Person: López Cabarcos, Enrique
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First Name
Enrique
Last Name
López Cabarcos
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Farmacia
Department
Química en Ciencias Farmacéuticas
Area
Química Física
Identifiers
16 results
Search Results
Now showing 1 - 10 of 16
Item Enhancement of the Upconversion Emission by Visible-to-Near-Infrared Fluorescent Graphene Quantum Dots for miRNA Detection(ACS Applied Materials & Interfaces, 2016) Laurenti, Marco; Paez-Pérez, Miguel; Algarra González, Manuel; Alonso Cristobal, Paulino; López Cabarcos, Enrique; Méndez González, Diego; Rubio Retama, Benito JorgeWe developed a sensor for the detection of specific microRNA (miRNA) sequences that was based on graphene quantum dots (GQDs) and ssDNA-UCNP@SiO2. The proposed sensor exploits the interaction between the sp2 carbon atoms of the GQD, mainly π–π stacking, and the DNA nucleobases anchored on the upconversion nanoparticles (UCNPs). This interaction brings the GQD to the surface of the ssDNA-UCNP@SiO2 system, enhancing the upconversion emission. On the other hand, hybridization of the single-stranded DNA (ssDNA) chains anchored on the nanoparticles with their complementary miRNA sequences blocks the capacity of the UCNPs to interact with the GQD through π–π stacking. That gives as result a reduction of the fluorescent enhancement, which is dependent on the concentration of miRNA sequences. This effect was used to create a sensor for miRNA sequences with a detection limit of 10 fM.Item Oligonucleotide Sensor Based on Selective Capture of Upconversion Nanoparticles Triggered by Target Induced DNA Inter-Strand Ligand Reaction(ACS applied materials & interfaces, 2017) Méndez González, Diego; Laurenti, Marco; Latorre, Alfonso; Somoza, Álvaro; Vázquez, Ana; Negredo, Ana Isabel; López Cabarcos, Enrique; Calderón, Oscar Gómez; Melle Hernández, Sonia; Rubio Retama, JorgeWe present a sensor that exploits the phenomenon of upconversion luminescence to detect the presence of specific sequences of small oligonucleotides like miRNAs among others. The sensor is based on NaYF4:Yb,Er@SiO2 nanoparticles functionalized with ssDNA that contain azide groups on the 3' ends. In the presence of a target sequence, inter-strand ligation is possible via click-reaction between one azide of the upconversion probe and a DBCO-ssDNA-biotin probe present in the solution. As result of this specific and selective process, biotin is covalently attached to the surface of the upconversion nanoparticles. The presence of biotin on the surface of the nanoparticles allows their selective capture on a streptavidin-coated support, giving a luminescent signal proportional to the amount of target present in the test samples. With the aim of studying the analytical properties of the sensor, total RNA samples were extracted from healthy mosquitoes and spiked-in with a specific target sequence at different concentrations. The result of these experiments revealed that the sensor was able to detect 10-17 moles (100 fM) of the target sequence in mixtures containing 100 ng of total RNA per well. Similar limit of detection was found for spiked human serum samples, demonstrating its suitability for detecting specific sequences of small oligonucleotides under real conditions. By contrast, under the presence of non-complementary sequences or sequences having mismatches, the luminescent signal was negligible or conspicuously reduced.Item Control of upconversion luminescence by gold nanoparticle size: from quenching to enhancement(Nanoscale, 2019) Méndez González, Diego; Melle Hernández, Sonia; Gómez Calderón, Óscar; Laurenti, Marco; Cabrera Granado, Eduardo; Egatz-Gómez, Ana; López Cabarcos, Enrique; Rubio Retama, Jorge; Díaz García, ElenaMetallic nanostructures have the potential to modify the anti-Stokes emission of upconverting nanoparticles (UCNPs) by coupling their plasmon resonance with either the excitation or the emission wavelength of the UCNPs. In this regard gold nanoparticles (AuNPs) have often been used in sensors for UCNP luminescence quenching or enhancement, although systematic studies are still needed in order to design optimal UCNP–AuNP based biosensors. Amidst mixed experimental evidence of quenching or enhancement, two key factors arise: the nanoparticle distance and nanoparticle size. In this work, we synthesize AuNPs of different sizes to assess their influence on the luminescence of UCNPs. We find that strong luminescence quenching due to resonance energy transfer is preferentially achieved for small AuNPs, peaking at an optimal size. A further increase in the AuNP size is accompanied by a reduction of luminescence quenching due to an incipient plasmonic enhancement effect. This enhancement counterbalances the luminescence quenching effect at the biggest tested AuNP size. The experimental findings are theoretically validated by studying the decay rate of the UCNP emitters near a gold nanoparticle using both a classical phenomenological model and the finite-difference time-domain method. Results from this study establish general guidelines to consider when designing sensors based on UCNPs–AuNPs as donor–quencher pairs, and suggest the potential of plasmon-induced luminescence enhancement as a sensing strategy.Item FRET distance dependence from upconverting nanoparticles to quantum dots(Journal of physical chemistry C, 2018) Melle Hernández, Sonia; Gómez Calderón, Óscar; Laurenti, Marco; Méndez González, Diego; Egatz-Gómez, Ana; López Cabarcos, Enrique; Cabrera Granado, Eduardo; Díaz García, Elena; Rubio Retama, JorgeFörster