Characterization of imprinted microbeads synthesized via minisuspension polymerization

The properties of MIPs synthesized by minisuspension polymerization are studied. The template is cyclododecyl 2,4-dihydroxybenzoate (1), which behaves as good mimic of the estrogenic mycotoxin zearalenone. 2-DAEM and EGDMA are used as functional and crosslinker monomers, respectively. The synthesized particles are characterized by optical and electronic microscopy, N2 sorption measurements, and FT-IR spectroscopy. The molecular recognition capability of MIPs is evaluated by comparing the adsorption Freundlich isotherms of MIPs to those of the corresponding non-imprinted polymers. It is concluded that MSP is an attractive alternative for molecular imprinting because it is easy to apply and produces high yield of spherical particles of tunable size with acceptable molecular recognition capabilities.Fil: Torres, Juan Jose. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Montejano, Hernan Alfredo. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Simple procedures for analyzing and purifying methylene green

Methylene green is a versatile dye that can be used in a wide range of technical applications, most of which require the dye to be pure. Because commercial lots of methylene green are known to be heterogeneous, we report a thin layer chromatographic method for checking purity. We also describe a simple and effective flash chromatographic purification procedure for subsequent purification. The identity and purity of the dye can be checked easily using UV-visible absorption spectrum measurements or by more sophisticated procedures if necessary. © 2012 The Biological Stain Commission.Fil: Glusko, Carlos Abel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Previtali, Carlos Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Montejano, Hernan Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

Quenching of the triplet state of safranine-O by aliphatic amines in AOT reverse micelles studied by transient absorption spectroscopy

The photophysics of Safranine-O (3,6-diamino-2,7-dimethyl-5 phenyl phenazinium chloride) (SfH+Cl-) was investigated in reverse micelles (RMs) of AOT  (sodium bis(2-ethylhexyl) sulfosuccinate) with special emphasis on the triplet state processes. The excited singlet state properties were measured by absorption and fluorescence spectroscopy. Steady state anisotropy was also measured as a function of the water content. All the measurements indicate that the dye is localized in the interface, sensing a medium of polarity similar to EtOH:water (3:1) mixtures. The triplet is formed in its monoprotonated form, independently of the pH of the water used to prepare the RMs. The  maximum of the T-T absorption spectrum in RMs confirms this conclusion. The triplet lifetime is much longer in AOT RMs than in homogeneous organic solvents. The intersystem crossing quantum yields are similar to those in organic solvents. A remarkable difference is observed in the quenching by aliphatic amines, while the quenching by the hydrophobic tributylamine is similar to that in methanol, the hydro-soluble triethanolamine is one order of magnitude more effective in RMs than in homogeneous solution. In the latter case  the quenching process is interpreted by a very fast intramicellar quenching, the overall kinetics being controlled by the exchange of amine molecules between RMs. Semireduced dye is formed in the quenching process in RMs in the di-protonated state with a comparable quantum yield to the monoprotonated state formed in homogeneous solvents. The results point to the advantage of the reverse micellar system for the generation of active radicals for the initiation of vinyl polymerization, since a much lower concentration of amine can be employed with similar quantum yields.Fil: Porcal, Gabriela Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Chesta, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Biasutti, Maria Alicia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Previtali, Carlos Mario. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Amplified singlet oxygen generation in metallated-porphyrin doped conjugated polymer nanoparticles

