Person: Contreras Cáceres, Rafael
Loading...
First Name
Rafael
Last Name
Contreras Cáceres
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Farmacia
Department
Química en Ciencias Farmacéuticas
Area
Identifiers
4 results
Search Results
Now showing 1 - 4 of 4
Item 10-Fold Quantum Yield Improvement of Ag2S Nanoparticles by Fine Compositional Tuning(ACS Applied materials and interfaces, 2020) Ortega Rodríguez, Alicia; Shen, Yingli; Zabala Gutiérrez, Irene; Santos, Harrison D. A.; Torres Vera, Vivian Andrea; Ximedes, Erving; Villaverde Cantizano, Gonzalo; Lifante, José; Gerke, Christoph; Fernández Monsalve, Nuria; Gómez Calderón, Óscar; Melle Hernández, Sonia; Marqués Hueso, José; Méndez González, Diego; Laurenti, Marco; Jones, Callum M. S.; López Romero, Juan Manuel; Contreras Cáceres, Rafael; Jaque García, Daniel; Rubio Retama, Benito Jorge; Garma Pons, SantiagoAg2S 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. .Item The effects of dopant concentration and excitation intensity on the upconversion and downconversion emission processes of β-NaYF4:Yb3+,Er3+nanoparticles(Journal of materials chemistry C, 2021) Torres Vera, Vivian Andrea; Méndez González, Diego; Ramos Ramos, D. J.; Igalla El-Youssfi, Asmae; Laurenti, Marco; Contreras Cáceres, Rafael; López Cabarcos, Enrique; Díaz García, Elena; Rubio Retama, Benito Jorge; Melle Hernández, Sonia; Gómez Calderón, ÓscarThe dopant concentration of lanthanide ions in photon upconversion nanoparticles (UCNPs) remains one of the key points to boost the brightness of these nanomaterials and, therefore, their application developments. Here, we analyzed the effect of Er3+ and Yb3+ dopant concentrations of b-NaYF4:Yb3+,Er3+ nanoparticles on the visible upconversion and near-infrared downconversion luminescence intensities. Our approach carefully excluded all other factors whose variation affects luminescence properties such as the size, morphology, crystal structure, ion distribution, ligand, and surrounding medium, allowing us to exactly infer the influence of the ratio of Yb3+ to Er3+ ions on the nanoparticle luminescence. To maintain the size and morphological properties of nanoparticles, we used a total dopant concentration of 22% while varying the ratio of Yb3+ to Er3+ ions from 0 to 10. A huge increase in luminescence takes place as the Yb/Er ratio increases following a power-law behavior, and this luminescence enhancement is greater at low excitation intensities. Above a Yb/Er ratio of around two, saturation occurs with a slight peak when this ratio is around four. Simulations using a rate equation model showed that upconversion luminescence (UCL) is mainly produced by the energy transfer between neighboring Er3+ ions at low Yb/Er ratios, while at high ratios, the energy transfer from Yb3+ to Er3+ ions dominates. However, downconversion luminescence (DCL) is produced at all analyzed ratios, except 0, by the previous mechanism.Item SPION nanoparticles for delivery of dopaminergic isoquinoline and benzazepine derivatives(Bioorganic & Medicinal Chemistry, 2022) Lucena-Serrano, Cristina; Lucena-Serrano, Ana; Díaz, Amelia; Valpuesta, María; Villaverde Cantizano, Gonzalo; López-Romero, J. Manuel; Sarabia, Francisco; Laurenti, Marco; Rubio Retama, Benito Jorge; Contreras Cáceres, RafaelSuperparamagnetic 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.- Project number: 74
Item Las TICs: un instrumento de ayuda en las prácticas de laboratorio(2022) Laurenti, Marco; Ovejero Paredes, Karina; Zabala Gutiérrez, Irene; Sanchez Sanche, Visitación; Yusta San Roman, Piedad; Contreras Cáceres, Rafael; Filice, Marco; López Cabarcos, Enrique; Marciello, Marzia; Méndez González, Diego; Rubio Retama, Benito Jorge; Villaverde Cantizano, GonzaloDesde 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.