1.- NANOMAGMA Focused Report More info

2.- E-Nano Newsletter Issue 23 More info

3.- E-Nano Newsletter Issue 15 More info

4.- Nanomagma Flyer More info

WP2 - Material design and modeling of devices

1.- Magneto-optical control of Forster energy transfer Physical Review B 83, 165426 (2011)

2.- Fluorescence quenching by a metal nanoparticle in the extreme near-field regime Optics Letters, Vol. 35, Issue 3, pp. 291-293 (2010)

3.- Radiative corrections to the polarizability tensor of an electrically small anisotropic dielectric particle Opt Express. 2010 Feb 15;18(4):3556-67

4.- Fluorescence signal of a single emitter coupled to a nanoparticle through a plasmonic film J. Opt. A: Pure Appl. Opt. 11 (2009) 11400

WP3 - Materials development and nanostructuration

1.- Magneto-optic enhancement and magnetic properties in Fe antidot films with hexagonal symmetry Physical Review B 81, 054424 (2010)

2.- Active magneto-plasmonics in hybrid metal–ferromagnet structures Nature Photonics | VOL 4 | FEBRUARY 2010

3.- Magneto-optical effects in interacting localized and propagating surface plasmon modes Optics Express 15635 Vol. 18, No. 15 (2010)

4.- Intertwined magneto-optical and plasmonic effects in Ag/Co/Ag layered structures Physical Review B 80, 125132 (2009)

5.- Magnetoplasmonic nanostructures: systems supporting both plasmonic and magnetic properties J. Opt. A: Pure Appl. Opt. 11 (2009) 114023

6.- Plasmon-enhanced magneto-optical activity in ferromagnetic membranes Applied Physics Letters 94, 263101 (2009)

WP4 - Materials/structures characterisation

1.- Photocoercivity of nano-stabilized Au: Fe superparamagnetic nanoparticles. Adv Mater. 2010 Sep 22;22(36):4054-8

2.- 3D near-field optical characterization of gold/silica nanocomposite thin film. More info

3.- Plasmon induced modification of thetransverse magneto-optical response in Fe antidot arrays. Phys. Status Solidi RRL 4, 271–273 (2010)

4.- Plasmon-Induced Magneto-Optical Activity in Nanosized Gold Disks. PRL 104, 147401 (2010)

5.- Coupling between magnetic and optical properties of stable Au–Fe solid solution nanoparticles. Nanotechnology 21 (2010) 165701

6.- Exchange bias in laterally oxidized Au/Co/Au nanopillars Applied Physics Letters 94, 062502 (2009)

WP5 - Sensor and biosensor

1.- Surface plasmon resonances of clustered nanoparticles Plasmonics (2011) 6:407--412

2.- Enhancement of the magnetic modulation of surface plasmon polaritons in Au/Co/Au films Applied Physics Letters 97, 183114 (2010)

3.- Colloidal Au-enhanced surface plasmon resonance imaging: application in a DNA hybridization process Applied Physics Letters 97, 183114 (2010)

4.- Femtosecond surface plasmon interferometry Optics Express 8424 Vol. 17, No. 10 (2009)

5.- Assessment of the Multiphase Interaction between a Membrane Disrupting Peptide and a Lipid Membrane J. Phys. Chem. B, 2009, 113 (43), pp 14369–14380

6.- Sensing based on assessment of non-monotonous effect determined by target analyte: Case study on pore-forming compounds Biosensors and Bioelectronics 24 (2009) 3517–3523

 Magneto-optical control of Forster energy transfer

Physical Review B 83, 165426 (2011)

Authors
R. Vincent * and R. Carminati
Institut Langevin, ESPCI ParisTech, CNRS, 10 rue Vauquelin, F-75231 Paris Cedex 05, France


Abstract
We introduce a general framework to study dipole-dipole energy transfer between an emitter and an absorber in a nanostructured environment. The theory allows us to address Forster resonant energy transfer (FRET) between a donor and an acceptor in the presence of a nanoparticle with an anisotropic electromagnetic response. In the particular case of a magneto-optical anisotropy, we compute the generalized FRET rate and discuss the orders of magnitude. The distance dependence, the FRET efficiency, and the sensitivity to the orientation of the transition dipoles orientation differ from standard FRET and can be controlled using the static magnetic field as an external parameter.

