Open Access
Nanoporous alumina support covered by imidazole moiety-based ionic liquids: optical characterization and application
(MDPI, 2022) Algarra González, Manuel; López Escalante, María Cruz; Martínez de Yuso, María Valle; Soto, Juan; Cuevas, Ana L.; Benavente, Juana; Institute for Advanced Materials and Mathematics - INAMAT2
This work analyzes chemical surface and optical characteristics of a commercial nanoporous alumina structure (NPAS) as a result of surface coverage by different imidazolium-based ionic liquids (1-butyl-3-metylimidazolium hexafluorophosphate, 3-methyl-1-octylimidazolium hexafluorophosphate, or 1-ethyl-3-methylimidazolium tetrafluoroborate). Optical characteristics of the IL/NPAS samples were determined by photoluminescence (at different excitation wavelengths (from 300 nm to 400 nm), ellipsometry spectroscopy, and light transmittance/reflectance measurements for a range of wavelengths that provide information on modifications related to both visible and near-infrared regions. Chemical surface characterization of the three IL/NPAS samples was performed by X-ray photoelectron spectroscopy (XPS), which indicates almost total support coverage by the ILs. The IL/NPAS analyzed samples exhibit different photoluminescence behavior, high transparency (<85%), and a reflection maximum at wavelength ~380 nm, with slight differences depending on the IL, while the refractive index values are rather similar to those shown by the ILs. Moreover, the illuminated I–V curves (under standard conditions) of the IL/NPAS samples were also measured for determining the efficiency energy conversion to estimate their possible application as solar cells. On the other hand, a computational quantum mechanical modeling method (DFT) was used to establish the most stable bond between the ILs and the NPAS support.
Open Access
Multifunctionalized carbon dots as an active nanocarrier for drug delivery to the glioblastoma cell line
(American Chemical Society, 2024) Algarra González, Manuel; Soto, Juan; Pino-González, María Soledad; González-Muñoz, Elena; Dučić, Tanja; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Nanoparticle-based nanocarriers represent a viable alternative to conventional direct administration in cancer cells. This advanced approach employs the use of nanotechnology to transport therapeutic agents directly to cancer cells, thereby reducing the risk of damage to healthy cells and enhancing the efficacy of treatment. By approving nanoparticle-based nanocarriers, the potential for targeted, effective treatment is greatly increased. The so-called carbon-based nanoparticles, or carbon dots, have been hydrothermally prepared and initiated by a polymerization process. We synthesized and characterized nanoparticles of 2-acrylamido-2-methylpropanesulfonic acid, which showed biocompatibility with glioblastoma cells, and further, we tested them as a carrier for the drug riluzole. The obtained nanoparticles have been extensively characterized by techniques to obtain the exact composition of their surface by using Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (NMR) spectroscopy, as well as cryo-transmission electron microscopy. We found that the surface of the synthesized nanoparticles (NPs) is covered mainly by sulfonated, carboxylic, and substituted amide groups. These functional groups make them suitable as carriers for drug delivery in cancer cells. Specifically, we have successfully utilized the NPs as a delivery system for the drug riluzole, which has shown efficacy in treating glioblastoma cancer cells. The effect of nanoparticles as carriers for the riluzole system on glioblastoma cells was studied using live-cell synchrotron-based FTIR microspectroscopy to monitor in situ biochemical changes. After applying nanoparticles as nanocarriers, we have observed changes in all biomacromolecules, including the nucleic acids and protein conformation. These findings provide a strong foundation for further exploration into the development of targeted treatments for glioblastoma.
Embargo
Testing of black-carrots-derived fluorescence imaging and anti-metastatic potential
(Elsevier, 2024) Algarra González, Manuel; Carrillo, Celia; Nesic, Maja D.; Filipovic Trickovic, Jelena; Zakula, Jelena; Koricanac, Lela; Jiménez-Jiménez, José; Rodríguez-Castellón, Enrique; Bandosz, Teresa J.; Petkovic, Marijana; Soto, Juan; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
This paper explains the basis for the excitation energy-independent fluorescence emission of biomass-derived carbon dots (CDs) and shows that these CDs have excellent anti-melanoma and anti-metastatic potential. Additionally, we demonstrate that the black carrots´-derived CDs can be exploited as cell cycle-sensing agents, because of the interaction with chromatin material. Besides their optical properties, fluorescent CDs have gained increased attention for image-guided cancer treatment due to their water solubility, environmental friendliness, affordability, ease of synthesis, and primary biocompatibility. CDs have excellent photostability, determined by their precursors and synthesis pathways. In this study, CDs with chemically homogenous surface functional groups were made using a hydrothermal technique from black carrot extract, an anthocyanin-rich substance derived from biomass. The anti-cancer and anti-metastatic properties of black carrot-derived CDs can be attributed to flavylium cations on the surface, spherical forms, and high water dispersibility. Most importantly, these CDs demonstrate a stable emission at a single wavelength, 612 nm, independent of the excitation energy, which we have explained theoretically for the first time.
