RESEARCH TEAM GRANTS IN SCIENCE AND TECHNOLOGY 2006 FINAL REPORT I. PROJECT PRESENTATION PROJECT TITLE CODE Computer Simulation Laboratory of Nanomaterials and Biological Systems of Experimental Interest ADI-24 PROJECT DIRECTOR SIGNATURE Gonzalo Gutiérrez Gallardo CONTACT INFORMATION Las Palmeras 3425, Ñuñoa; Región Metropolitana - MAIN INSTITUTION Universidad de Chile PERIOD INFORMED April-07 - April 2011 2 a) Main researchers’ information MAIN RESEARCHER (Complete Name) SIGNATURE Eduardo Menendez-Proupin WORKING ADDRESS PHONES EMAIL Dept. Física, Fac. Ciencias, U. [email protected] de Chile MAIN RESEARCHER (Complete Name) SIGNATURE Fernando Danilo Gonzalez-Nilo WORKING ADDRESS PHONES EMAIL Center for Bioinformatics and Molecular Simulations (CBSM) danilo.gonzaleznilo@gm Universidad de Talca ail.com 2 Norte 685, Casilla 721, Talca - Chile 3 b) Associated researchers’ information ASSOCIATED RESEARCHER (Complete Name) SIGNATURE Walter Orellana WORKING ADDRESS PHONES EMAIL Dept. Fisica, UNAB [email protected] ASSOCIATED RESEARCHER (Complete Name) SIGNATURE David Laroze WORKING ADDRESS PHONES EMAIL Instituto de Alta Inv., U. [email protected] Tarapaca ASSOCIATED RESEARCHER (Complete Name) SIGNATURE Jaime Henriquez WORKING ADDRESS PHONES EMAIL Center for Bioinformatics and Molecular Simulations (CBSM) Universidad de Talca 2 Norte 685, Casilla 721, Talca - Chile 4 II. EXECUTIVE SUMMARY The Project Anillo ACT-24 is entitled Computer simulation laboratory of Nanomateriales and biological systems of experimental interest, and its main research goal was a) the study of struc- tural, dynamic, mechanic, electronic, magnetic and optical properties of nanomaterials and b) the study of biological systems such as transmembrane proteins (TRP channels) and the catalytic reaction mechanism in enzymes (PEPCK). During the course of the pro- ject, new topics arose, such as the interface between an organic material and a metal, shock waves and hypervelocity impacts. These studies were performed by means of computer simulation at the molecular level, which has shown to be a very useful technique in the theoretical study of systems with time and length scale going from the atomic to nanoscopic and, eventually, to microscopic size, such as the systems studied in this proposal. In addition, we explored methodological and technical topics, such as the development of a molecular dynamics code, the installation of a high performance computing system (304 cores) and a database web platform for nanoparticles. The results of these investigations present an interest not only from a basic point of view, but also they are capable of being applied to strategic researchs interest for the development of our country, in areas such as nanotechnology and biotechnology. The Anillo ACT-24 rested on two fundamental pillars: the Group of NanoMaterials, www.gnm.cl, of the Departamento de F´ısica, Facultad de Ciencias of the Universidad de Chile (GNM), and the Center of Bioinformatic and Molecular Simulation,http://cbsm.utalca.cl/, of the Universidad de Talca (CBSM). The synergy generated by this union allowed us to expand the research issues ini- tially pointed out, as well as venture in more applied areas and interactions with the public sector that, in other way, would have been impossible to do. The Anillo begun with a nucleus of three titular researchers, three reasearch associates and a group of collaborators both from Chile and abroad, as well as 10 graduate and undergraduate students. These researchers and students came from Antofagasta, La Serena, Santiago, Talca, Valdivia and Puerto Montt, with collaborators in Brazil, France and Spain, USA, India, Italy, Japan and Sweden. Through the three years of resear- ch, our collaborators net grew up, and 4 postdoctoral researchers, 25 graduate and undergraduate students, as well as foreign researchers joined the team. During the course of the project, we worked driving three main areas: scientific research, human resources training and outreach of the research results, to both specialized audience and public at large. The main results obtained by our research are embodied in the 56 (ISI) published papers, as well as more than 100 congress and conference presentations, in addition to other articles published in journals of continental and national circulation. In the issue nano structured materials and bulk properties, we studied the properties of the aluminium oxide in amorphous state and its crystalline phase γ-Al2O3, developing a structural model that presents a good agreement with experiments, which let us quantify the ionic character of the bond, as well as elucidate the change in its vibrational properties as the sample is put under pressure. In the same line, we studied the compound CdTeOx, a material of