resonant energy transfer (FRET) with upconverting nanoparticles (UCNPs) as donors and quantum dots (QDs) as acceptors has been regarded as a promising tool for biosensing applications. In this work, we use time-resolved fluorescence spectroscopy to analyze the UCNP-to-QD FRET and we focus on the most relevant parameter of the FRET phenomenon, UCNP-QD distance. This distance is controlled by a nanometric silica shell around the UCNP surface. We theoretically reproduce the experimental results applying FRET theory to the distribution of emitting erbium ions in the UCNP. This simple model allows us to estimate the contribution of every erbium ion to the final FRET response and to explore different strategies to improve FRET efficiency.Item Contribution of resonance energy transfer to the luminescence quenching of upconversion nanoparticles with graphene oxide(Journal of Colloid and Interface Science, 2020) Méndez González, Diego; Gómez Calderón, Óscar; Melle Hernández, Sonia; González Izquierdo, Jesús; Bañares Morcillo, Luis; López Díaz, David; Velazquez Salicio, M. Mercedes; López Cabarcos, Enrique; Rubio Retama, Benito Jorge; Laurenti, MarcoUpconversion 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.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 Bone augmentation in rabbit calvariae: comparative study between Bio-Oss® and a novel B-TCP/DCPD granulate(Journal of Clinical Periodontology, 2006) Tamimi, Faleh; Torres García-Denche, Jesús; Tresguerres, Isabel; Clemente, Celia; López Cabarcos, Enrique; Blanco Jerez, LuisAim: In the present in vivo study, we compare the bone regeneration capacity of a novel brushite cement synthesized in our laboratory (DTG) with Bio-Oss® using rabbits as an animal model. Methods: The study was performed in a group of 14 adult New Zealand rabbits using the bone conduction model. Two titanium cylinders were fixed into perforated slits made on the parietal cortical bone of each rabbit. One cylinder was left empty (negative control) and the other was filled with either Bio-Oss® or brushite set cement granules (test cylinder). Four weeks after the intervention, the animals were sacrified and biopsies were taken. The following parameters were analysed: bone tissue augmentation, bone mineral density and biomaterials resorption. The comparison of data between the different groups was performed using the Mann-Whitney test with a significance level of p<0.05. Results: The mean bone mineral density and augmented mineral tissue inside the test cylinders were similar but higher than those of negative controls. Material resorption and bone tissue augmentation were significantly higher in the defects treated with the brushite-based set cement (p<0.05). Conclusions: Brushite cement granules were more resorbable and generated more bone tissue than Bio-Oss® inside the titanium cylinders placed in the rabbit calvaria.Item Matrix tablets based on a novel poly (magnesium acrylate) hydrogel for the treatment of inflammatory bowel diseases(International journal of pharmaceutics, 2021) Simancas Herbada, Rebeca; Torres Suárez, Ana Isabel; Otero Espinar, Francisco; Fraguas Sánchez, Ana Isabel; López Cabarcos, Enrique; Rubio Retama, Jorge; Fernández Carballido, Ana MaríaThe objective of this work was to evaluate the potential use of a new polymer (PAMgA) in the development sustained release matrix tablets for the treatment of bowel inflammatory diseases. For this purpose, budesonide, a highly lipophilic compound, was used as model drug. Tablets with two reticulation grades of PAMgA (PAMgA 5 and 40) and with 9 mg of budesonide were developed and characterized. All the studies were carried out using biorelevant media (FaSSGF and FaSSIF). Swelling and erosion of PAMgA tablets was influenced by the reticulation grade of the polymer and the biorelevant media assayed, being water uptake higher for PAMgA 40 tablets in intestinal fluid, whereas PAMgA 5 showed more intense erosion in this biorelevant medium. Budesonide was released slowly from PAMgA tablets, both in gastric and intestinal environment, following Super case II transport kinetics (relaxation-controlled delivery), with a lag time of around 1–2 h. When the dissolution medium was changed sequentially throughout the trial, 75% of the budesonide dose was released in a sustained manner between 4 and 20 h of testing from PAMgA tablets, showing a more controlled budesonide release than Entocort® and Budenofalk® (commercially available sustained release formulations of budesonide). In conclusion, PAMgA polymer allows controlling the release of highly lipophilic drugs as budesonide, being an useful excipient for the development of sustained release matrix tablets.Item Strontium Ions Substitution in Brushite Crystals: The Role of Strontium Chloride(Journal of Functional Biomaterials, 2011) Alkhraisat, Mohammad H.; Rueda, Carmen; López Cabarcos, EnriqueThe incorporation of strontium chloride to brushite cement was successful to introduce strontium ions within the lattice of brushite crystals. The effect of strontium ions on brushite cement properties was concentration dependent; such that, the addition of 5% and 10% (w/w) SrCl2 significantly increased the cement FST and the addition of 10% SrCl2 decreased the cement tensile strength. Further, cement weight loss was shown to be increased by cement modification with SrCl2. The combination of ionic substitution and the degradability of brushite cements would constitute a system for the local delivery of strontium ions in the treatment of osteoporosis.- 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.