Bio-inspired coated silver nano-particles for the design of effective and safe biocides.
Research field: - Computational chemistry - Life sciences & biotechnology
Duration of stay: 1 year starting end 2016
Condition: the grant will be allowed depending on the quality of the project and of the applicant to the CEA Euro-Talent program
Man and environment are highly exposed to silver release from the use of Ag nanoparticles (AgNP). The design of AgNP biocides "safer - by-design " is an important goal. Our recent work on the complexation of the Ag+ ion by sulphur molecules (bioinspired proteins and ligands containing 1,2 or 3 sulphurs (1)), leads us to propose the construction of AgNP clusters bridged by bioinspired sulphur ligands. These assemblies, too big to be assimilated (by the body and eukaryotic cells ( endocytosis )), will retain a biocidal effect through controlled release of Ag+ in the medium capable of penetrating bacteria and destroy them.
Synthesis of AgNP coated with sulphur ligands and analysis of their structure by XAS (Local engineer in chemistry) According to (1) a two-sulphur peptide can promote the dissolution of AgNP while a pseudo peptide containing 3 sulphurs induces the formation of controlled size assemblies. These analyses will be detailed in the project where the ligands will be synthesized locally. In particular, the XAS sulphur K-edge spectroscopy will measure the average length of Ag-S bonds at the surface of the NP. XPS experiments, to characterize the bonds between the ligands and AgNP will also be realized.
Study of the surface reactivity of AgNP by theoretical approaches (Eurotalent PostDoctoral fellow to be hired)
The adsorption energies of our sulphur-containing molecules (1, 2 and 3 S) on various crystal planes of Ag will be calculated with the software VASP (plane waves, "infinite" surface) to evaluate their greater or lesser adhesion to NPs. The minimum energy required to extract an Ag atom will be calculated to evaluate the solubilization of the surface Ag atoms by these ligands. These complex calculations will be made on defects or edges of the crystal planes present on the NP with the VASP and/or BigDFT programs. Finally atomic (or coarse grained) models parameterized from the quantum calculations and XAS and XPS measurements, will be proposed for the formation of nanoparticles assemblies. The mutual interaction between several nanoparticles and their reticulation by our bridging molecules will be modelled in water solvent with the Molecular Dynamics program GROMACS.
Bioassays (Local biologist)
The influence of the coating of AgNP on their biocidal and cytotoxic effect will be tested, respectively, on E. coli and hepatocyte cell line HepG2.
(1) Veronesi et al Inorg. Chem., 2015, 54, 11688−11696)
The Candidate :
The project is multi-discplinary involving chemists, physicists and biologists. The candidate will be in charge of the theoretical part of the project. He (she) will run state of the art calculations using mainly theoretical chemistry programs on UNIX/Linux workstation clusters and super-computers.
The candidate should have excellent knowledge in computational chemistry – Previous use of VASP and / or BigDFT will be a key asset.
The Candidate can be of any nationality;
Applicants shall not have resided or carried out their main activity (work, studies, etc.) in
France for more than 12 months in the 3 years immediately prior the submission of their complete proposal.
be in possession of a Doctoral degree
have at least 4 complete years of experience in research (or a full-time equivalent) after obtaining the college degree that formally gives you access to PhD studies in the country in which you graduated or in the host country.
The candidate will receive a so called “Incoming CEA Fellowships (ICFs)” of around 2200-2500 euros/month (tax free) depending on experience - http://eurotalents.cea.fr
Serge Crouzy PhD HDR
Groupe de Modélisation et Chimie Théorique
Laboratoire de Chimie et Biologie des Métaux
Institut de Biosciences et Biotechnologies de Grenoble
CEA Grenoble UMR CEA/CNRS/UJF 5249
17, rue des martyrs
38054 Grenoble Cedex 9
Bat. K pièce 110