  Fluorescence quenching by a metal nanoparticle in the extreme near-field regime

Optics Letters, Vol. 35, Issue 3, pp. 291-293 (2010) 

Authors
E. Castanié, M. Boffety, R. Carminati
Institut Langevin, ESPCI ParisTech, CNRS UMR 7587, 10 rue Vauquelin, 75231 Paris CEDEX 05, France

Abstract
We study the spontaneous decay rate of a dipole emitter close to a metallic nanoparticle in the extreme near-field regime. The metal is modeled using a nonlocal dielectric function that accounts for the microscopic length scales of the free electron gas. We describe quantitatively the crossover between the macroscopic and microscopic regimes and the enhanced nonradiative decay due to microscopic interactions. Our theory is in agreement with results previously established in the asymptotic near- and far-field regimes.

  Radiative corrections to the polarizability tensor of an electrically small anisotropic dielectric particle

Opt Express. 2010 Feb 15;18(4):3556-67.

Authors
Albaladejo S, Gómez-Medina R, Froufe-Pérez LS, Marinchio H, Carminati R, Torrado JF, Armelles G, García-Martín A, Sáenz JJ.
Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain.


Abstract
Radiative corrections to the polarizability tensor of isotropic particles are fundamental to understand the energy balance between absorption and scattering processes. Equivalent radiative corrections for anisotropic particles are not well known. Assuming that the polarization within the particle is uniform, we derived a closed-form expression for the polarizability tensor which includes radiative corrections. In the absence of absorption, this expression of the polarizability tensor is consistent with the optical theorem. An analogous result for infinitely long cylinders was also derived. Magneto optical Kerr effects in non-absorbing nanoparticles with magneto-optical activity arise as a consequence of radiative corrections to the electrostatic polarizability tensor.

  Fluorescence signal of a single emitter coupled to a nanoparticle through a plasmonic film


J. Opt. A: Pure Appl. Opt. 11 (2009) 114007

Authors
C Vandenbem1,2 , L S Froufe-Perez, 3 and R Carminati 1
1 Institut Langevin, ESPCI, CNRS UMR 7587, Laboratoire d’Optique Physique, 10 rue Vauquelin, F-75231 Paris Cedex 05, France
2 Research Center in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
3 Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain

E-mail: remi.carminati@espci.fr

Abstract
We study theoretically the detection of the fluorescence intensity emitted by a single emitter coupled to a nanoparticle through a metallic thin film. The coupling results from the overlap of the surface plasmon modes propagating on each interface of the film. We show that the distance between the nanoparticle and the film can be used to tune the apparent quantum yield and the radiation pattern with nanometer-scale sensitivity. Such a system is appealing from the experimental point of view since it involves simple structures that can be controlled using current scanning near-field optical techniques. It could be used to improve the detection sensitivity of molecules embedded in substrates, or to design sensitive biological or chemical plasmonic sensors.


  Magneto-optic enhancement and magnetic properties in Fe antidot films with hexagonal symmetry


Physical Review B 81, 054424 (2010)

Authors
E. Th. Papaioannou1, V. Kapaklis1, P. Patoka2, M. Giersig3, P. Fumagall3, A. Garcia-Martin4, E. Ferreiro-Vila4, G. Ctistis5
1 Department of Physics and Astronomy, Materials Physics Division, Uppsala University, Box 516, 751 20 Uppsala, Sweden
2 Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
3 Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
4 Instituto de Microelectrònica de Madrid (IMM), CNM–CSIC, 28760 Madrid, Spain
5 FOM Institute for Atomic and Molecular Physics (AMOLF), Center for Nanophotonics, 1098 XG Amsterdam, The Netherlands


Abstract
The magneto-optic and magnetic properties of hexagonal arrays of holes in optically thin iron films are presented. We analyze their dependence on the hole radius and compare the results to a continuous iron film of the same thickness. We observe a large enhancement of the magneto-optic Kerr rotation with respect to that of the continuous film, at frequencies where surface-plasmon excitations are expected. The spectral position of the Kerr maxima can be tuned by the size and the distance between the holes. Additional simulations are in very good agreement with the experiment and thus confirm the effect of the surface plasmons on the Kerr rotation. The altering of the magnetic properties by the hole array is also visible in the hysteretic behavior of the sample where a significant hardening is observed.


