Sulfonated Pentablock Copolymer Coating of Polypropylene Filters for Dye and Metal Ions Effective Removal by Integrated Adsorption and Filtration Process.

In this work, we coated polypropylene (PP) fibrous filters with sulfonated pentablock copolymer (s-PBC) layers and tested them for the removal of cationic organic dyes, such as methylene blue (MB), and heavy metal ions (Fe3+ and Co2+) from water by adsorption and filtration experiments. Some of the coated filters were irradiated by UV light before being exposed to contaminated water and then were tested with unirradiated filters in the same adsorption and filtration experiments. Polymer-coated filters showed high efficiency in removing MB from an aqueous solution in both absorption and filtration processes, with 90% and 80% removal, respectively. On the other hand, for heavy metal ions (Fe3+ and Co2+), the coated filters showed a better removal performance in the filtration process than for the adsorption one. In fact, in the adsorption process, controlled interaction times allow the ionic species to interact with the surface of the filters leading to the formation and release of new species in solution. During filtration, the ionic species are easily trapped in the filters, in particular by UV modified filters, and we observed for Fe3+ ions a total removal (>99%) in a single filtration process and for Co2+ ions a larger removal with respect to the untreated filter. The mechanisms involved in the removal of the contaminants processes were investigated by characterizing the filters before and after use by means of scanning electron microscopy (SEM) combined with energy-dispersive X-ray (EDX) analysis and Fourier transform infrared spectroscopy (FT-IR).

Antimicrobial s-PBC Coatings for Innovative Multifunctional Water Filters.

Biological contamination is a typical issue in water treatment. Highly concentrated microbial suspensions in a water flow may cause filter occlusion and biofilm formation, affecting the lifespan and quality of water purification systems and increasing the risk of nosocomial infections. In order to contrast the biofilm formation, most of the conventional strategies rely on the water chemical modification and/or on the use of filters functional coatings. The former is unsafe for huge chemicals spilling required; therefore, we focus on the second approach and we propose the use of a sulfonated pentablock copolymer (s-PBC, commercially named Nexar™) as innovative multifunctional coating for improving the performance of commercial water filters. S-PBC-coated polypropylene (PP) samples were tested against the pathogen Pseudomonas aeruginosa. The covering of PP with s-PBC results in a more hydrophilic, acid, and negatively charged surface. These properties avoid the adhesion and proliferation attempts of planktonic bacteria, i.e., the biofilm formation. Inhibition tests were performed on the as-modified filters and an evident antibacterial activity was observed. The results point out the possibility of using NexarTM as coating layer for filters with antifouling properties and a simultaneous ability to remove bacteria and cationic dyes from water.

Trehalose Conjugates of Silybin as Prodrugs for Targeting Toxic Aß Aggregates.

Alzheimer's disease (AD) is linked to the abnormal accumulation of amyloid ß peptide (Aß) aggregates in the brain. Silybin B, a natural compound extracted from milk thistle (Silybum marianum), has been shown to significantly inhibit Aß aggregation in vitro and to exert neuroprotective properties in vivo. However, further explorations of silybin B's clinical potential are currently limited by three main factors: (a) poor solubility, (b) instability in blood serum, and (c) only partial knowledge of silybin's mechanism of action. Here, we address these three limitations. We demonstrate that conjugation of a trehalose moiety to silybin significantly increases both water solubility and stability in blood serum without significantly compromising its antiaggregation properties. Furthermore, using a combination of biophysical techniques with different spatial resolution, that is, TEM, ThT fluorescence, CD, and NMR spectroscopy, we profile the interactions of the trehalose conjugate with both Aß monomers and oligomers and evidence that silybin may shield the "toxic" surfaces formed by the N-terminal and central hydrophobic regions of Aß. Finally, comparative analysis with silybin A, a less active diastereoisomer of silybin B, revealed how even subtle differences in chemical structure may entail different effects on amyloid inhibition. The resulting insight on the mechanism of action of silybins as aggregation inhibitors is anticipated to facilitate the future investigation of silybin's therapeutic potential.

Strategy to discover full-length amyloid-beta peptide ligands using high-efficiency microarray technology.

