Preparation and characterization of Thioflavin T doped silica nanoparticles

Fluorescent silica nanoparticles with diameters of about 300nm were synthesized based on Stober's method, using Thioflavin T as fluorescent co-reagent. The particles were characterized via transmission electron microscopy and fluorimetry measurements. Fluorescence intensity of the sols was ten times higher than that of the ethanol phase solutions of Thioflavin T. Release of dye molecules in stable alcosols was investigated by measuring UV-Vis absorbance spectrum of the supernatant. To try an alternative route, we investigated accumulation of dye molecules in native silica particles. No release effect was detected, and slow accumulation was observed. Water contact angles of the particles were assessed from analyzing the Langmuir films, and were found to be 18, very similar to native silica particles. Langmuir-Blodgett films of the particles were deposited on a glass substrate and were examined via UV-Vis spectrophotometry, fluorimetry and scanning electron microscopy. Presence of the film was revealed; the particles formed a continuous, well-packed monolaye

Self-division of giant vesicles driven by an internal enzymatic reaction

Self-division is one of the most common phenomena in living systems and one of the most important properties of life driven by internal mechanisms of cells. Design and engineering of synthetic cells from abiotic components can recreate a life-like function thus contributing to the understanding of the origin of life. Existing methods to induce the self-division of vesicles require external and non-autonomous triggers (temperature change and the addition of membrane precursors). Here we show that pH-responsive giant unilamellar vesicles on the micrometer scale can undergo self-division triggered by an internal autonomous chemical stimulus driven by an enzymatic (urea-urease) reaction coupled to a cross-membrane transport of the substrate, urea. The bilayer of the artificial cells is composed of a mixture of phospholipids (POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine) and oleic acid molecules. The enzymatic reaction increases the pH in the lumen of the vesicles, which concomitantly changes the protonation state of the oleic acid in the inner leaflet of the bilayer causing the removal of the membrane building blocks into the lumen of the vesicles thus decreasing the inner membrane area with respect to the outer one. This process coupled to the osmotic stress (responsible for the volume loss of the vesicles) leads to the division of a mother vesicle into two smaller daughter vesicles. These two processes must act in synergy; none of them alone can induce the division. Overall, our self-dividing system represents a step forward in the design and engineering of a complex autonomous model of synthetic cells

Colloidal Lithography

This chapter is a visual guide to the numerous approaches to nanolithography nanofabrication on large area based on supramolecular self-assembly. A short history of this recent scientific and technological field, an outline of the most-cited methods of self-assembly, and tables reporting different nanofabrication methods are reported. Indications on requirements, advantages, and drawbacks of the various approaches are also listed in the table. Thanks to the recently developed metal-assisted catalytic etching (MACE), the colloidal patterns can be easily propagated to silicon and other semiconductors opening a wide field of morphology, nanostructures, and applications