  Active magneto-plasmonics in hybrid metal–ferromagnet structures


Nature Photonics | VOL 4 | FEBRUARY 2010

Authors
Vasily V. Temnov1 *, Gaspar Armelles2, Ulrike Woggon3, Dmitry Guzatov4, Alfonso Cebollada2, Antonio Garcia-Martin2, Jose-Miguel Garcia-Martin2, Tim Thomay5, Alfred Leitenstorfer5 and Rudolf Bratschitsch 5
1 Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
2 Instituto de Microelectronica de Madrid-IMM (CNM-CSIC), 28760 Tres Cantos, Madrid, Spain
3 Institut fur Optik und Atomare Physik, TU Berlin, Strasse des 17. Juni 135, 10632 Berlin, Germany
4 Yanka Kupala Grodno State University, 230023 Grodno, Belarus
5 Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany

*e-mail: temnov@mit.edu


Abstract
Surface-plasmon-mediated confinement of optical fields holds great promise for on-chip miniaturization of all-optical circuits 1–4 . Following successful demonstrations of passive nanoplasmonic devices 5–7 , active plasmonic systems have been designed to control plasmon propagation. This goal has been achieved either by coupling plasmons to optically active materials 8–13 or by making use of transient optical nonlinearities in metals via strong excitation with ultrashort laser pulses 14–17 . Here, we present a new concept in which the active optical component is a metal–ferromagnet–metal structure. It is based on active magneto-plasmonic microinterferometry, where the surface plasmon wave vector in a gold–ferromagnet–gold trilayer system is controlled using a weak external magnetic field. Application of this new technique allows measurement of the electromagnetic field distribution inside a metal at optical frequencies and with nanometre depth resolution. Significant modulation depth combined with possible all-optical magnetization reversal induced by femtosecond light pulses 18 opens a route to ultrafast magneto-plasmonic switching.

  Magneto-optical effects in interacting localized and propagating surface plasmon modes

Optics Express 15635 Vol. 18, No. 15 (2010)

Authors
Jorge F. Torrado, Juan B. Gonzalez-Diaz, Maria U. Gonzalez, Antonio Garcia-Martin, and Gaspar Armelles
Instituto de Microelectronica de Madrid, IMM (CNM-CSIC) PTM, 28760-Tres Cantos (Madrid), Spain


Abstract
We report that the effect of an external magnetic field on the propagation of surface plasmons can be effectively modified through the coupling between localized (LSP) and propagating (SPP) surface plasmons. When these plasmon modes do not interact, the main effect of the magnetic field is a modification of the wavevector of the SPP mode, leaving the LSP virtually unaffected. Once both modes start to interact, there is a strong variation of the magnetic field induced modification of the SPP dispersion curve and, simultaneously, the LSP mode becomes sensitive to the magnetic field.

  Intertwined magneto-optical and plasmonic effects in Ag/Co/Ag layered structures

Physical Review B 80, 125132 (2009)

Authors
Elías Ferreiro-Vila, Juan B. González-Díaz, Rui Fermento, María U. González, Antonio García-Martín, José M. García-Martín, Alfonso Cebollada, and Gaspar Armelles
Instituto de Microelectronica de Madrid, IMM (CNM-CSIC) PTM, 28760-Tres Cantos (Madrid), Spain


Abstract
Surface plasmon polariton (SPP) excitation effects on the magneto-optical (MO) activity of Au capped Ag/Co/Ag trilayers are studied as a function of Co thickness. An enhancement of the transverse MO Kerr signal under SPP excitation as compared with that obtained without SPP excitation is measured with a maximum value of 150 times obtained for the trilayer with 8 nm Co. Such enhancement on the magneto-optical activity due to SPP excitation is also five times higher than that obtained in Au/Co/Au trilayers in similar conditions. The lower optical absorption in the studied range and the sharper plasmon resonance of Ag vs Au are responsible for these values. On the other hand, magnetic field-induced SPP wavevector modulation (Ak/kSPP) is studied for these trilayers and compared both with previous results in the Au/Co/Au system as well as with the theory. In the wavelength considered here, the obtained values are similar for both Ag- and Au-based structures and on the order of 10−4 , pinpointing the role of the magnetic layer on the SPP wavevector modulation.

