Examinando por Autor "Morales, V."

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Direct synthesis and post-oxidation of SBA-15 and MCM-41 functionalized with butenyl groups.
(ELSEVIER, 2005) Garcia, R.A.; van Grieken, R.; Iglesias, J.; Morales, V.; Martin, J.
Olefins and derivatives are interesting compounds to anchor onto the surface of silica supports since their reactivity allow to form a large variety of organic functionalities. In this work, the synthesis of mesostructured silicas (MCM 41 and SBA 15 type materials) functionalized with butenyl groups is studied through the use of post synthetic grafting or direct synthesis procedures. Results confirm the higher functionalization degree achieved in the final mesostructured materials when using direct synthesis procedures. Unlike MCM 41 materials, which become microporous when high organic content are attached on, SBA 15 type butenyl functionalized silicas keep the features of a mesoporous solid. Post synthetic and in-situ oxidations of butenyl groups during the preparation of the mesostructured silicas have been carried out using H2O2 as oxidant, leading to materials functionalized with glycol species attached to inorganic mesoporous materials, which are attractive to be used as supports for anchoring different catalytic species.
Effect of the dual incorporation of fullerene and polyethyleneimine moieties into SBA-15 materials as platforms for drug delivery
(Springer Nature, 2019-05-28) Martín, A.; Morales, V.; Ortiz-Bustos, J.; Sanz, R.; García-Muñoz, R.A.
Mesostructured SBA-15 silica materials have been successfully dual functionalized with polyethyleneimine (PEI) groups and C60 fullerene moieties to allow an evaluation of their properties as nanovehicles for controlled drug delivery. Methylprednisolone sodium succinate was selected as a model drug for adsorption on the surface of functionalized SBA-15 silica materials. The resulting dual-functionalized SBA-15 silica materials exhibit mesoscopic arrangements, although with a remarkable reduction in their textural properties as compared to pure silica SBA-15. The adsorption capacity of methylprednisolone on functionalized SBA-15-PEI improved remarkably compared with that of raw SBA-15, while the drug release rate slowed, as the amount of PEI anchored in the SBA-15 increased. The strong attractive electrostatic interactions between methylprednisolone and the silica surfaces of SBA-15-PEI materials, measured by zeta potential, account for these results. In a second step, wherein C60 fullerene species in combination with PEI were grafted to the silica, the results establish that the steric effects and hydrophobicity of the C60 moieties hinder methylprednisolone transport within the silica pores. The kinetic parameters obtained from the drug release profiles, fitted to four kinetic models, show that the incorporation of C60 species yields lower methylprednisolone release rates from SBA-15-PEI-C60 materials than from SBA-15-PEI materials. Additionally, the incorporation of fullerene groups into PEI-modified materials provides an increment in cell viability. Confocal microscopy evidences the cellular internalization of the dual-functionalized mesoporous SBA-15 materials inside the plasmatic membrane.
Modelling the adsorption and controlled release of drugs from the pure and amino surface-functionalized mesoporous silica hosts
(Elsevier, 2018-05-15) Martín, A.; Morales, V.; Ortiz-Bustos, J.; Pérez-Garnés, M.; Bautista, L.F.; García-Muñoz, R.A.
Several mesoporous silica materials with different structures were investigated as matrices for controlled drug delivery. The aim of this study is correlating the textural and surface chemical properties of these materials with the adsorption and delivery of the drug model methylprednisolone sodium succinate. The materials were synthesized according to different protocols, and employing both cationic and non-ionic surfactants. Additionally, the functionalization of the materials' surface with 1-[3-(trimethoxysilyl)propyl]diethylenetriamine (DT) was accomplished to study the synergistic effect of the incorporation of amine groups and textural properties on the loading and delivery of drug. The thermodynamics and dynamic adsorption behavior of these materials were determined and fitted to several isotherms models to provide information about the drug adsorption processes. The maximum adsorption capacities of the raw silica supports were correlated with the pore size and the results indicated that the drug adsorption ability improved as the material pore size increases. Moreover, it is observed that the drug adsorption on materials with mesoporous size higher than 10 nm are very close to the theoretical saturation capacity. Regarding amino-modified materials, isotherms models confirmed that the factor governing the adsorption process were mainly the electrostatic interactions, hydrogen bonding and/or hydrophobic-hydrophilic interactions between the drug moieties and amino-functionalized silica surfaces, and in a lesser degree the textural properties of the support. Furthermore, the kinetics of the drug release from these materials functionalized with amino groups were also modelled to finally obtain a correlation between the adsorption and release drug cargo from the host pure and surface-functionalized materials.
Synthesis and characterization of SBA-15 materials functionalized with olefinic groups and subsequent modification through oxidation procedures
(ELSEVIER, 2010) van Grieken, R.; Iglesias, J.; Morales, V.; García, R.A.
The synthesis of alkenyl-SBA-15 materials has been carried out through different methodologies. The direct-synthesis method used for the functionalization of SBA-15 involving the co-condensation of the alkenyl-silicon precursor together with silicon alkoxides is clearly superior than any other post-synthetic pathway, even if acid catalysts are used to drive the post-synthetic grafting of olefin groups. The direct-synthesis methodology has been deeply studied within this work, involving the influence of the silica precursor prehydrolysis time, and the loading of different olefin-silanes on the quality of the mesostructure. Small olefinic functionalities, like vinyl groups, can be incorporated in a very efficient manner up to achieve organic loadings as high as 50% mole of the olefin precursor to TEOS. The modification of these alkenyl groups through oxidation can be accomplished through post-synthetic oxidation of the olefinic group or even through an in-situ methodology where the oxidant ¿ hydrogen peroxide ¿ is added together with the rest of the precursor into the synthesis gel to lead complete oxidation of the double bonds towards glycolic functionalities. The resultant materials show potential as hydrophilic adsorbents and catalytic supports.