Open Access
CASPT2 study of the electronic structure and photochemistry of protonated N-nitrosodimethylamine (NDMA-H+) at 453 nm
(American Institute of Physics, 2023) Soto, Juan; Peláez, Daniel; Algarra González, Manuel; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
In this work, we have studied the photodissociation of the protonated derivatives of N-nitrosodimethylamine [(CH3)2N–NO] with the CASPT2 method. It is found that only one of the four possible protonated species of the dialkylnitrosamine compound absorbs in the visible region at 453 nm, that is, N-nitrosoammonium ion [(CH3)2NH-NO]+ . This species is also the only one whose first singlet excited state is dissociative to directly yield the aminium radical cation [(CH3)2NHN⋅] + and nitric oxide. In addition, we have studied the intramolecular proton migration reaction {[(CH3)2N–NOH] + → [(CH3)2NH–NO]+ } both in the ground and excited state (ESIPT/GSIPT); our results indicate that this process is not accessible neither in the ground nor in the first excited state. Furthermore, as a first approximation, MP2/HF calculations on the nitrosamine–acid complex indicate that in acidic solutions of aprotic solvents, only [(CH3)2NH–NO]+ is formed.
Open Access
UV-photoelectron spectroscopy and MS-CASPT2/CASSCF study of the thermolysis of azidoethyl-methyl sulfide: Characterization and mechanism of the formation of S-methyl-N-sulfenylethanimine
(American Institute of Physics (AIP), 2025-05-16) Algarra González, Manuel; Labat, Stephane; Rodríguez-Borges, José Enrique; Pino-González, María Soledad; Sotiropoulos, Jean Marc; Soto, Juan; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The thermal decomposition of azidoethyl methyl sulfide was studied by real-time UV-photoelectron spectroscopy (UV-PES) at temperatures ranging from 773 to 1023 K. Different ionization energies were obtained using density functional theory calculations to assign UV-PES spectra. The complete active space self-consistent field and multistate second-order perturbation methods were used to predict the formation of different species present in the thermal decomposition process. N2 and S-methyl-N-sulfenylethanimine are generated at 773 K. The first step of the reaction is the dissociation of the molecule into nitrene and nitrogen. The spin state (singlet or triplet) of nitrene formed in the first step of the reaction is temperature-dependent. At low temperatures (T ≤ 650 K), both states are formed with almost the same probability; in contrast, at high temperatures (T ≤ 1000 K), singlet nitrene is the majority intermediate. From this singlet nitrene, three stable reaction products were detected in the experiments: an imine derivative, a four-member cyclic derivative, and a sulfenyl derivative.
Open Access
Nitrene formation is the first step of the thermal and photochemical decomposition reactions of organic azides
(Royal Society of Chemistry, 2022) Soto, Juan; Algarra González, Manuel; Peláez, Daniel; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
In this work, the decomposition of a prototypical azide, isopropyl azide, both in the ground and excited states, has been investigated through the use of multiconfigurational CASSCF and MS-CASPT2 electronic structure approaches. Particular emphasis has been placed on the thermal reaction starting at the S0 ground state surface. It has been found that the azide thermally decomposes via a stepwise mechanism, whose rate-determining step is the formation of isopropyl nitrene, which is, in turn, the first step of the global mechanism. After that, the nitrene isomerizes to the corresponding imine derivative. Two routes are possible for such a decomposition: (i) a spin-allowed path involving a transition state; and (ii) a spinforbidden one via a S0/T0 intersystem crossing. Both intermediates have been determined and characterised. Their associated relative energies have been found to be quite similar, 45.75 and 45.52 kcal mol1, respectively. To complete this study, the kinetics of the singlet and triplet channels are modeled with the MESMER (Master Equation Solver for Multi-Energy Well Reactions) code by applying the RRKM and Landau Zener (with WKB tunnelling correction) theories, respectively. It is found that the canonical rate-coefficients of the singlet path are 2-orders of magnitude higher than the ratecoefficients of the forbidden reaction. In addition, the concerted mechanism has been investigated that would lead to the formation of the imine derivative and nitrogen extrusion in the first step of the decomposition. After a careful analysis of CASSCF calculations with different active spaces and their comparison with single electronic configuration methods (MP2 and B3LYP), the concerted mechanism is discarded.