current importance in the search for greater efficiency in photovoltaic cells: using ab- initio molecular dynamics calculations on this compound in amorphous state, we could correlate the structure to the emission spectra of photoelectrons (XPS) obtained experimentally. Another amorphous material investigated was the CuZr, alloy that forms a metallic glass, which has many applications as structural material due to its excellent mechanical properties. Here we studied, by means of computer simulation, its structure and vibrational states in liquid and amorphous state, determining that the fundamental building block is a distorted icosahedron. The study of the mechanic and elastic properties of materials is an issue that can be addressed with high precision by means of calculations based on quantum mechanics. In this way, we performed a theoretical- experimental work focused on platinum, that allowed us to determine its elastic constants in a wide range of pressures, getting an excellent agreement with the experiments in those ranges where the data is available. Using the same calculation technique, we studied the mechanical properties of the hydroxiapatite and fluorapatite, key components of the enamel and body of the teeth. In particular, the fluorapatite is found in sick teeth, degrading its mechanical strength. Properties of surfaces and interfaces was another research topic, for both semiconductor and metallic systems. Here we performed basic studies, as well as applications to specific material physics problems and biological systems, working the researchers from GNM (U. de Chile) and the CBSM (U. Talca) in close contact. Thus, joining efforts and experiences, we could address pro- blems from a theoretical-experimental point of view, in organic and inorganic systems. Below we highlight the main achievements. In collaboration with researchers from Universidad de Sevilla, we studied the adsorption of gold atoms in anatase nitrogen surfaces, a titanium oxide variant with photocatalytic properties of great current interest in the search for stable and cheap catalyzers that can be activated by light. Another study of surface properties was carried out together with an experimental group from U. de Chile: we studied the influence of edges in the electric conductivity of thin gold films. Also, we determined the potential energy barrier between grain boundaries using quantum mechanics calculations and images of the TEM microscope. In the area of interfaces be- tween organic and metallic systems, we highlight the study about adsorption of the oligopeptide RGD in titanium dioxide. This topic has direct relationship with the response of tissues to tita- nium implants, vastly used nowadays in medicine, since the titanium oxide is the natural interface between tissues and titanium (see figure). In the field of biology is possible also to identify certain immunological responses through the interactions between atomic gold structures and proteins such as opsonin, fibronectin and others. We modeled such a system with gold clusters interacting with thiols, obtaining that the interaction of the organic compound was energetically more stable in the deprotonated state than in the protoned state. Finally, another study performed is realted to the corrosion of metallic oxides by organic acids, a problem of practical importance both in industry as in laboratory. In particular, we studied copper and zinc oxides attacked by formic acid, finding through quantum mechanics calculations that copper has a much higher resistence, due to the interaction that, unlike zinc, covers an hydroxylated layer and a molecule of water. (a) Aspartate molecule on TiO2 surface. (b) AGS-FA-PAMAM-QDot in tu- moral cell Figura 1: Example of metal-organic interfaces and QD-dendrimers. The sutdy of quantum dots was an issue raised from the beginning, but was soon extended to its interaction with organic systems. This issue was addressed in different levels of complexity and approximations. One of the studies undertaken is related to the behavior of a quantum dot under a non-constant magnetic field, using the approximation of effective mass. In the same way, we studied the magneto-optic properties of the semiconductor CdxZn1−xSe, showing that the thermal annealing produces evaporation of Cd, modifies the form of quantum confinement and allows to tune in its magnetic properties. The theoretical-experimental study undertaken jointly with the Institute of Chemistry of the U. de Talca, in relation with the synthesis and characterization of the complex dendrimer-quantum dot, is particularly interesting and of great importance due to its application to obtaining images of tumor cells. In fact, such is the progress in this investigation that a first test has become possible