We report on the mechanism and efficiencies of singlet oxygen O2(1Δg) generation of nanoparticles (NP) of the conjugated polymer (CP) poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) doped with platinum octaethylporphyrin (PtOEP) suspended in water. A detailed study of the photophysics of these NP, using stationary and time-resolved absorption and emission techniques, indicates that O2(1Δg) is generated by the triplet excited state of F8BT and not by that of PtOEP, as previously observed for other porphyrin doped CP NP. O2(1Δg) quantum yields (ΦΔ) were measured by quantifying the characteristic phosphorescence of O2(1Δg) in the NIR region (∼1268 nm). It was found that incorporation of relatively small amounts of PtOEP to F8BT NP results in a significant increase of ΦΔ. NP containing 10% PtOEP (w/w) show a ΦΔ ∼ 0.24, which is 3 times larger than that observed for undoped F8BT NP, and larger than the reported for most water-soluble porphyrins. ΦΔ were also calculated from the oxidation rates (v0) of 3-[10-(2-carboxyethyl)anthracen-9-yl]propanoic acid (ADPA), a well-known chemical O2(1Δg) trap. Unexpectedly, this method was found to significantly overestimate the ΦΔ values due to the adsorption of ADPA on the surface of NP. The ADPA/NP adsorption process was characterized using a simple adsorption model yielding an (average) equilibrium constant of ∼8 × 103 M−1 and an (average) number of NP-binding sites of ∼14000. These results necessarily caution about the use of ADPA as a probe to evaluate ΦΔ in these NP systems. In addition, the interaction of F8BT NP with other anionic, cationic and zwitterionic dyes (dissolved in water) was studied. It was found that even at nano-molar concentrations all the dyes efficiently adsorb on the NP surface. This general and simple self-assembly strategy can be used to prepare superficially-dye-doped CP NP with potentially interesting technological applications.Fil: Spada, Ramiro Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Macor, Lorena Paola. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hernández, Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ponzio, Rodrigo Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Ibarra, Luis Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Lorente, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Chesta, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Palacios, Rodrigo Emiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Iron oxide incorporated conjugated polymer nanoparticles for simultaneous use in magnetic resonance and fluorescent imaging of brain tumors

Conjugated polymer nanoparticles (CPNs) have emerged as advanced polymeric nanoplat-forms in biomedical applications by virtue of extraordinary properties including high fluorescence brightness, large absorption coefficients of one and two-photons, and excellent photostability and colloidal stability in water and physiological medium. In addition, low cytotoxicity, easy functional-ization, and the ability to modify CPN photochemical properties by the incorporation of dopants, convert them into excellent theranostic agents with multifunctionality for imaging and treatment. In this work, CPNs were designed and synthesized by incorporating a metal oxide magnetic core (Fe3 O4 and NiFe2 O4 nanoparticles, 5 nm) into their matrix during the nanoprecipitation method. This modification allowed the in vivo monitoring of nanoparticles in animal models using magnetic resonance imaging (MRI) and intravital fluorescence, techniques widely used for intracranial tumors evaluation. The modified CPNs were assessed in vivo in glioblastoma (GBM) bearing mice, both heterotopic and orthotopic developed models. Biodistribution studies were performed with MRI acquisitions and fluorescence images up to 24 h after the i.v. nanoparticles administration. The resulting IONP-doped CPNs were biocompatible in GBM tumor cells in vitro with an excellent cell incorporation depending on nanoparticle concentration exposure. IONP-doped CPNs were detected in tumor and excretory organs of the heterotopic GBM model after i.v. and i.t. injection. However, in the orthotopic GBM model, the size of the nanoparticles is probably hindering a higher effect on intratumorally T2-weighted images (T2 WI) signals and T2 values. The photodynamic therapy (PDT)—cytotoxicity of CPNs was not either affected by the IONPs incorporation into the nanoparticles.Fil: Arias Ramos, Nuria. Consejo Superior de Investigaciones Científicas; EspañaFil: Ibarra, Luis Exequiel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Biotecnología Ambiental y Salud - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Biotecnología Ambiental y Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Serrano Torres, María. Consejo Superior de Investigaciones Científicas; EspañaFil: Yagüe, Balbino. Consejo Superior de Investigaciones Científicas; EspañaFil: Caverzan, Matias Daniel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Palacios, Rodrigo Emiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: López Larrubia, Pilar. Consejo Superior de Investigaciones Científicas; Españ