Although the formation of ß-amyloid (Aß) fibrils in neuronal tissues is a hallmark of Alzheimer disease (AD), small-sized Aß oligomers rather than mature fibrils have been identified as the most neurotoxic species. Therefore, the design of new inhibitors, able to prevent the aggregation of Aß, is believed to be a promising therapeutic approach to AD. Unfortunately, the short-lived intermediate structures that occur in a solution along the Aß aggregation pathway escape conventional experimental investigations and there is urgent need of new tools aimed at the discovery of agents targeting monomeric Aß and blocking the early steps of amyloid aggregation. Here, we show the combination of high-efficiency slides (HESs) with peptide microarrays as a promising tool for identifying small peptides that bind Aß monomers. To this aim, HESs with two immobilized reference peptides, (i.e., KLVFF and Semax) with opposite behavior, were investigated for binding to fluorescently labeled Aß peptide. Transmission electron microscopy was used to demonstrate Aß fibrillar aggregates missing. The use of HESs was critical to ensure convenient output of the fluorescent microarrays. The resulting sensitivity, as well as the low sample consumption and the high potential for miniaturization, suggests that the proposed combination of peptide microarrays and highly efficient slides would be a very effective technology for molecule profiling in AD drug discovery.

Inhibition of Aß Amyloid Growth and Toxicity by Silybins: The Crucial Role of Stereochemistry.

The self-assembling of the amyloid ß (Aß) peptide into neurotoxic aggregates is considered a central event in the pathogenesis of Alzheimer's disease (AD). Based on the "amyloid hypothesis", many efforts have been devoted to designing molecules able to halt disease progression by inhibiting Aß self-assembly. Here, we combine biophysical (ThT assays, TEM and AFM imaging), biochemical (WB and ESI-MS), and computational (all-atom molecular dynamics) techniques to investigate the capacity of four optically pure components of the natural product silymarin (silybin A, silybin B, 2,3-dehydrosilybin A, 2,3-dehydrosilybin B) to inhibit Aß aggregation. Despite TEM analysis demonstrated that all the four investigated flavonoids prevent the formation of mature fibrils, ThT assays, WB and AFM investigations showed that only silybin B was able to halt the growth of small-sized protofibrils thus promoting the formation of large, amorphous aggregates. Molecular dynamics (MD) simulations indicated that silybin B interacts mainly with the C-terminal hydrophobic segment 35MVGGVV40 of Aß40. Consequently to silybin B binding, the peptide conformation remains predominantly unstructured along all the simulations. By contrast, silybin A interacts preferentially with the segments 17LVFF20 and 27NKGAII32 of Aß40 which shows a high tendency to form bend, turn, and ß-sheet conformation in and around these two domains. Both 2,3-dehydrosilybin enantiomers bind preferentially the segment 17LVFF20 but lead to the formation of different small-sized, ThT-positive Aß aggregates. Finally, in vivo studies in a transgenic Caenorhabditis elegans strain expressing human Aß indicated that silybin B is the most effective of the four compounds in counteracting Aß proteotoxicity. This study underscores the pivotal role of stereochemistry in determining the neuroprotective potential of silybins and points to silybin B as a promising lead compound for further development in anti-AD therapeutics.

High sensitivity protein assays on microarray silicon slides.

In this work, we report on the improvement of microarray sensitivity provided by a crystalline silicon substrate coated with thermal silicon oxide functionalized by a polymeric coating. The improvement is intended for experimental procedures and instrumentations typically involved in microarray technology, such as fluorescence labeling and a confocal laser scanning apparatus. The optimized layer of thermally grown silicon oxide (SiO(2)) of a highly reproducible thickness, low roughness, and fluorescence background provides fluorescence intensification due to the constructive interference between the incident and reflected waves of the fluorescence radiation. The oxide surface is coated by a copolymer of N,N-dimethylacrylamide, N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)propyl methacrylate, copoly(DMA-NAS-MAPS), which forms, by a simple and robust procedure, a functional nanometric film. The polymeric coating with a thickness that does not appreciably alter the optical properties of the silicon oxide confers to the slides optimal binding specificity leading to a high signal-to-noise ratio. The present work aims to demonstrate the great potential that exists by combining an optimized reflective substrate with a high performance surface chemistry. Moreover, the techniques chosen for both the substrate and surface chemistry are simple, inexpensive, and amenable to mass production. The present application highlights their potential use for diagnostic applications of real clinical relevance. The coated silicon slides, tested in protein and peptide microarrays for detection of specific antibodies, lead to a 5-10-fold enhancement of the fluorescence signals in comparison to glass slides.