Search

Here we report an investigation on conformational changes of Alpha-synuclein (α-syn) and one of its mutations (E46K), whose fibrillar assemblies in neural cells are the molecular hallmark of Parkinsons' disease. By varying the environmental conditions of the two peptides in terms of temperature (21-60°C), the presence of lipid systems (in homogeneous fluid phase or presenting raft-like domains) and nanostructured surfaces, we observed significant secondary structure alterations in both proteins. In order to probe such transitions, we exploited synchrotron µFTIR directly on solid ring-like residues formed immediately upon evaporation. We concluded that high temperatures and the presence of a lipid fluid phase induce a transition from α-helical materials to β-sheet ones (the characteristic conformation of α-syn fibrils) on pristine flat substrates. The presence of lipid rafts hindered this transition. On the other hand, the inclination to form β-sheet phases in the presence of high temperatures or lipid systems was sensitively lowered by drying the proteins on top of nanostructured highly hydrophilic supports which allow a more homogeneous distribution of the analyte throughout the residue. These results and the presented protocol can indeed pave the basis for the structural characterization of this controversially debated protein and of other neurodegenerative peptides. Display Omitted µFTIR investigation of two α-synuclein proteins involved in Parkinson's diseaseHigh temperature and fluid phase of lipid systems favor β-sheet configuration.Hydrophilic nanostructured surfaces hinder the formation of β-sheet material.

Super-hydrophobic (SH) surfaces are bio-inspired, nanotechnology artifacts which feature a reduced friction coefficient whereby they can be used for a number of very practical applications including, on the medical side, the manipulation of biological solutions. These surfaces can be combined with bio-photonic devices to obtain an integrated lab-on-a-chip system where, on a first stage, the SH surface would vehicle or transport the analytes of interest into a small area and, on a second stage, the bio-sensors would permit, in that area, the detection of the solute with the resolution of a single molecule. This novel diagnostic modality offers realistic possibilities for the early detection of cancers. Nevertheless, as it stands, the device still suffers from the severe disadvantage that the exact final position of the solute, upon evaporation, is unpredictable, and thus the localization and recognition of few molecules would be impractical. Conventional SH surfaces typically comprise micro pillars combined to form a regular hexagonal motif. Here, the periodicity of those pillars was broken introducing artificial gradients of wettability over the surface. In doing so, some regions are rendered more hydrophilic than others and, on account of this, a solute would preferentially target these hydrophilic regions upon evaporation. In this work, such non regular geometries were realized and used to condense diluted Rhodamine solutions in a small area. Randomly distributed silver nano aggregates, conveniently positioned upon the micropillars, permitted the identification of few molecules using enhanced Fourier transform infrared spectroscopy (FTIR) spectroscopy.

Superhydrophobic surfaces were fabricated comprising cylindrical micro-pillars arranged in a regular hexagonal lattice. These structures are hierarchical in that the pillars incorporate, on the top, nanoporous silicon films. In sight of the superhydrophobicity of the system, the devices retain the ability of manipulating and concentrating diluted biological solutions, while, on account of the nanoporous films, they would efficiently filter the biological content of such solutions. The major advance, here, is the simultaneous use of the properties above, and thus important applications are envisioned where extremely small quantities of bio-markers are efficiently extracted from serum and analyzed employing conventional and well assessed spectroscopy techniques. Ultra low concentrated small Rhodamine molecules were here efficiently analyzed using FTIR spectroscopy techniques, thus demonstrating that these devices are effective.