ANNUAL REPORT 2011 - Instituto de Estructura de la Materia

Finally, we have also conducted a work is in collaboration with the group of Ablation Plasma Spectroscopy to obtainsynthetic glass (fulgurites) in building materials silicon base by applying continuous and pulsed lasers andsubsequent identification by laser ablation techniques (LIBS) and Raman. Preliminary results show that irradiatingwith continuous CO 2 lasers fulgurite-like materials are generated bearing a composition similar to those found innature.INFRARED AND RAMAN BIOSPECTROSCOPYWe have continued this research line by measuring infrared and Raman spectra of blood fractions from sixtysubjects, forty three of them affected by Alzheimer’s disease and the rest being healthy controls. Following themathematical treatment of spectra for normalization and baseline corrections, multivariate analysis was performed,particularly ROC curves, discriminant analysis and multilayer neural networks for classification of samples.Classifications of the mononuclear leukocyte fractions were obtained with approximately 85% sensitivity andspecificity, generated by infrared amide I bands of protein -structure. Similar classification results were obtainedthrough the infrared spectra of the plasma fraction by considering the amide I region and the 1150-1000 cm -1 rangecontaining CO bands of alcohols and peroxides generated by oxidative stress characteristic of this disease. On theother hand, multivariate analysis of the 800-350 cm -1 Raman region of this fraction allows classification of bloodplasma samples with about 90% sensitivity and specificity, due to spectral differences caused by tertiary structure ofprotein side chains containing tryptophan.STRUCTURE OF BIOLOGICAL SYSTEMS IN FOODIn collaborationwith the Instituteof Scienceand Technology of Food andNutrition (ICTAN, CSIC) we haveconducted a studyrelated to applications ofFTIRspectroscopyaimed at determining the structuresof lipidsandproteins and theirpossible interactionsin the formation ofvariousoil-in-water emulsions. Particularly, emulsionsstabilized with soy protein and other emulsions stabilized with soy protein, sodium caseinate and transglutaminasehave been studied. A relationship between thetextural and proteolipid structuralpropertieshave been found to bedependent on the proteinstabilizersystem used in these emulsions.SURFACE INTEGRAL SCATTERING FORMULATION IN 3DA formulation of this kind has been developed on the basis of the Sttratton-Chu equations, for a system of severalscatterers with arbitrary shapes and dielectric response. The code is now running for scatterers with arbitrary shapes,thanks to the implementation of flexible surfaces (now using in particular 3D Gieli’s superformula). Tests havesatisfactorily reproduced the well known: Mie scattering patterns for a single sphere; extended-Mie theory for spheredimers; other results (FDTD, DDA) for complex shapes (nanocubes).SERS ON NANOSTARSWe have investigated theoretically the optical properties associated to Localized Surface Plasmons of Agnanoparticles known as 3D nanostars without axial symmetry (modelled by a supershape). Large field intensityenhancements are obtained at the tips, which make these nanostars specially suitable as (single-nanoparticle) SERSsubstrates, by hosting molecules for SERS sensing applications. Indeed, we have very recently extended such studyto revealing strong LSP in the visible and NIR, and confirming their performance as suitable (single-nanoparticle)SERS substrates. In additionby exploiting genetic optimization algorithms, we have shown that such shapes lead,among a variety of them, to maximized LSP cross sectionsSURFACE PLASMONS ON EFFECTIVEΜ0) METAMATERIALSWe have investigated the optical properties of media with negative magnetic response (μ