  Magnetoplasmonic nanostructures: systems supporting both plasmonic and magnetic properties

J. Opt. A: Pure Appl. Opt. 11 (2009) 114023

Authors
G Armelles, A Cebollada, A Garcıa-Martın, J M Garcıa-Martın,M U  Gonzalez, J B Gonzalez-Dıaz, E Ferreiro-Vila and J F Torrado
Instituto de Microelectronica de Madrid, IMM (CNM-CSIC) PTM, 28760-Tres Cantos (Madrid), Spain


Abstract
We present in this work our current understanding on magnetoplasmonic structures, that is, systems whose constituents exhibit simultaneously magnetic and plasmonic properties. We analyze both the influence of the plasmon resonance on the magneto-optical properties of the system and the ability of the magnetic field to modulate the plasmon properties. In particular we show how, in magnetoplasmonic systems sustaining localized or propagating surface plasmons, the associated electromagnetic field enhancement gives rise to an enhancement of the magneto-optical activity. On the other hand, we have analyzed the modulation of the propagating surface plasmon polariton wavevector in noble metal/ferromagnet/noble metal trilayers by an external magnetic field. These phenomena can be addressed as new concepts for the development of active plasmonic devices.

  Plasmon-enhanced magneto-optical activity in ferromagnetic membranes

Applied Physics Letters 94, 263101 (2009)

Authors
J. B. González-Díaz, 1 J. M. García-Martín, 1,a) A. García-Martín, 1 D. Navas, 2,3 A. Asenjo, 2 M. Vázquez, 2 M. Hernández-Vélez, 4 and G. Armelles 1
1 Instituto de Microelectronica de Madrid, IMM (CNM-CSIC) PTM, 28760-Tres Cantos (Madrid), Spain
2 Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain
3 Department of Materials Science and Engineering, MIT, Cambridge, Massachussetts 02139, USA
4 Departamento de Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain

a) Electronic mail: jmiguel@imm.cnm.csic.es


Abstract
Experimental and theoretical evidence of plasmon-enhanced Kerr rotation in purely ferromagnetic membranes with sufficiently small dimensions to be out of extraordinary optical transmission conditions (45 nm pore diameter, 90nm lattice constant), is reported in this work. It is shown that the spectral location of the enhanced Kerr rotation region varies as the refractive index of the material inside the pore is modified. A similar behavior is obtained if the pore radius changes while keeping the pore concentration unchanged. Those are clear signatures indicating that localized surface plasmon resonances propagating along the pores govern the magneto-optical response of the membrane.

  Photocoercivity of nano-stabilized Au: Fe superparamagnetic nanoparticles

Adv Mater. 2010 Sep 22;22(36):4054-8

Authors
Bogani L, Cavigli L, de Julián Fernández C, Mazzoldi P, Mattei G, Gurioli M, Dressel M, Gatteschi D.
1 Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550, Stuttgart, Germany


Abstract
We demonstrate light-induced switching of the coercive field of true nano-stabilized Au:Fe nanoparticles with exceptionally good magneto-optical response. Two separate processes are identified, both exploitable for photocommutation. This innovative material allows combining appealing photoswitching properties with the advantages of traditional metallic nanoparticles, opening the way to new multifunctional nanostructures.

 3D near-field optical characterization of gold/silica nanocomposite thin film


Authors
Loic Lalouat, 1 Laurent Billot, 1 Lionel Aigouy, 1,* Francesco Pineider, 2 César de Julián Fernández, 2 Jessica Labéguerie-Egéa, 3 and Michel Mortier 3
1 Laboratoire de Physique et d’Etude des Matériaux, UMR 8213 ESPCI / CNRS / UPMC 10 rue Vauquelin, 75231 Paris Cedex 5, France
2 Dipartimento di Chimica, Università di Firenze and INSTM Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy
3 Laboratoire de Chimie de la matière Condensée de Paris, UMR CNRS 7574, ENSCP, 11 rue Pierre et Marie Curie, 75005 Paris, France

* Corresponding author: lionel.aigouy@espci.fr


Abstract
We characterized the near-field optical properties of clusters of gold nanoparticles randomly distributed under a 50 nm-thick SiO2 thin film. Although the particles are buried under the dielectric layer, and although our experiments are performed outside the plasmon resonance of the particles, we clearly observed strong lateral variations of the local electromagnetic field, with bright and dark spots. The shape of the bright spots strongly depends on the incident polarization direction and their position is not always above the gold cluster showing the presence of coupling effects between them. The vertical extension of the field strongly depends on the cluster size. For a cluster size between 50 nm and 150 nm, the field variations are confined at a sub-wavelength distance from the surface. However, for a cluster size between 150 nm and 300 nm, the field distribution remains inhomogeneous even at 2λ from the surface. 2010 Optical Society of America

