Antonio Muñoz

Fullerene sugar balls

Fullerene hexakis-adducts bearing 12 peripheral carbohydrate moieties have been prepared by grafting sugar derivatives onto the fullerene core through the copper mediated Huisgen 1,3-dipolar cycloaddition of azides and alkynes.

Glycofullerenes inhibit viral infection.

Water-soluble glycofullerenes based on a hexakis-adduct of [60]fullerene with an octahedral addition pattern are very attractive compounds providing a spherical presentation of carbohydrates. These tools have been recently described and they have been used to interact with lectins in a multivalent manner. Here, we present the use of these glycofullerenes, including new members with 36 mannoses, as compounds able to inhibit a DC-SIGN-dependent cell infection by pseudotyped viral particles. The results obtained in these experiments demonstrate for the first time that these glycoconjugates are adequate to inhibit efficiently an infection process, and therefore, they can be considered as very promising and interesting tools to interfere in biological events where lectins such as DC-SIGN are involved.

[60]Fullerene as Multivalent Scaffold: Efficient Molecular Recognition of Globular Glycofullerenes by Concanavalin A

Financial support by the MICINN of Spain (CTQ2008-00795/BQU, CTQ2008-01694), the CAM (MADRISOLAR-2 S2009/PPQ-1533), Consolider- Ingenio (CSD2007-00010, Nanociencia Molecular), and the EU (FUNMOL FP7-212942-1) is greatly appreciated. A.M. thanks the MICINN for an FPI Studentship

A New exTTF-Crown Ether Platform To Associate Fullerenes: Cooperative n−π and π−π Effects

A new and readily available exTTF-bis(crown ether), 1, efficiently recognizes C60 as well as C70 by means of cooperative π-π and n-π interactions. The geometrical (concave-convex) and electronic (donor-acceptor) complementarity accounts on one hand for remarkable binding strengths, with association constants reaching 10(7) M(-1) in benzonitrile, and on the other hand for lifetimes of the photogenerated radical ion pair state on the order of 45 ps.

Modelling low energy electron and positron tracks for biomedical applications

Abstract Purpose: To incorporate the effects of low energy electrons and positrons into radiation interaction models. Materials and methods: The simulation method proposed here was based on experimental and theoretical cross section data and energy loss spectra we have previously derived. After a summary of the main techniques used to obtain reliable input data, the basis of a Low Energy Particle Track Simulation (LEPTS) procedure was established. The programme is specifically designed to describe electron and positron interactions below 10 keV, down to thermal energies. Results: Single electron and positron tracks in water are presented and the possibility of using these results to develop tools for nanodosimetry is discussed. Conclusions: Standard approximations based on high incident energies, such as the Born-Bethe theory, are not suitable to simulate electron and positron tracks below 10 keV. Prior to the inclusion of low-energy effects in a radiation model, an appropriate study is required to determine both the interaction cross sections and the energy loss spectra.

Nanorods versus nanovesicles from amphiphilic dendrofullerenes.

Three new amphiphilic dendrofullerenes endowed with 4, 8, and 16 carboxylic groups have been efficiently prepared by using a click chemistry methodology. These amphiphilic fullerene derivatives aggregate forming micelles, nanorods, or hollow vesicles depending on the concentration and on the solid substrate.

Modelling single positron tracks in Ar

In this study, we present a complete set of positron interaction cross sections for scattering from Ar, for incident energies ranging from 0 to 10 keV. Experimental data have been critically reviewed from previous experiments performed at the Australian National University and University College London. Differential and integral cross sections, including the effect of positronium formation, have been calculated by using two different optical potential methods. The results of these calculations, in combination with experimental cross sections and experimental energy-loss spectra, have been established as input parameters for an event-by-event Monte Carlo simulation procedure to generate single positron tracks in argon. The reliability of this method to obtain energy deposition models at the nano-scale is also discussed.

Current prospects on Low Energy Particle Track Simulation for biomedical applications

The Low Energy Particle Track Simulation code is a radiation interaction simulation tool specifically designed to describe electron and positron interactions below 10 keV at a molecular level. Relying on carefully selected, preferentially experimental input parameters that account for all expected scattering processes, it provides detailed results about all collisional events undergone by an incident radiation particle during its slowdown until thermalisation. Here, we give an up-to-date description of its input data sources and selection procedure and summarise the current contents of the resulting database.

Energy Deposition Models at the Molecular Level in Biological Systems

Abstract In this study we have developed a model to describe the electron interaction of intermediate and high energy electrons (10–10000 eV) with some molecules of biological interest. Differential and integral electron scattering cross sections have been calculated with an optical potential method following an independent atom representation. Important improvement related to relativistic corrections, many-body effects, local velocity considerations and a screening correction procedure which take into account the overlapping of the constituent atoms in the molecule have been introduced to improve the accuracy and applicability of the method for a high variety of molecular targets. The accuracy of these calculations has been checked by comparison with total electron scattering cross section data we have measured in a transmission beam experiment with experimental errors within 5%. Finally, we have developed a Monte Carlo simulation program, based on the general tools of GEANT4, which uses as input parameters our calculated cross sectional data and the energy loss distribution functions based on the experimental energy loss spectra. This simulation procedure allows energy deposition models at the molecular level that could be very useful in biological and medical applications when microscopic energy deposition patterns are required.

Monte Carlo Methods to Model Radiation Interactions and Induced Damage

This review is devoted to the analysis of some Monte Carlo (MC) simulation programmes which have been developed to describe radiation interaction with biologically relevant materials. Current versions of the MC codes Geant4 (GEometry ANd Tracking 4), PENELOPE (PENetration and Energy Loss of Positrons and Electrons), EPOTRAN (Electron and POsitron TRANsport), and LEPTS (Low-Energy Particle Track Simulation) are described. Mean features of each model, as the type of radiation to consider, the energy range covered by primary and secondary particles, the type of interactions included in the simulation and the considered target geometries are discussed. Special emphasis lies on recent developments that, together with (still emerging) new databases that include adequate data for biologically relevant materials, bring us continuously closer to a realistic, physically meaningful description of radiation damage in biological tissues.