Ricardo Mallavia

Conjugated polymer microspheres for "turn-off"/"turn-on" fluorescence optosensing of inorganic ions in aqueous media.

The synthesis and characterization of a novel water-compatible microsized material, based on fluorescent conjugated polymers (CPs), and its applicability for optical sensing of inorganic ions of environment interest (copper and cyanide) in water media is here described. Polyfluorene-based fluorescent CPs were synthesized and functionalized with imidazole moieties (selective recognition element) and a terminal double bond (covalently linked to an organic matrix) through a postfunctionalization strategy. Further, microspheres of the novel imidazole-functionalized fluorescent CPs, able to work in water media, were synthesized via a microemulsion and polymerization procedure. The synthesized imidazole-functionalized CP microspheres were then evaluated as fluorescence turn-Off sensing materials for Cu(2+) detection in aqueous media. Analyte detection was based on the quenching effect of the Cu(2+), selectively recognized by the imidazole group, on the polymer fluorescence emission. The developed optosensor exhibits a detection limit of 1 μg/L for the determination of Cu(2+) in water with a reproducibility of 4%. The synthesized microsized material was also evaluated for the turn-on optosensing of cyanide in water, measuring the recovery of the emission signal from the CP that has been previously deactivated by the presence of quencher species. The turn-On optosensor allows the selective determination of free cyanide in aqueous solution with high sensitivity (detection limit of 18 μg/L), obtaining a reproducibility of 2.9%. A high sample throughput (between 7 and 12 samples per hour) was achieved in both cases. Analytical applicability of the fluorescent CP microsphere materials has been successfully demonstrated by tap and mineral water analysis.

A Novel Antioxidant Phenyl Disaccharide from Populus tremula Knotwood

The complete characterization of two compounds obtained from the acetone extract of Populus tremula knotwood has been was achieved using LC-DAD-MS, MS/MS, IR and NMR. The new compounds were unequivocally identified as a mixture of the ester isomers of the (E) and (Z) p-coumarate of 1-O-rutinose. The isomers showed the capacity to inhibit lipid peroxidation induced by tert-butylhydroperoxide and to trap peroxyl radicals, as determined by a chemiluminescence method. These new phenyl disaccharides also showed a significant ORAC (oxygen radical absorbance capacity) value, i.e. 11.7 microM TE (Trolox Equivalents).

Poly(methyl vinyl ether- alt -maleic acid) and ethyl monoester as building polymers for drug-loadable electrospun nanofibers

New biomaterials are sought for the development of bioengineered nanostructures. In the present study, electrospun nanofibers have been synthesized by using poly(methyl vinyl ether-alt-maleic acid) and poly(methyl vinyl ether-alt-maleic ethyl monoester) (PMVEMA-Ac and PMVEMA-ES, respectively) as building polymers for the first time. To further functionalize these materials, nanofibers of PMVEMA-Ac and PMVEMA-ES containing a conjugated polyelectrolyte (HTMA-PFP, blue emitter, and HTMA-PFNT, red emitter) were achieved with both forms maintaining a high solid state fluorescence yield without altered morphology. Also, 5-aminolevulinic acid (5-ALA) was incorporated within these nanofibers, where it remained chemically stable. In all cases, nanofiber diameters were less than 150u2009nm as determined by scanning and transmission electron microscopy, and encapsulation efficiency of 5-ALA was 97u2009±u20091% as measured by high-performance liquid chromatography. Both polymeric matrices showed rapid release kinetics in vertical cells (Franz cells) and followed Higuchi kinetics. In addition, no toxicity of nanofibers, in the absence of light, was found in HaCaT and SW480 cell lines. Finally, it was shown that loaded 5-ALA was functional, as it was internalized by cells in nanofiber-treated cultures and served as a substrate for the generation of protoporphyrin IX, suggesting these pharmaceutical vehicles are suitable for photodynamic therapy applications.

P-172: Determination of Hole Mobilities in New Blue Emitting Organic Diodes by Means of Impedance Spectroscopy

In this work we have fabricated passive diode matrices based on a new blue emitting organic electroluminescent polymer. In order to determine the capacitive response at typical display operating frequencies, impedance vs frequency measurements have been carried out at different bias. In addition, hole mobilities have been extracted by fitting a new theoretical model to the measured admittance, that takes into account the effect of an injection barrier, obtaining values from 10−12 m2/Vs to 10−10 m2/Vs with increasing bias.