 Plasmon induced modification of the transverse magneto-optical response in Fe antidot arrays


Authors
J. F. Torrado 1 , E. Th. Papaioannou 2 , G. Ctistis 3 , P. Patoka 4 , M. Giersig 4 , G. Armelles 1 , and A. Garcia-Martin *, 1
1 IMM – Instituto de Microelectrónica de Madrid (CNM-CSIC), Isaac Newton 8, PTM, 28760 Tres Cantos, Madrid, Spain
2 Department of Physics and Astronomy, Uppsala University, 75121 Uppsala, Sweden
3 Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, The Netherlands
4 Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany

* Corresponding author: e-mail antonio@imm.cnm.csic.es


Abstract
In this Letter we present the effects that the excitation of plasmon-like modes in periodically perforated Fe films have over the Transverse Magneto-Optical Kerr Effect (TMOKE). The excitation of the modes gives rise to clear signatures in the TMOKE spectra. We analyze the spectral position of the structures as a function of both the polar and azimuth angle.

 Plasmon-Induced Magneto-Optical Activity in Nanosized Gold Disks


Authors
B. Sepulveda, 1 J. B. Gonzalez-Dıaz, 2 A. Garcıa-Martın, 2 L. M. Lechuga, 1 and G. Armelles 2, *
1 Research Center on Nanoscience and Nanotechnology-CIN2 (CSIC) and CIBER-BBN, 08196 Bellaterra, Spain
2 IMM-Instituto de Microelectronica de Madrid (CNM-CSIC), Isaac Newton 8, PTM, E-28760 Tres Cantos, Madrid, Spain


* Corresponding author: e-mail gaspar@imm.cnm.csic.es


Abstract
In this Letter we show that nanostructures made out of pure noble metals can exhibit measurable magneto-optic activity at low magnetic fields. This phenomenon occurs when the localized surface plasmon resonance of the nanostructure is excited in the presence of a static magnetic field parallel to the propagation of incident light. The large magneto-optical response observed comes from an increase of the magnetic Lorentz force induced by the large collective movement of the conduction electrons in the nanostructures when the resonance is excited.

 Coupling between magnetic and optical properties of stable Au–Fe solid solution nanoparticles


Authors
C de Julian Fernandez 1,5 , G Mattei 2 , E Paz 3 , R L Novak 1,6 , L Cavigli 4 , L Bogani 1,7 , F J Palomares 3 , P Mazzoldi 2 and A Caneschi 1
1 INSTM RU at the Department of Chemistry of the University of Firenze, via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
2 Department of Physics, CNISM and University of Padova, via Marzolo 8, 35131 Padova, Italy
3 Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid, Spain
4 Department of Physics—LENS, University of Florence, via Sansone 1, 50019 Sesto Fiorentino, Italy


* Corresponding author: e-mail: cesar.dejulian@unifi.it


Abstract
Au–Fe nanoparticles constitute one of the simplest prototypes of a multifunctional nanomaterial that can exhibit both magnetic and optical (plasmonic) properties. This solid solution, not feasible in the bulk phase diagram in thermal equilibrium, can be formed as a nanostructure by out-of-equilibrium processes. Here, the novel magnetic, optical and magneto-optical properties of ion-implanted Au–Fe solid solution nanoparticles dispersed in a SiO2 matrix are investigated and correlated. The surface plasmon resonance of the Au–Fe nanoparticles with almost equicomposition is strongly damped when compared to pure Au and to Au-rich Au–Fe nanoparticles. In all cases, the Au atoms are magnetically polarized, as measured by x-ray magnetic circular dichroism, and ferromagnetically coupled with Fe atoms. Although the chemical stability of Au–Fe nanoparticles is larger than that of Fe nanoparticles, both the magnetic moment per Fe atom and the order temperature are smaller. These results suggest that electronic and magnetic properties are more influenced by the hybridization of the electronic bands in the Au–Fe solid solution than by size effects. On the other hand, the magneto-optical transitions allowed in the vis–nIR spectral regions are very similar. In addition, we also observe, after studying the properties of thermally treated samples, that the Au–Fe alloy is stabilized, not by surface effects, but by the combination of the out-of-equilibrium nature of the ion implantation technique and by changes in the properties due to size effects.

