Chiral materials with non linear optical properties can be found also among biological molecules presenting an ordered arrangement and non-inversion-symmetric structure in space, or having a chromophore. The latter group, called chromoproteins, is best represented by bacteriorhodopsin (BR), one of the most studied biomolecules exhibiting NLO properties [1]. We have studied BR in its purple membrane bound form by producing a 15  thick oriented film via electrophoretic deposition onto a glass substrate covered by a 60nm thick ITO film. The resulting BR films, composed by ~2600 purple membrane layers (of 5nm thickness each) were characterized in terms of homogeneity, optical and electrical properties. In order to study the coherence optical response of BR we performed parametric nonlinear interaction (second harmonic generation (SHG) measurements) in noncollinear configuration. The noncollinear scheme with two input pump beams, offer very high flexibility in the handling and control the SHG signal which becomes selectively addressed by choosing the appropriate polarization state for the fundamental beams [2].The noncollinear second harmonic generation from the BR film was obtained using the output of a mode-locked femtosecond Ti:Sapphire laser system tuned at ï¬=830 nm (76 MHz repetition rate, 130 fs pulse width, average power of 500 mW) which was split into two beams of about the same intensity. The coherence of the interaction can be handled by an additional input beam in the absorption regime. The presence of the nonlinear magnetization and its contribution to the SHG signal, can be also tuned and modulated by the application of an external static magnetic field of moderate intensity. References [1] F.A.Bovino, MC Larciprete, C Sibilia, G.Varo, C.Gergely ,Optics Express, 20,14621 (2012) [2] M.C Larciprete, F A Bovino, M Giardina, A Belardini, M Centini, C Sibilia, M Bertolotti, A Passaseo, V Tasco, Optics Letters 34: 2189 (2009)

The possibility to engineer bio-nanomaterials with programmed synthesis and controlled immobilization of biomolecules through biomimetic molecular evolution approach has been demonstrated. Material specific peptides with exquisite molecular recognition function were used as a linker for the attachment of biomolecules. Exploring the origin of peptide material specificity not only opens up rational design approach with precise control over biomimetic bio-sensor design, but more importantly provides a new route of functionalizing for various material surfaces with enhanced sensitivity over classical grafting chemistry. To study the fine prints of experimentally obtained peptides, theoretical understanding of surface interactions may serve as important clues for further refinement. By taking advantage of classical molecular dynamics (MD) simulations and density functional theory (DFT), we investigated the origin of this smart recognition function through the strength of interaction of experimentally selected 12mer peptides revealing high binding affinity towards n+-Si(100). Here, we attempt for the very first time to model the interaction of the peptides (in buffer solution) with semiconductors and we calculate their binding energies at the atomic level, enabling thereby linking direct evidence to our experimental evidence. Several peptide conformations have been taken into account simultaneously upon the surface. Our studies demonstrate that the peptides possess certain recognition function and their high interaction energy with the surface makes them unique among the populations. Our work is a step towards the understanding of the interactions between peptides and semiconductor surfaces that is a highly relevant challenge in the development of novel devices with a high degree of biocompatibility as well.

Confocal Raman microscopy is a noninvasive, label-free imaging technique used to study apoptosis of live MCF-7 cells. The images are based on Raman spectra of cells components, and their apoptosis is monitored through diffusion of cytochrome c in cytoplasm. K-mean clustering is used to identify mitochondria in cells, and correlation analysis provides the cytochrome c distribution inside the cells. Our results demonstrate that incubation of cells for 3 h with 10 μM of paclitaxel does not induce apoptosis in MCF-7 cells. On the contrary, incubation for 30 min at a higher concentration (100 μM) of paclitaxel induces gradual release of the cytochrome c into the cyto- plasm, indicating cell apoptosis via a caspase independent pathway.

We use atomic force microscopy (AFM) to study the morphological and nanomechanical properties of mice dorsal root ganglia sensory neurons in regenerative growth mode. A prior peripheral nerve injury in vivo, promotes a rapid elongated mode of sensory neurons neurite regrowth in vitro. Complementary differential interference contrast microscopy results show that conditioned axotomy, induced by sciatic nerve injury, did not increase somatic size of adult lumbar sensory neurons but promoted the appearance of larger growth cones. Our AFM data indicate that neurons having a regenerative growth are characterized by softer growth cones, compared to control neurons. The increase of the growth cone membrane elasticity suggests a modification in the ratio and the inner framework of the main structural proteins.

The aim of this work is to demonstrate the sensing ability of reverse-symmetry waveguides to investigate adsorption of casein and build-up of poly-L-lysine mediated casein multilayers. A first part of this study is dedicated to the elaboration and characterization of ultra-porous thin films with very low refractive indices by an appropriate sol-gel method. This will form the basis of our planar optical sensors. Optical waveguide light mode spectroscopy is a real-time and sensitive method to study protein adsorption kinetics and lipid bilayers. We used it to test the obtained waveguides for in-situ monitoring of biomolecule adsorption. As a result, significant changes in the incoupling peak position were observed during the layer-by-layer adsorption. Finally, refractive index and thickness of the adsorbed layers were established.

Confocal Raman microscopy, a non-invasive, label-free, and high spatial resolution imaging technique is employed to trace the anticancer drug paclitaxel in living Michigan Cancer Foundation- 7 (MCF-7) cells. The Raman images were treated by K-mean cluster analysis to detect the drug in cells. Distribution of paclitaxel in cells is verified by calculating the correlation coefficient between the reference spectrum of the drug and the whole Raman image spectra. A time dependent gradual diffusion of paclitaxel all over the cell is observed suggesting a complementary picture of the pharmaceutical action of this drug based on rapid binding of free tubulin to crystallized paclitaxel.