces the density of structural defects and decreases the nonradiative pathways. In addition, we demonstrate that the superior performance of the Ag2S NPs allows for high-contrast in vivo bioimaging. ., Unión Europea, Ministerio de Economía, Comercio y Empresa (España), Comunidad de Madrid, Universidad Complutense de Madrid/Banco de Santander, Fundación para el Futuro de Colombia Colfuturo, Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, pub

Luminescence nanothermometry allows measuring temperature remotely and in a minimally invasive way by using the luminescence signal provided by nanosized materials. This technology has allowed, for example, the determination of intracellular temperature and in vivo monitoring of thermal processes in animal models. However, in the biomedical context, this sensing technology is crippled by the presence of bias (cross-sensitivity) that reduces the reliability of the thermal readout. Bias occurs when the impact of environmental conditions different from temperature also modifies the luminescence of the nanothermometers. Several sources that cause loss of reliability have been identified, mostly related to spectral distortions due to interaction between photons and biological tissues. In this work, we unveil an unexpected source of bias induced by metal ions. Specifically, we demonstrate that the reliability of Ag2S nanothermometers is compromised during the monitoring of photothermal processes produced by iron oxide nanoparticles. The observed bias occurs due to the heat-induced release of iron ions, which interact with the surface of the Ag2S nanothermometers, enhancing their emission. The results herein reported raise a warning to the community working on luminescence nanothermometry, since they reveal that the possible sources of bias in complex biological environments, rich in molecules and ions, are more numerous than previously expected., Ministerio de Ciencia en Innovación (España), Depto. de Óptica, Depto. de Química en Ciencias Farmacéuticas, Fac. de Óptica y Optometría, Fac. de Farmacia, TRUE, pub

Superparamagnetic iron nanoparticles (SPIONs) have become one of the most useful colloidal systems in nanomedicine. We report here the preparation of new hybrid core@shell systems based on SPION nanoparticles coated with a SiO2 shell (SPION@SiO2) and functionalized with carboxyl groups SPION@SiO2-COOH). A series of new N-alkylamino- and N-alkylamido-terminated 1-phenyl- tetrahydroisoquinolines (THIQs) and 3 tetrahydrobenzazepines (THBs) derivatives presenting -SMe and -Cl groups, respectively, with potential dopaminergic activity, are synthesized and incorporated to the hybrid system. We include the synthetic details for THIQs and THBs derivatives preparation and investigate the influence of the terminal-functional group as well as the number of carbon atoms linked to THIQ and THB molecules during the coupling to the SPION@SiO2-COOH. Nuclear magnetic resonance (NMR) and electron ionization mass spectrometry (EI-MS) are used to characterize the synthesized THIQs and THBs. High-angle annular dark-field transmission electron microscopy (HAADFTEM), energy dispersive X-ray transmission electron microscopy (EDX-TEM), and proton high-resolution magic angle spinning NMR spectroscopy1 H HRMAS-NMR) are used to confirm the presence of THB and THIQ molecules onto the surface of the nanoparticles. The hybrid SPION@SiO2-THIQ and THB systems show significant activity toward the D2 receptor, reaching Ki values of about 20 nM, thus having potential application in the treatment of central nervous system (CNS) diseases., Comunidad de Madrid, Ministerio de Ciencia, Innovación y Universidades (España), Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

Desde la implantación del Espacio Europeo de Educación Superior nos encontramos ante dos grandes retos; el desarrollo metodológico y tecnológico en la formación y docencia on-line y en segundo lugar la cada vez más elevada especialización requerida a los estudiantes durante el Grado y Doble Grado en Farmacia. Esto hace que el foco de la formación de los estudiantes se desvíe de los conocimientos básicos y competencias de formación tanto en el trabajo experimental como en el conocimiento teórico. El proyecto se encuadra en el marco de la asignatura obligatoria Física Aplicada a Farmacia de Grado y Doble Grado en Farmacia, unas carreras con una elevada carga práctica y experimental.

Desde la implantación del Espacio Europeo de Educación Superior nos encontramos ante dos grandes retos; el desarrollo metodológico y tecnológico en la formación y docencia on-line y en segundo lugar la cada vez más elevada especialización requerida a los estudiantes durante el Grado y Doble Grado en Farmacia. Esto hace que el foco de la formación de los estudiantes se desvíe de los conocimientos básicos y competencias de formación tanto en el trabajo experimental como en el conocimiento teórico. El proyecto se encuadra en el marco de la asignatura obligatoria Física Aplicada a Farmacia de Grado y Doble Grado en Farmacia, unas carreras con una elevada carga práctica y experimental.

In this work, we present a simple methodology to produce multi-responsive Janus nanoparticles using a Pickering emulsion-based approach. In order to use these nanoparticles (NPs) as emulsion stabilizers, tetrahydrofuran was physisorbed on the surface of freshly synthesized Fe3O4@SiO2 NPs, which reduced their inherent hydrophilic character and permitted to create a close packed arrangement of particles at the emulsion interface. This situation allowed selective functionalization of the surface of the nanoparticles exposed to the water phase with a vinyl derivate molecule, which permitted to initiate the sequential polymerization of pNIPAM and poly(vinylimidazole). Thus, we obtained Janus nanoparticles that responded to changes in the temperature and the pH of the media as well as to external magnetic fields. The presented method does not require the surface modification of the original nanoparticles with surfactants or the use of fused silica and provides an easy way to create Janus particles in the nanoscale range., Ministerio de Educación, Cultura y Deporte (España), MCGL&JAMA Foundation, Ministerio de Economía, Comercio y Empresa (España), Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub