Open Access
Steering the synthesis of Fe3O4 nanoparticles under sonication by using a fractional factorial design
(Elsevier, 2021) Echeverría Morrás, Jesús; Moriones Jiménez, Paula; Garrido Segovia, Julián José; Ugarte Martínez, María Dolores; Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Superparamagnetic iron oxide nanoparticles (MNPs) have the potential to act as heat sources in magnetic hyperthermia. The key parameter for this application is the specific absorption rate (SAR), which must be as large as possible in order to optimize the hyperthermia treatment. We applied a Plackett-Burman fractional factorial design to investigate the effect of total iron concentration, ammonia concentration, reaction temperature, sonication time and percentage of ethanol in the aqueous media on the properties of iron oxide MNPs. Characterization techniques included total iron content, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, High Resolution Transmission Electron Microscopy, and Dynamic Magnetization. The reaction pathway in the coprecipitation reaction depended on the initial Fe concentration. Samples synthesized from 0.220 mol L−1 Fe yielded magnetite and metastable precipitates of iron oxyhydroxides. An initial solution made up of 0.110 mol L−1 total Fe and either 0.90 or 1.20 mol L−1 NH3(aq) led to the formation of magnetite nanoparticles. Sonication of the reaction media promoted a phase transformation of metastable oxyhydroxides to crystalline magnetite, the development of crystallinity, and the increase of specific absorption rate under dynamic magnetization.
Open Access
Tunability of hybrid silica xerogels: surface chemistry and porous texture based on the aromatic precursor
(MDPI, 2023) Rosales Reina, María Beatriz; Cruz Quesada, Guillermo; Padilla-Postigo, Nataly; Irigoyen-Razquin, Marian; Alonso-Martínez, Ester; López Ramón, María Victoria; Espinal Viguri, Maialen; Garrido Segovia, Julián José; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The interest in new materials with specific properties has increased because they are essential for the environmental and technological needs of our society. Among them, silica hybrid xerogels have emerged as promising candidates due to their simple preparation and tunability: when they are synthesised, depending on the organic precursor and its concentration, their properties can be modulated, and thus, it is possible to prepare materials with à la carte porosity and surface chemistry. This research aims to design two new series of silica hybrid xerogels by co-condensation of tetraethoxysilane (TEOS) with triethoxy(p-tolyl)silane (MPhTEOS) or 1,4-bis(triethoxysilyl)benzene (Ph(TEOS)2 and to determine their chemical and textural properties based on a variety of characterisation techniques (FT-IR, 29Si NMR, X-ray diffraction and N2 , CO2 and water vapour adsorption, among others). The information gathered from these techniques reveals that depending on the organic precursor and its molar percentage, materials with different porosity, hydrophilicity and local order are obtained, evidencing the easy modulation of their properties. The ultimate goal of this study is to prepare materials suitable for a variety of applications, such as adsorbents for pollutants, catalysts, films for solar cells or coatings for optic fibre sensors.
Open Access
Hybrid xerogels doped with Tb(III) and Eu (III) and a water soluble Pybox ligand
(2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Hybrid organic-inorganic siliceous materials (ORMOSiLs) are a key focus within the nanoscience area as they combine advantages of inorganic materials without losing characteristics intrinsic of organic molecules. In the past years, our research group has designed hybrid siliceous xerogels (HSXG) with porosities and surface chemistries on demand for a range of applications, such as coatings for optic fiber sensors [1]. Although hybrid xerogels are mainly amorphous materials, recent studies by our group have demonstrated that introducing specific organic fragments on the precursors can induce selforganization during the sol-gel process to obtain a series of transparent nanostructured HSXG [2]. In the present work, a step forward is taken in the applicability of this type of HSXG by doping them with Tb(III) or Eu (III) cations and a water-soluble pybox-based antenna ligand (Pybox-EG= 2,2′-(4-(2-Ethoxyethoxy)pyridine-2,6-diyl)bis(4,5-dihydrooxazole)). Inclusion of photoluminescence will provide the materials with new properties and therefore new applications in fiber optic sensors (FOS) or in solar cells devices.
Open Access
New hybrid organochlorinated xerogels
(2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Hybrid silica xerogels (HSXG) combine the properties of organic and inorganic components in the same material, which makes them promising and versatile candidates for multiple applications. These materials can be easily prepared by the sol-gel process, which offers the possibility to obtain different morphologies. The incorporation of organic precursors plays an important role in their properties, hence, allowing the design of materials for specific applications such as coatings for optical fibers [1]. The aim of this work was to study the influence of the alkyl chain and chlorine atom on the morphological and textural properties of various hybrid materials produced by co-condensation. For this purpose, three series of hybrid xerogels were prepared by co-condensation of TEOS and a chloroalkyltriethoxysilane (TEOS:ClRTEOS, R = methyl, ethyl or propyl) at different molar ratios. The influence of the precursors on the structure and textural properties of the xerogels was studied by means of N2 adsorption, XRD (X-ray diffraction), 29Si NMR (nuclear magnetic resonance) and FE-SEM (Field Emission-scanning electron microscope) [2].
Open Access
Hybrid xerogels: study of the sol-gel process and local structure by vibrational spectroscopy
(MDPI, 2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The properties of hybrid silica xerogels obtained by the sol-gel method are highly dependent on the precursor and the synthesis conditions. This study examines the influence of organic substituents of the precursor on the sol-gel process and determines the structure of the final materials in xerogels containing tetraethyl orthosilicate (TEOS) and alkyltriethoxysilane or chloroalkyltri-ethoxysilane at different molar percentages (RTEOS and ClRTEOS, R = methyl [M], ethyl [E], or propyl [P]). The intermolecular forces exerted by the organic moiety and the chlorine atom of the precursors were elucidated by comparing the sol-gel process between alkyl and chloroalkyl series. The microstructure of the resulting xerogels was explored in a structural theoretical study using Fourier transformed infrared spectroscopy and deconvolution methods, revealing the distribution of (SiO)4 and (SiO)6 rings in the silicon matrix of the hybrid xerogels. The results demonstrate that the alkyl chain and the chlorine atom of the precursor in these materials determines their inductive and steric effects on the sol-gel process and, therefore, their gelation times. Furthermore, the distribution of (SiO)4 and (SiO)6 rings was found to be consistent with the data from the X-ray diffraction spectra, which confirm that the local periodicity associated with four-fold rings increases with higher percentage of precursor. Both the sol-gel process and the ordered domains formed determine the final structure of these hybrid materials and, therefore, their properties and potential applications.
Open Access
Photocatalytic enhancement of anatase supported on mesoporous modified silica for the removal of carbamazepine
(MDPI, 2025-10-08) Cruz Quesada, Guillermo; Rosales Reina, María Beatriz; Velo-Gala, Inmaculada; Fernández-Poyatos, María del Pilar; Álvarez-Merino, Miguel Ángel; García-Ruiz, Cristian; López Ramón, María Victoria; Garrido Segovia, Julián José; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
TiO2 is the most used material for the photocatalytic removal of organic pollutants in aqueous media. TiO2, specifically its anatase phase, is well-known for its great performance under UV irradiation, high chemical stability, low cost and non-toxicity. Nevertheless, TiO2 presents two main drawbacks: its limited absorption of the visible spectrum; and its relatively low specific surface area and pore volume. Regarding the latter, several works in the literature have addressed the issue by developing new synthesis approaches in which anatase is dispersed and supported on the surface of porous materials. In the present work, two series of materials have been prepared where anatase has been supported on mesoporous silica (MSTiR%) in situ through a hydrothermal synthesis approach, where, in addition to using tetraethoxysilane (TEOS) as a silicon precursor, three organotriethoxysilanes [RTEOS, where R = methyl (M), propyl (P) or phenyl (Ph)] were used at a RTEOS:TEOS molar percentage of 10 and 30%. The materials were thoroughly characterized by several techniques to determine their morphological, textural, chemical, and UV-vis light absorption properties and then the most promising materials were used as photocatalysts in the photodegradation of the emerging contaminant and antiepileptic carbamazepine (CBZ) under UV irradiation. The materials synthesized using 10% molar percentage of RTEOS (MSTiR10) were able to almost completely degrade (~95%), 1 mg L−1 of CBZ after 1 h of irradiation using a 275 nm LED and 0.5 g L−1 of catalyst dose. Therefore, this new synthesis approach has proven useful to develop photoactive TiO2 composites with enhanced textural properties.
Open Access
The narrative of a line of research from a feminist perspective: fiber optic sensors and actor-network theory (ANT)
(MDPI, 2022) Aliende Urtasun, Ana; Garrido Segovia, Julián José; Soziologia eta Gizarte Lana; Institute for Advanced Materials and Mathematics - INAMAT2; Sociología y Trabajo Social
The narrative of a line of research from a feminist perspective involves describing the situated practices that contribute to understanding inequality in the construction of the social relationships that build links between human and nonhuman materialities. This paper aims to link feminist epistemology and actor–network theory to the expert network that produces, sustains and manages the design of the chemical zone of a fiber optic sensor (FOS) and of new smart materials, tracing the path of a university research group with important scientific publications that has also developed a line of work in the field of science, technology and society (STS). We are interested in the generalized division of labor and the role of science and technology in the creation of symbols in our culture, particularly in the field of expert knowledge, where research carried out by men and women constructs trajectories of academic success that are predominantly male. The transversal incorporation of gender analysis into the production of FOSs helps reveal the processes that have, up to this point, excluded women from prominent positions in publications. © 2022 by the authors.
Open Access
Fe3O4-SiO2 mesoporous core/shell nanoparticles for magnetic field-induced ibuprofen-controlled release
(American Chemical Society, 2022-12-23) García Rodríguez, Lucía; Garayo Urabayen, Eneko; López Ortega, Alberto; Galarreta Rodríguez, Itziar; Cervera Gabalda, Laura María; Cruz Quesada, Guillermo; Cornejo Ibergallartu, Alfonso; Garrido Segovia, Julián José; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA2020; Gobierno de Navarra / Nafarroako Gobernua
Hybrid magnetic nanoparticles made up of an iron oxide, Fe3O4, core and a mesoporous SiO2 shell with high magnetization and a large surface area were proposed as an efficient drug delivery platform. The core/shell structure was synthesized by two seed-mediated growth steps combining solvothermal and sol—gel approaches and using organic molecules as a porous scaffolding template. The system presents a mean particle diameter of 30(5) nm (9 nm magnetic core diameter and 10 nm silica shell thickness) with superparamagnetic behavior, saturation magnetization of 32 emu/g, and a significant AC magnetic-field-induced heating response (SAR = 63 W/gFe3O4, measured at an amplitude of 400 Oe and a frequency of 307 kHz). Using ibuprofen as a model drug, the specific surface area (231 m2/g) of the porous structure exhibits a high molecule loading capacity (10 wt %), and controlled drug release efficiency (67%) can be achieved using the external AC magnetic field for short time periods (5 min), showing faster and higher drug desorption compared to that of similar stimulus-responsive iron oxide-based nanocarriers. In addition, it is demonstrated that the magnetic field-induced drug release shows higher efficiency compared to that of the sustained release at fixed temperatures (47 and 53% for 37 and 42 °C, respectively), considering that the maximum temperature reached during the exposure to the magnetic field is well below (31 °C). Therefore, it can be hypothesized that short periods of exposure to the oscillating field induce much greater heating within the nanoparticles than in the external solution.
Open Access
Design of novel photoactive modified titanium silicalites and their application for venlafaxine degradation under simulated solar irradiation
(Wiley, 2024) Cruz Quesada, Guillermo; Sampaio, María J.; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Silva, Cláudia G.; Faria, Joaquim L.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA18-2022
Titanium silicalites (TS) are well-known materials for their use in industrial oxidation reactions, and although they are used as photocatalysts, their activity is limited. Therefore, numerous synthetic strategies are investigated to improve their photocatalytic activity. Herein, three series of modified titanium silicalites are synthesized using three different organotriethoxysilanes at different molar percentages with the aim of modifying the structure of the zeolite, both at a porous and chemical level, to obtain materials with high photocatalytic activity. The study of their morphological, textural, chemical, and UV–vis light absorption properties through various characterization techniques has allowed the selection of the best candidates to test their photoactivity in the degradation of venlafaxine, an antidepressant drug that persists as a contaminant in wastewater and has serious neurotoxic effects. Materials synthesized using a 5% molar percentage of RTEOS and 10% of PhTEOS (Ph = phenyl) are able to degrade venlafaxine, whereas the reference material does not show any photocatalytic activity. These results lead the way to use this synthetic strategy to develop titanium silicates and optimize their photocatalytic activity in degradation reactions of different pollutants.
Open Access
Determination of hazardous vapors from the thermal decomposition of organochlorinated silica xerogels with adsorptive properties
(Elsevier, 2024) Rosales Reina, María Beatriz; Cruz Quesada, Guillermo; Pujol, Pablo; Reinoso, Santiago; Elosúa Aguado, César; Arzamendi Manterola, Gurutze; López Ramón, María Victoria; Garrido Segovia, Julián José; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The incorporation of organic groups into sol-gel silica materials is known to have a noticeable impact on the properties and structure of the resulting xerogels due to the combination of the properties inherent to the organic fragments (functionality and flexibility) with the mechanical and structural stability of the inorganic matrix. However, the reduction of the inorganic content in the materials could be detrimental to their thermal stability properties, limiting the range of their potential applications. Therefore, this work aims to evaluate the thermal stability of hybrid inorganic-organic silica xerogels prepared from mixtures of tetraethoxysilane and organochlorinated triethoxysilane precursors. To this end, a series of four materials with a molar percentage of organochlorinated precursor fixed at 10%, but differing in the type of organic group (chloroalkyls varying in the alkyl-chain length and chlorophenyl), has been selected as model case study. The gases and vapors released during the thermal decomposition of the samples under N2 atmosphere have been analyzed and their components determined and quantified using a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrophotometer and to a gas chromatography-mass spectrometry unit. These analyses have allowed to identify up to three different thermal events for the pyrolysis of the organochlorinated xerogel materials and to elucidate the reaction pathways associated with such processes. These mechanisms have been found to be strongly dependent on the specific nature of the organic group.