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.

A prior peripheral nerve injury in vivo, promotes a rapid elongated mode of sensory neurons neurite regrowth in vitro. This in vitro model of conditioned axotomy allows analysis of the cellular and molecular mechanisms leading to an improved neurite re-growth. Our differential interference contrast microscopy and immunocytochemistry results show that conditioned axotomy, induced by sciatic nerve injury, did not increase somatic size of adult lumbar sensory neurons from mice dorsal root ganglia sensory neurons but promoted the appearance of larger neurites and growth cones. Using atomic force microscopy on live neurons, we investigated whether membrane mechanical properties of growth cones of axotomized neurons were modified following sciatic nerve injury. Our data revealed that neurons having a regenerative growth were 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.

Background: A combinatorial phage display approach was previously used to evolve a 12-mer peptide (SVSVGMKP- SPRP) with the highest affinity for different semiconductor surfaces.Thediscoveryofthemultipleoccurrencesofthe SVSVGMKPSPRP sequence in an all-against-all basic local alignment search tool search of PepBank sequences was unexpected, and a Google search using the peptide sequence recovered 58 results concerning 12 patents and 16 scientific publications. The number of patent and articles indicates that the peptide is perhaps a broad range adhesion peptide. Methods: To evaluate peptide properties, we conducted a study to investigate peptide adhesion on different inor- ganic substrates by mass spectrometry and atomic force microscopy for gold, carbon nanotubes, cobalt, chrome alloy, titanium, and titanium alloy substrates. Results: Our results showed that the peptide has a great potential as a linker to functionalize metallic surfaces if specificity is not a key factor. This peptide is not specific to a particular metal surface, but it is a good linker for the functionalization of a wide range of metallic materials. Conclusion: The fact that this peptide has the potential to adsorb on a large set of inorganic surfaces suggests novel promising directions for further investigation. Affinity determination of SVSVGMKPSPRP peptide would be an important issue for eventual commercial uses.

A recombinant hepatitis B surface antigen (HBsAg) has been produced in the yeast Saccharomyces cere- visiae and used as a vaccine against hepatitis B virus (HBV) infection. The present study aimed to optimize the extraction of recombinant virus-like particles (rVLPs) to develop a simple purification procedure based on gel filtration and high performance size-exclusion chromatography. The findings showed that disruption of yeast cells with alumina powder increased the yield of the total proteins (290 mg/l) and rVLPs (1 mg/l) compared to the values for glass beads (171 mg/l and 0.5 mg/l), as estimated by quantita- tive ELISA. The purification of rVLPs was performed by two consecutive gel filtration chromatographic steps, namely Sephacryl S-200 followed by SEC-250 HPLC. The purified M protein was analyzed by atomic force microscopy and shown to assemble in particles that were able to recognize HBV antibodies in the sera of patients with chronic hepatitis B, providing evidence for their immunoreactivity.

Though, the pharmacological activity of curcumin inhibiting the proliferation of certain cancer cells in culture was demonstrated, its effect on early-stage modifications induced in cell mechanics influencing hereby cell growth and cell adhesion are still questionable. We investigate the morphology and the elastic properties of live cultured, non-malignant human mammalian epithelial cells (HMEC) and cancerous breast epithelial cells (MCF7), using atomic force microscopy (AFM). We describe the different behavior of the two similar cell lines under curcumin treatment and we use fluorescence microscopy to identify the microtubules as the cytoskeleton structures responding to curcumin. The first changes in the HMEC cell morphology are observed after already two hours incubation with curcumin. A six-hour long treatment leaves the MCF7 cells morphology non-affected, but the microtubules of HMEC cells disassemble and form a ring-like organization circumscribing the nuclear area. The observed morphological changes were correlated to modifications in cell's mechanics via elasticity force mapping measurements. Curcumin treatment modified elasticity of the HMEC cells increasing the cell's average Young's modulus two- to three-fold, especially in the cytoplasmic area. Contrariwise, a slight decrease in the Young's modulus was noticed for the MCF7 cells, as they become softer due to the action of curcumin. Chemotherapeutic drugs exert their effect via the perturbation of the dynamic instability of the microtubule, hence the cell specific perturbation induced by curcumin can help in future understanding of drug induced events on the cell behavior.

The purified photosynthetic reaction center protein (RC) from Rhodobacter sphaeroides R-26 purple bacteria was bound to porous silicon microcavities (PSiMc) either through silane-glutaraldehyde (GTA) chemistry or via a noncovalent peptide cross-linker. The characteristic resonance mode in the microcavity reflectivity spectrum red shifted by several nanometers upon RC binding, indicating the protein infiltration into the porous silicon (PSi) photonic structure. Flash photolysis experiments confirmed the photochemical activity of RC after its binding to the solid substrate. The kinetic components of the intraprotein charge recombination were considerably faster (τfast = 14 (±9) ms, τslow = 230 (±28) ms with the RC bound through the GTA cross-linker and only τfast = 27 (±3) ms through peptide coating) than in solution (τfast = 120 (±3) ms, τslow = 1387 (±2) ms), indicating the effect of the PSi surface on the light-induced electron transfer in the protein. The PSi/RC complex was found to oxidize the externally added electron donor, mammalian cytochrome c, and the cytochrome oxidation was blocked by the competitive RC inhibitor, terbutryne. This fact indicates that the specific surface binding sites on the PSi-bound RC are still accessible to external cofactors and an electronic interaction with redox components in the aqueous environment is possible. This new type of biophotonic material is considered to be an excellent model for new generation applications at the interface of silicon-based electronics and biological redox systems designed by nature.