title: Theoretical study of structural and optical properties of noble metal cluster-dipeptide hybrids at defect centers of MgO.
abstract: We present the theoretical investigation of structural and optical properties of silver and gold cluster-dipeptide hybrids bound to the F(S) defect of the MgO (100) surface. We use DFT and its TDDFT variant combined with the polarizable embedded cluster model for the description of the extended MgO environment. As model peptide we have chosen CysTrp since the cysteine residue interacts strongly with metal particles through the sulfur atom and tryptophan is the most important chromophoric amino acid. Our results show that in the case of CysTrp bound to the supported Ag(4) cluster an intense optical signal arises at 400 nm. In contrast, in the case of gold no strongly localized absorption is present since the optical response of supported gold-peptide hybrids is dominated by a large number of low intensity d-electron excitations spread over a broad energy range. Such a localized optical signal which is present in supported silver hybrids can be exploited for the optical detection of peptides and thus can serve as basis for the development of biosensing materials.
authors.affiliation: Department of Physics, Free University Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kulesza
authors.forename: Roland
authors.initials: R
authors.lastname: Mitrić
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bonačić-Koutecký
mesh_terms: D004151:Dipeptides / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D011789:Quantum Theory; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D004151:Dipeptides; D008277:Magnesium Oxide; D012834:Silver; D006046:Gold