Effect of the surface chemical composition and of added metal cation concentration on the stability of metal nanoparticles synthesized by pulsed laser ablation in water

Metal nanoparticles (NPs) made of gold, silver, and platinum have been synthesized by means of pulsed laser ablation in liquid aqueous solution. Independently from the metal nature, all NPs have an average diameter of 10 ± 5 nm. The ζ-potential values are:-62 ± 7 mV for gold,-44 ± 2 mV for silver and-58 ± 3 for platinum. XPS analysis demonstrates the absence of metal oxides in the case of gold and silver NPs. In the case of platinum NPs, 22% of the particle surface is ascribed to platinum oxidized species. This points to a marginal role of the metal oxides in building the negative charge that stabilizes these colloidal suspensions. The investigation of the colloidal stability of gold NPs in the presence of metal cations shows these NPs can be destabilized by trace amounts of selected metal ions. The case of Ag+ is paradigmatic since it is able to reduce the NP ζ-potential and to induce coagulation at concentrations as low as 3 μM, while in the case of K+ the critical coagulation concentration is around 8 mM. It is proposed that such a huge difference in destabilization power between monovalent cations can be accounted for by the difference in the reduction potential

Salting-out approach is worthy of comparison with ultracentrifugation for extracellular vesicle isolation from tumor and healthy models

The role of extracellular vesicles (EVs) has been completely re-evaluated in the recent decades, and EVs are currently considered to be among the main players in intercellular commu-nication. Beyond their functional aspects, there is strong interest in the development of faster and less expensive isolation protocols that are as reliable for post-isolation characterisations as already-established methods. Therefore, the identification of easy and accessible EV isolation techniques with a low price/performance ratio is of paramount importance. We isolated EVs from a wide spectrum of samples of biological and clinical interest by choosing two isolation techniques, based on their wide use and affordability: ultracentrifugation and salting-out. We collected EVs from human cancer and healthy cell culture media, yeast, bacteria and Drosophila culture media and human fluids (plasma, urine and saliva). The size distribution and concentration of EVs were measured by nanoparticle tracking analysis and dynamic light scattering, and protein depletion was measured by a colori-metric nanoplasmonic assay. Finally, the EVs were characterised by flow cytometry. Our results showed that the salting-out method had a good efficiency in EV separation and was more efficient in protein depletion than ultracentrifugation. Thus, salting-out may represent a good alternative to ultracentrifugation

Effect of the Surface Chemical Composition and of Added Metal Cation Concentration on the Stability of Metal Nanoparticles Synthesized by Pulsed Laser Ablation in Water

Metal nanoparticles (NPs) made of gold, silver, and platinum have been synthesized by means of pulsed laser ablation in liquid aqueous solution. Independently from the metal nature, all NPs have an average diameter of 10 ± 5 nm. The ζ-potential values are: −62 ± 7 mV for gold, −44 ± 2 mV for silver and −58 ± 3 for platinum. XPS analysis demonstrates the absence of metal oxides in the case of gold and silver NPs. In the case of platinum NPs, 22% of the particle surface is ascribed to platinum oxidized species. This points to a marginal role of the metal oxides in building the negative charge that stabilizes these colloidal suspensions. The investigation of the colloidal stability of gold NPs in the presence of metal cations shows these NPs can be destabilized by trace amounts of selected metal ions. The case of Ag+ is paradigmatic since it is able to reduce the NP ζ-potential and to induce coagulation at concentrations as low as 3 μM, while in the case of K+ the critical coagulation concentration is around 8 mM. It is proposed that such a huge difference in destabilization power between monovalent cations can be accounted for by the difference in the reduction potential

photochemical activity of the bacterial reaction center in polymer like phospholipids reverse micelles