Long-range photoinduced charge separation in tröger bases D/A dyads

Tröger´s base (and its derivatives) are compounds comprised of two aromatic (or polyaromatic) rings bridged by a diazocine aliphatic cycle. We report herein the photophysical properties of two series of novel Tröger´s bases (TB) asymmetrically substituted by electron donor (D) and electron acceptor (A) substituents. In TB series 3, a carbonitrile group (A[dbnd]CN) lies at the position 2 of the heterocycle, while position 8 is occupied by a series of D with increasing reductant capacity: H (3a), CH3 (3b), OCH3 (3c) or N(CH3)2 (3d). A novel TB series (5a-5d) which comprise the same D, but a 2,2-dicyanovinyl group (A = CHC(CN)2) as electron acceptor, was synthesized and fully characterized. TB absorption (νA max) and emission energies (νF max), fluorescence quantum yields (ΦF) and emission lifetimes (τF) were determined in a series of aprotic solvents covering a wide range of medium polarity (ε∼2-38). νF max, ΦF and τF largely depend on the polarity of the medium and the nature of D/A pair. From the solvatochromic study on νF max, it is concluded that upon excitation TB´s develop large degrees of charge separation (CT). Photophysically, 3a-3c resembles 4-(N,N-dimethylamino)benzonitrile derivatives showing internal CT state dipole moments (μ1 *) of ∼ 15–17 D. For 3d and the entire series 5, CT occurs throughout the diazocine ring giving rise to giant μ1 * (> 25 D). This is indeed an unusual result, because it strongly suggests that the aliphatic diazocine ring can couple the D/A redox centers as a π bridge would do.Fil: Dusso, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Lanza Castronuovo, Priscila Ailin. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnologia. Grupo de Investigacion En Quimica Analitica y Modelado Molecular.; ArgentinaFil: Montejano, Hernan Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Ramírez, Cristina L.. Universidad Nacional de Mar del Plata; ArgentinaFil: Parise, Alejandro Ruben. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Vera, Domingo Mariano Adolfo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnologia. Grupo de Investigacion En Quimica Analitica y Modelado Molecular.; ArgentinaFil: Moyano, Elizabeth Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

The quenching of indolic compounds by monosubstituted benzenes and the photoreaction with chlorobenzene

The quenching of the excited singlet of indole and its methyl derivatives by monosubstituted benzenes has been studied in three solvents of different polarities and bimolecular quenching rate constants have been determined. Below the diffusion limit the rate constants decrease when solvent polarity increases, with the exception of those for the quenching by benzonitrile. For the latter the rate constants are near the diffusion limit in all cases. The decrease may be understood in terms of a lower energy of the indole excited state in the more polar solvents. In cyclohexane the remnant emission in the presence of high concentration of the quencher is clearly red shifted, indicating the presence of a new emitting species that can be ascribed to the presence of an exciplex. In some cases the emission of the exciplex can be clearly separated from the molecular fluorescence. In the quenching by chlorobenzene in ethyl acetate and acetonitrile a new highly fluorescent product is formed. This photoreaction is observed with all the indole derivatives and the kinetics of the reaction was followed by the increase in fluorescence intensity at a wavelength were the reactants do not emit. Three major products were identified as phenyl substituted indoles by GC-MS and their fluorescence emission and excitation spectra.Fil: Rivarola, Claudia Rosana. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Previtali, Carlos Mario. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Metronomic Photodynamic Therapy with Conjugated Polymer Nanoparticles in Glioblastoma Tumor Microenvironment

