436 research outputs found
Amphiphilic Gold Nanoparticles: A Biomimetic Tool to Gain Mechanistic Insights into Peptide-Lipid Interactions
No full textFunctional peptides are now widely used in a myriad of biomedical and clinical contexts, from cancer therapy and tumor targeting to the treatment of bacterial and viral infections. Underlying this diverse range of applications are the non-specific interactions that can occur between peptides and cell membranes, which, in many contexts, result in spontaneous internalization of the peptide within cells by avoiding energy-driven endocytosis. For this to occur, the amphipathicity and surface structural flexibility of the peptides play a crucial role and can be regulated by the presence of specific molecular residues that give rise to precise molecular events. Nevertheless, most of the mechanistic details regulating the encounter between peptides and the membranes of bacterial or animal cells are still poorly understood, thus greatly limiting the biomimetic potential of these therapeutic molecules. In this arena, finely engineered nanomaterials—such as small amphiphilic gold nanoparticles (AuNPs) protected by a mixed thiol monolayer—can provide a powerful tool for mimicking and investigating the physicochemical processes underlying peptide-lipid interactions. Within this perspective, we present here a critical review of membrane effects induced by both amphiphilic AuNPs and well-known amphiphilic peptide families, such as cell-penetrating peptides and antimicrobial peptides. Our discussion is focused particularly on the effects provoked on widely studied model cell membranes, such as supported lipid bilayers and lipid vesicles. Remarkable similarities in the peptide or nanoparticle membrane behavior are critically analyzed. Overall, our work provides an overview of the use of amphiphilic AuNPs as a highly promising tailor-made model to decipher the molecular events behind non-specific peptide-lipid interactions and highlights the main affinities observed both theoretically and experimentally. The knowledge resulting from this biomimetic approach could pave the way for the design of synthetic peptides with tailored functionalities for next-generation biomedical applications, such as highly efficient intracellular delivery systems
A pilot experiment of tagging the deep shrimp Aristeus antennatus (Risso, 1816)
No full textA tagging experiment of the blue and red shrimp, Aristeus antennatus was carried out in the Ionian Sea, off Roccella Jonica (RC). The experiment involved 45 shrimps, caught by trawling at night at about 100-150 m in depth. One month after tagging one specimen was recaptured at about 10 nautical miles from the releasing point. As the first case of tagged recaptured deep sea shrimp, this experiment brings important results about the feasibility of experimental studies on displacement and growth and gives the first direct proof of the migratory abilities A. antennatus.No disponibl
Molecular order in self-assembled multilayers of stearic acid
No full textSelf-assembled multilayers of stearic acid were obtained by evaporating a drop of stearic acid dissolved in organic solvent onto a cleaned glass slide. X-ray diffraction and scanning force microscopy (SFM) were used to determine the bulk structure and to study the surface at molecular level. In samples prepared from decane solution, at least two crystalline forms (A + C and B + C, but seldom A + B + C) coexist and the molecules at the surface appear arranged according to a two-dimensional non-centered rectangular lattice. After annealing of the samples at 80 degrees C (slightly above the melting point of stearic acid), the C-form exists singly: accordingly, the molecular arrangement at the surface reverts to an hexagonal pattern. A periodic buckling superstructure is also observed by SFM in non-annealed samples. Moreover, X-ray diffraction results indicate that recrystallization processes occur
History, ecology and trends for artificial reefs of the Ligurian Sea, Italy
No full textFrom 1970 to the present 10 artificial reef sites have been developed in coastal waters of the Ligurian Sea, Italy. They range from Ventimiglia, in the west, to La Spezia, in the east, with the
largest and best known reef complex being located in the Gulf of Genoa at Loano and consisting of 2,745 m3, about 5,200 t of material and covering a surface of 350 ha. Design and construction practices have advanced from an initial, unsuccessful
effort that used automobile bodies (now banned) to current use of custom-designed concrete modules deployed systematically. Funding for reef construction has come since 1983. The earliest aim of reefs was as a physical barrier to protect habitats against illegal otter trawl fishing. Newer objectives include habitat restoration, enhancement of biodiversity and fishing catch, and
research to test materials and designs for physical and ecological performance. Reefs also functions as environmental observation stations, with the invasive species Caulerpa taxifolia (Vahl)
C. Agardh, being recorded on the reef at Alassio
Changes in the anisotropy of oriented membrane dynamics induced by myelin basic protein
No full textWe report recent results showing the evidence of the effect induced by physiological amounts of myelin basic protein (MBP) on the dynamics of dimyristoyl L-a-phosphatidic acid (DMPA) membranes. Incoherent elastic neutron scattering scans, performed over a wide temperature range, have shown that the anisotropy of motions in oriented membranes is significantly enhanced by the presence of MBP
A covalent homodimer probing early oligomers along amyloid aggregation
No full textEarly oligomers are crucial in amyloid aggregation; however, due to their transient nature they are among the least structurally characterized species. We focused on the amyloidogenic protein beta2-microglobulin (β2m) whose early oligomers are still a matter of debate. An intermolecular interaction between D strands of facing β2m molecules was repeatedly observed, suggesting that such interface may be relevant for β2m dimerization. In this study, by mutating Ser33 to Cys, and assembling the disulphide-stabilized β2m homodimer (DimC33), such DD strand interface was locked. Although the isolated DimC33 display a stability similar to wt β2m under native conditions, it shows enhanced amyloid aggregation propensity. Three distinct crystal structures of DimC33 suggest that dimerization through the DD interface is instrumental for enhancing DimC33 aggregation propensity. Furthermore, the crystal structure of DimC33 in complex with the amyloid-specific dye Thioflavin-T pinpoints a second interface, which likely participates in the first steps of β2m aggregation. The present data provide new insight into β2m early steps of amyloid aggregation
Organization of bipolar lipids at the air-water interface
No full textIn this paper we report the results of surface pressure-area measurements and fluorescence microscopy of Langmuir monolayers of bipolar lipids extracted from the thermophilic archaeobacterium Sulfolobus solfataricus. We have analysed the two-dimensional phase behaviour of the polar lipid extract, some of its subfractions and the hydrolytic fractions glycerol dialkyl glycerol tetraether (GDGT) and glycerol dialkyl nonitol tetraether (GDNT) in the temperature range 25-45-degrees-C. For comparison, films of diphytanoyl phosphatidylcholine were also studied. Only the isotherms of the polar lipid extract exhibit a plateau region. The molecular areas of GDGT and GDNT, even at the collapse pressure, are much larger than those of the other lipid fractions. For the former compounds a U-shaped hydrocarbon chain conformation mixed with an extended chain arrangement is suggested, while all the other fractions display always a vertical arrangement
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