 Exchange bias in laterally oxidized Au/Co/Au nanopillars


Authors
Ll. Balcells, 1 B. Martinez, 1,a) O. Iglesias, 2 J. M. García-Martín, 3 A. Cebollada, 3 A. García-Martín, 3 G. Armelles, 3 B. Sepúlveda, 4 and Y. Alaverdyan 5
1 Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC), 08193 Bellaterra, Spain
2 Departament de Física Fonamental, Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
3 Instituto de Microelectrónica de Madrid, IMM (CNM-CSIC), 28760 Tres Cantos, Spain
4 Research Center of Nanoscience and Nanotechnology (CIN2-ICN/CSIC), 08193 Bellaterra, Spain
5 Cavendish Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom


* Corresponding author: e-mail: ben.martinez@icmab.es


Abstract
Au/Co/Au nanopillars fabricated by colloidal lithography of continuous trilayers exhibit an enhanced coercive field and the appearance of an exchange bias field with respect to the continuous layers. This is attributed to the lateral oxidation of the Co interlayer that appears upon disk fabrication. The dependence of the exchange bias field on the Co nanodots size and on the oxidation degree is analyzed and its microscopic origin clarified by means of Monte Carlo simulations based on a model of a cylindrical dot with lateral core/shell structure.

  Surface plasmon resonances of clustered nanoparticles

Plasmonics (2011) 6:407--412

Authors
Titus Sandu, Daniel Vrinceanu, and Eugen Gheorghiu
1 International Center for Biodynamics, Bucharest, Romania, and Department of Physics, Texas Southern University, Houston, Texas 77004, USA



* Corresponding author: e-mail: egheorghiu@biodyn.ro


Abstract
Linear clusters made by tightly connecting two or more metallic nanoparticles have new types of surface plasmon resonances as compared to isolated nanoparticles. These new resonances are sensitive to the size of the junction and to the number of interconnected particles and are described by eigenmodes of a Boundary Integral Equation (BIE). This formulation allows effective separation of geometric and shape contribution from electric properties of the constituents. Results for particles covered by a thin shell are also provided highlighting ultrasensitive sensing applications. The present analysis sheds a new light on the interpretation of recent experiments.

  Enhancement of the magnetic modulation of surface plasmon polaritons in Au/Co/Au films

Appl. Phys. Lett. 97, 183114 (2010)

Authors
Diana Martín-Becerra1, Juan B. González-Díaz1, Vasily V. Temnov2, Alfonso Cebollada1,Gaspar Armelles1, Tim Thomay3, Alfred Leitenstorfer3, Rudolf Bratschitsch3, Antonio García-Martín1, and María Ujué González1
1 Instituto de Microelectrónica de Madrid (IMM), CNM-CSIC, Isaac Newton 8, PTM, E-28760 Tres Cantos, Madrid, Spain 
2 Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 
3 Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany 


* Corresponding author: e-mail: diana.martin@imm.cnm.csic.es


Abstract
The deposition of a dielectric overlayer on top of Au/Co/Au multilayer films can significantly enhance the magnetic field induced modulation of the surface plasmon polariton (SPP) wave vector. This enhancement is analyzed as a function of the thickness of the dielectric overlayer and the associated SPP electromagnetic field confinement and redistribution. The decrease in SPP propagation distance is taken into account by analyzing an adequate figure of merit.

 Colloidal Au-enhanced surface plasmon resonance imaging: application in a DNA hybridization process

J. Opt. 12 (2010) 035003

Authors
M G Manera 1 , J Spadavecchia, A Taurino and R Rella
1 Istituto per la Microelettronica e i Microsistemi IMM sezione di Lecce, via per Arnesano, I-73100 Lecce, Italy
 

* Corresponding author: e-mail: mariagrazia.manera@le.imm.cnr.it


Abstract
The detection of the DNA hybridization mechanism using monodispersed gold nanoparticles as labels is an interesting alternative to increase the sensitivity of the SPR imaging technique. DNA-modified Au nanoparticles (DNA-Au NPs) containing single-stranded (ss) portions of DNA were prepared by monitoring their monolayer formation by UV–vis spectroscopy. The hybridization process between specific thio-oligonucleotides immobilized on the DNA–Au NPs and the corresponding complementary strands is reported and compared with the traditional hybridization process on properly self-assembled thin gold films deposited on glass substrates.
A remarkable signal amplification is observed, following the incorporation of colloidal Au into a SPR biosensing experiment, resulting in an increased SPR response to DNA–DNA interactions. In particular Fusarium thiolated DNA (5´HS poly(T)15ATC CCT CAA AAA CTG
CCG CT-3) and trichothecenes complementary DNA (5´-AGC GGC AGT TTT TGA GGG AT- 3´) sequences have been explored due to their possible application to agro-industry for the control of food quality.

 Femtosecond surface plasmon interferometry

Optics Express 8424 Vol. 17, No. 10 (2009)

Authors
Vasily V. Temnov 1 , Keith Nelson 1 , Gaspar Armelles 2 , Alfonso Cebollada 2 , Tim Thomay 3 , Alfred Leitenstorfer 3 and Rudolf Bratschitsch 3
1 Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
2 Instituto de Microelectro´nica de Madrid-IMM (CNM-CSIC), 28760 Tres Cantos, Madrid, Spain
3 Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
 

* Corresponding author: e-mail: temnov@mit.edu


Abstract
We demonstrate femtosecond plasmonic interferometry with a novel geometry. The plasmonic microinterferometer consists of a tilted slit-groove pair. This arrangement allows for (i) interferometric measurements at a single wavelength with a single microinterferometer and (ii) unambiguous discrimination between changes in real and imaginary parts of the metal dielectric function. The performance is demonstrated by monitoring the sub-picosecond dynamics of hot electrons in gol.

 Assessment of the Multiphase Interaction between a Membrane Disrupting Peptide and a Lipid Membrane

J. Phys. Chem. B, 2009, 113 (43), pp 14369–14380

Authors
Andreea Olaru†, Mihaela Gheorghiu†, Sorin David†, Thorsten Wohland‡ and Eugen Gheorghiu*†
1 International Centre of Biodynamics, Bucharest, Romania and Department of Chemistry, National University of Singapore, Singapore

* Corresponding author: e-mail: egheorghiu@biodyn.ro


Abstract
Although modeling and experimental approaches to probe antimicrobial peptides−lipid membranes interaction have already been reported, quantitative evaluation of the whole process, including full dissolution of the lipid, is still missing. We report on the real-time assessment of the entire set of stages of melittin−membrane interaction, based on surface plasmon resonance (SPR) measurements, using supported lipid matrices on L1 sensors and long peptide injections. We advance a mathematical model which comprises a set of coupled kinetic equations and relates via the transfer matrix the evolution of lipid and peptide concentrations with the SPR sensorgram. Upon fitting the sensorgrams of melittin injections on POPC lipid matrices, in agreement with literature data, the model provides: association and dissociation rates, concentration thresholds, and evolution within each interacting layer of lipid and peptide concentrations as well as of peptide to lipid ratios. The proposed model combined with appropriate experimental protocols adds new depths to SPR investigation of peptide−lipid interaction offering a quantitative platform for research and controlled design of improved antimicrobial peptides. A wider applicability for quantitative assessment of other pore forming compounds on different lipid matrices is suggested.

  Sensing based on assessment of non-monotonous effect determined by target analyte: Case study on pore-forming compound

Biosensors and Bioelectronics 24 (2009) 3517–3523

Authors
Mihaela Gheorghiu, Andreea Olaru, Aurelia Tar, Cristina Polonschii, Eugen Gheorghiu*
1 International Centre of Biodynamics, 1B Intrarea Portocalelor 060101 Bucharest 6, Romania

* Corresponding author: e-mail: egheorghiu@biodyn.ro


Abstract
A new and exciting biosensing avenue based on assessment of the non-monotonous, concentration dependent effect of pore formation is discussed. A novel kinetic model is advanced to relate surface plasmon resonance (SPR) data with actual concentrations of interacting partners. Lipid modified L1 sensor chip provide the accessible platform for SPR exploration of peptide–membrane interaction, with POPC and melittin as model systems. We show that quantitative assessment of the interaction between an antimicrobial peptide and lipid modified sensors is capable to provide both sensing avenues and detailed mechanistic insights into effects of pore-forming compounds. The proposed model combined with appropriate design of the experimental protocol adds a new depth to the classic SPR investigation of peptide–lipid interaction offering a quantitative platform for detection, improved understanding of the manifold facets of the interaction and for supporting the controlled design of novel antimicrobial compounds. This biosensing approach can be applied to an entire set of pore-forming compounds including antimicrobial peptides and exo-toxins.

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