Alternative therapies such as photodynamic therapy (PDT) that combine light, oxygen and photosensitizers (PSs) have been proposed for glioblastoma (GBM) management to overcome conventional treatment issues. An important disadvantage of PDT using a high light irradiance (fluence rate) (cPDT) is the abrupt oxygen consumption that leads to resistance to the treatment. PDT metronomic regimens (mPDT) involving administering light at a low irradiation intensity over a relatively long period of time could be an alternative to circumvent the limitations of conventional PDT protocols. The main objective of the present work was to compare the effectiveness of PDT with an advanced PS based on conjugated polymer nanoparticles (CPN) developed by our group in two irradiation modalities: cPDT and mPDT. The in vitro evaluation was carried out based on cell viability, the impact on the macrophage population of the tumor microenvironment in co-culture conditions and the modulation of HIF-1α as an indirect indicator of oxygen consumption. mPDT regimens with CPNs resulted in more effective cell death, a lower activation of molecular pathways of therapeutic resistance and macrophage polarization towards an antitumoral phenotype. Additionally, mPDT was tested in a GBM heterotopic mouse model, confirming its good performance with promising tumor growth inhibition and apoptotic cell death induction.Fil: Caverzan, Matias Daniel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Oliveda, Paula Martina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Beaugé, Lucía. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Palacios, Rodrigo Emiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Ibarra, Luis Exequiel. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Biotecnologia Ambiental y Salud. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Biotecnologia Ambiental y Salud.; Argentin

Hybrid mineral@silsesquioxane particles for water remediation: synthesis, characterization and application as adsorbent of As(V) and other water pollutants

Mineral-coated silsesquioxane particles of approximately 600 nm diameter were synthesized from the hydrolytic co-condensation of N-[3-trimethoxysilyl]-propyl]ethylenediamine (DAS) and tetraethyl orthosilicate (TEOS). The hybrid particles involve nanocomposites with a mineral core (montmorillonite—MMT—or goethite—Gt—nanoparticles) and coated with a silsesquioxane shell containing hydroxyl and amine groups. These particles were specially designed (exposing amino groups) to be highly efficient for the removal of As(V) and to enhance the adsorption properties of the minerals employed in this work. They were characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy, zeta potential, dynamic light scattering and thermogravimetric techniques such as dynamic scanning calorimetry and thermogravimetric analysis. The characteristics found in the composite particles compared with pure organosilane DAS/TEOS or with the unmodified minerals proved the effectiveness of the silanization process. As result, hybrid nanocomposite materials were obtained, denoting versatility in their adsorption properties of different types of pollutants. Moreover, all synthesized particles showed a high arsenic retention capacity; experimental results demonstrated that superficial modification of the minerals is the preponderant factor that determines their adsorbent properties, favoring the versatility of these materials making them suitable for the removal of pollutants of diverse charge and nature.Fil: Waiman, Carolina Vanesa. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Dell'Erba, Ignacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Gomez, María Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin

Visible light photopolymerization in BHDC reverse micelles: laser flash photolysis study of the photoinitiating mechanism

The photopolymerization of acrylamide (AA) in reverse micelles (RMs) of benzyl hexadecyl dimethylammonium chloride (BHDC) was investigated. The polymerization was performed by irradiation in the 500 nm region of the spectrum, employing as photoinitiating system the synthetic dye safranine-O and triethanolamine (TEOA) as co-initiator. The characterization of the nanoparticles of polyacrylamide was done by dynamic light scattering. Molecular weight determinations were carried out by viscosimetry. Small nanoparticles of polyacrylamide are formed with a low polydispersity and a molecular weight close to 106. The results were compared with those in AOT (sodium bis(2-ethylhexyl) sulfosuccinate) RMs. Laser flash photolysis was used to investigate the photoinitiating mechanism. The maximum of the T–T absorption spectra in RMs confirms that, in spite of its positive charge, the dyes remain at the interface co-micellizing with BHDC. The triplet lifetime is much longer in the RMs than in homogeneous organic solvents. The triplet quenching by TEOA was very much more effective in the RMs than in a homogeneous solvent. The quantum yield of formation of active radicals was evaluated from the transient absorption spectra. It was concluded that they are generated by an intermicellar electron transfer process followed by an intramicellar proton transfer reaction. The quantum yield was found to be 0.2 ± 0.02. A similar radical yield in a homogeneous solvent requires an amine concentration near 50 times higher.Fil: Porcal, Gabriela Valeria. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arbeloa, Ernesto Maximiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Previtali, Carlos Mario. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin