ANNUAL REPORT 2011 - Instituto de Estructura de la Materia

NANOSENSORS BASED ON SERS FOR DETECTION OF DRUGS USED IN SPORT DOPINGWe have made significant progress in the research involving the application of SERS technique for detection andcharacterization of drugs used in sport doping (DSD). This research was the basis of the PhD work of IreneIzquierdo. During 2011 significant results have been published regarding the SERS study of β-agonists clenbuterol,salbutamol and terbutaline, and aminoglutethimide, an aromatase inhibitor used in athletes to avoid muscle loss. Theuse of Ag NPs shaped triangular prisms lead to much lower detection limits of these compounds to levels notdetected by conventional techniques up to now. In this regard, a comparative study of the efficacy of NPs withdifferent nature and morphology was performed. Also, since the SERS detection of DSDs can be done univocally bySERS spectra, which represents actual fingerprints of these compounds, a multicomponent analysis or mixtures ofthese doping agents is also possible. Furthermore, this study was also carried out together with a theoretical study ofthe vibrational modes of the doping agents. In addition, from the adsorption isotherms of the investigated drugs onmetal NPs, it was possible to obtain important structural parameters of these molecules, such as the adsorptionconstant on the nanostructures employed, the detection limit, the SERS enhancement factor and the maximum SERSsignal. Likewise, it was successfully finished the SERS study of some doping drugs of difficult study, such asnandrolone, thanks to the synthesis of a cyclodextrin with enhanced affinity towards the surface of Ag byderivatization with DTC. The spectra analysis has allowed important structural information about the mechanisms ofinteraction between the DSD and host linked on the surface. This research finally gave rise to a patent that iscurrently under consideration by the Technology Transfer Office of CSIC.LASER TECHNIQUES APPLIED TO THE STUDY AND CONSERVATION AND RESTORATION OFWORKS OF ART AND MONUMENTSWithin this line of research it was completed the work involving the application of SERS and SEF spectroscopy tothe study of synthetic high performance organic pigments carried out by the PhD student Elena del Puerto. Thepigments studied in this work were several quinacridone derivatives, known for their durability, partly due to itshigh insolubility in aqueous media, what makes very difficult to address their characterization by spectroscopictechniques. To accomplish this, we have firstly determined the optimal conditions for carrying out the dispersion ofthese molecules. This was done by using as dispersant agents functionalized calixarenes with different sizes (from 4to 8 benzene rings), finding a good correlation between the cavity of the host molecule and the size of the pigment.The adsorption of these molecules on metals by Langmuir-Blodgett films also allowed their characterization, as wellas their study by SERS and SEF as a function of the distance of the pigment with respect to the surface. During thisyear we have completed the study of two new derivative quinacridone pigments with a great interest in thedevelopment of OLED (Organic Light Emission Diodes), which began to be characterized the previous year. Thesederivatives were dichloroquinacridone and dimethylquinacridone, whose characterization has been carried out by thespectra corresponding SERS and SEF. In some cases it was necessary the use of other dispersing agents such asalkylic and imidazolic ionic liquids, as well as ,-alkyldiamines, to obtain acceptable SERS spectra.Raman spectroscopy and SERS techniques have also been applied in the study of pigments contained in ancientMoroccan Islamic manuscripts. In this regard, the application of the SERS technique has been useful in identifyingthe red and yellow pigments of organic nature, which can not be characterized by conventional techniques due to thehigh emission of fluorescence of these dyes. SERS spectra obtained from pink red inks of the latter colors revealedthe presence of carmine red, which are also present in black inks with reddish hues. This work was made possible bya bilateral collaboration with researchers CNRST CSIC-University Moulay Ismail of Meknes in Morocco.The SERS technique has been used in the characterization of dark-colored residual substances found in the cave ofLascaux (France). These substances are produced by the combined action of microorganisms on the paint that are inthe walls of this cavern. The SERS technique has allowed the identification of these compounds, due to attenuationof the fluorescence, leading to the structure of these materials, so that the origins of such degradation can beunderstood. This project was conducted in collaboration with Prof. C. Saiz-Jimenez of IRNAS (CSIC).During the latter year we continued with the application of Raman spectroscopy in the characterization of molecularorganic additives traditional and commercial. While traditional additives (egg, sugar, etc.) have a known structure,the structures of the commercial additives are very complex, being a mixture of several compounds and thereforedifficult to interpret. The modification of the hydration process of traditional binders with different additives hasbeen studied by Raman spectroscopy, analyzing the different polymorphic forms of CaCO 3 resulting from thepresence of the additive. With respect to commercial additives we are still working on obtaining the SERS spectra ofthese for their identification in hardened materials. The recovery of waste water treatment plants and paper industryas a feedstock for the production of new materials is done in collaboration with the Department of Synthesis,Characterization and Materials Recycling IETcc. In the case of using paper pulp, new types of hydrotalcitescrystalline phases have been identified by Raman spectroscopy.63