An integral membrane protein, the photosynthetic bacterial reaction center (RC), has been incorporated in reverse micelle viscoelastic gels made of phosphatidylcholine and phosphatidylserine. Due to the dynamic nature of the gels, the use of a technique which shares the same timescale of the charge recombination is advised, in order to correlate the kinetic behaviour of the RC to the hosting-system properties. Self-diffusion and conductivity measurements have been used to investigate the properties of the model system lecithin/cyclohexane/water. The results indicate that such techniques can describe the properties of the system on a long characteristic time-scale. As a consequence, the kinetic behaviour of the RC has been studied by means of flash-spectro-photometry and related to the structural properties of the hosting gel, investigated by means of conductivity. The conductivity data are consistent with a water-induced sphere-to-rod transition of the phospholipid aggregates. Furthermore, increasing the ratio [water]/[lipid], a maximum in the hydrodynamic dimension of the giant worm-like reverse micelles is found. The experimental P+ decay has been resolved into three exponential components which are strongly affected by the system composition. The functionality of the binding site QB is dependent on the ratio [water]/[lipid] supporting the hypothesis of a water role in the binding process

Survival after laparoscopic and open surgery for colon cancer: a comparative, single-institution study

BACKGROUND: Some recent studies have suggested that laparoscopic surgery for colorectal cancer may provide a potential survival advantage when compared with open surgery. This study aimed to compare cancer-related survivals of patients who underwent laparoscopic or open resection of colon cancer in the same, high volume tertiary center. METHODS: Patients who had undergone elective open or laparoscopic surgery for colon cancer between January 2002 and December 2010 were analyzed. A clinical database was prospectively compiled. Survival analysis was calculated by using the Kaplan-Meier method. RESULTS: A total of 460 resections were performed. There were no significant differences between the laparoscopic (n = 227) and the open group (n = 233) apart from tumor stage: stage I tumors were more frequent in the laparoscopic group whereas stage II tumors were more frequent in the open group. The mean number of harvested lymph nodes was significantly higher in the laparoscopic than in the open group (20.0 ± 0.7 vs 14.2 ± 0.5, P < 0.01). The 5-year cancer-related survival for patients undergoing laparoscopic resection was significantly higher than that following open resections (83.1% vs 68.5%, P = 0.01). By performing a stage-to-stage comparison, we found that the improvement in survival in the laparoscopic group occurred mainly in patients with stage II tumors. CONCLUSIONS: Our study shows a survival advantage for patients who had undergone laparoscopic surgery for stage II colon cancer. This may be correlated with a higher number of harvested lymph nodes and thus a better stage stratification of these patients

Use of lipid bilayers as support for biomolecules integration in OTFT biosensors

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Interpretation and chronostratigraphic mapping of multichannelseismic reflection profile I95167,Eastern Falkland Plateau (South Atlantic)

The Falkland Plateau (FP) is a submarine high representing the eastern prolongation of the South America continent. Itseparates the Argentine Basin of the South Atlantic Ocean from the Scotia Sea of the Antarctic region. A south\u2013north seismicsection across the Falkland Plateau has been interpreted using information from two wells sited on the margin of the MauriceEwing Bank (MEB). On the Plateau, the sedimentary cover has a regionally horizontal configuration with high lateral continuityof the reflecting horizons. The older sequence is dominated by a normal fault system of the Mesozoic Gondwana break-uptectonics, partially reactivated by the following tectonic events. Between them, the one mainly affecting the studied area is thetranspression of the North Scotia Ridge (NSR), producing some thrusting in the sedimentary cover of the Falkland Trough (FT,visible only on the south-extremity of the interpreted section) and a prominent tilting of its whole crust. The interpreted seismicsection outlines a gradually thinner crust from the Maurice Ewing Bank Margin to the Falkland Plateau and to the FalklandTrough. During the interpretation, particular attention was given to picking the main unconformities, to analysing therelationships of reflections within the sequences to the unit boundaries, and to identifying, by the seismic facies analysis, thedifferent depositional units. These last, labelled with symbols AH G, from Mesozoic to Present age, represent the wholesedimentary cover lying on the pre-Cambrian basement of the Falkland Plateau. In the reconstructed chronostratigraphic section,the whole data set has been displayed as a diagram wherein age decreases upward and the lateral extent of units is on thehorizontal scale, illustrating the main sedimentary and erosional events in the area. Erosion, nondeposition and deposition ofsediment drifts by the sea bottom currents, particularly active from the Cainozoic to the Present, are mostly linked to theGondwana breakup, with the Mesozoic opening of the South Atlantic Ocean and the Cainozoic opening of the Drake Passage.During the Mesozoic time, the Proto-South Atlantic and Indian Oceans connection caused extensive erosion and nondeposition,resulting in absence of important portions of the sedimentary cover