title: Surpassingly competitive electromagnetic field enhancement at the silica/silver interface for selective intracellular surface enhanced Raman scattering detection.
abstract: A thin plasmonic nanofilm is formed by preformed silver nanoparticles (30 nm) in the matrix of poly(vinyl alcohol) adsorbed on silica microparticles (1.5 μm) (SiO2@Ag-PVA). By applying finite element method (FEM) analysis the surface enhanced Raman spectroscopy (SERS) enhancement factors (EFs) can reach 10(5) with higher values from 10(9) to 10(11) in the silver layer of 5 nm thickness. Nanoparticles in the SiO2@Ag-PVA nanofilm need at least 15 nm radius to exhibit SERS EFs greater than 10(7). High values of this enhancement at the silver/silica interface of spherical geometry can be reached faster by using a 532 nm compared to 785 nm excitation wavelength. By this approach different SERS spectral features can be distinguished between live fibroblasts with spread ("healthy" state) or round ("unhealthy" state) shapes. Characteristic features of secondary protein structures, detection of different acidic conditions and cholesterol with at least a 3-fold higher sensitivity are examined. Moreover, a greater amount of glucose (glucogen) and also tyrosine can be monitored in real time. This is important in identification of higher risk of diabetes as well as in several genetic metabolic disorders (e.g., phenylketonuria, tyrosinaemia type II and tyrosinosis).
authors.affiliation: Max-Planck Institute of Colloids and Interfaces, Department of Interfaces, D14476 Potsdam, Germany.
authors.forename: Darya
authors.initials: D
authors.lastname: Radziuk
authors.affiliation: Max-Planck Institute of Colloids and Interfaces, Department of Interfaces, D14476 Potsdam, Germany.
authors.forename: Helmuth
authors.initials: H
authors.lastname: Möhwald
mesh_terms: D000327:Adsorption; D000818:Animals; D004574:Electromagnetic Fields; D042541:Intracellular Space / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry; D051379:Mice; D008863:Microspheres; D041681:NIH 3T3 Cells; D011142:Polyvinyl Alcohol / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D012834:Silver; D012822:Silicon Dioxide; D011142:Polyvinyl Alcohol
keywords: cell; intracellular; silica; silver; surface enhanced Raman scattering