Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

A collection of more than 1800 carbonized papyri, discovered in the Roman ‘Villa dei Papiri’ at Herculaneum is the unique classical library survived from antiquity. These papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains an impressive amount of treatises by Greek philosophers and, especially, Philodemus of Gadara, an Epicurean thinker of 1st century BC. We read many portions of text hidden inside carbonized Herculaneum papyri using enhanced X-ray phase-contrast tomography non-destructive technique and a new set of numerical algorithms for ‘virtual-unrolling’. Our success lies in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of text have been decoded and the ‘voice’ of the Epicurean philosopher Philodemus is brought back again after 2000 years from Herculaneum papyri.

Light manipulation of nanoparticles in arrays of topological defects

We report a strategy to assemble and manipulate nanoparticles arrays. The approach is based on the use of topological defects, namely disclination lines, created in chiral liquid crystals. The control of nanoparticle-loaded topological defects by low power light is demonstrated. Large-scale rotation, translation and deformation of quantum dots light-emitting chains is achieved by homogeneous LED illumination. Full reconfigurability and time stability make this approach attractive for future developments and applications.

Self-assembly of hydrophobin protein rodlets studied with atomic force spectroscopy in dynamic mode

We have investigated the self-assembling properties of the class I hydrophobin Vmh2 isolated from the fungus Pleurotus ostreatus. Five different hydrophobin self assembled samples including monolayers, bilayers, and rodlets have been prepared by Langmuir technique and studied at the nanoscale. Local wettability and visco-elasticity of the different hydrophobins samples were obtained from atomic force spectroscopy experiments in dynamic mode performed at different, controlled relative humidity (RH) values. It was found that hydrophobins assembled either in rodlets or in bilayer films, display similar hydropathicity and viscoelasticity in contrast to the case of monolayers, whose hydropathicity and viscoelasticity depend on the adopted preparation method (Langmuir-Blodgett or Langmuir-Schaeffer). The comparison with monolayers properties evidences a rearrangement of the bilayers adsorbed onto solid substrates. It is shown that this rearrangement leads to the formation of a stable hydrophobic film, and that the rodlets structure consists in fragments of restructured proteins bilayers. Our results support the hypothesis that the observed variations in the viscoelastic properties could be ascribed to the localization of the large flexible loop, typical of Class I hydrophobins which appears free at the air interface for LB monolayers but not for the other samples. These findings should now serve future developments and applications of hydrophobin films beyond the archetypal monolayer.

Bioactive modification of silicon surface using self-assembled hydrophobins from Pleurotus ostreatus

A crystalline silicon surface can be made biocompatible and chemically stable by a self-assembled biofilm of proteins, the hydrophobins (HFBs) purified from the fungus Pleurotus ostreatus. The protein-modified silicon surface shows an improvement in wettability and is suitable for immobilization of other proteins. Two different proteins were successfully immobilized on the HFBs-coated chips: the bovine serum albumin and an enzyme, a laccase, which retains its catalytic activity even when bound on the chip. Variable-angle spectroscopic ellipsometry (VASE), water contact angle (WCA), and fluorescence measurements demonstrated that the proposed approach in silicon surface bioactivation is a feasible strategy for the fabrication of a new class of hybrid devices.

Langmuir-Blodgett film of hydrophobin protein from Pleurotus ostreatus at the air-water interface

We present results concerning the formation of Langmuir-Blodgett (LB) films of a class I hydrophobin from Pleurotus ostreatus at the air-water interface, and their structure as Langmuir-Blodgett (LB) films when deposited on silicon substrates. LB films of the hydrophobin were investigated by atomic force microscopy (AFM). We observed that the compressed film at the air-water interface exhibits a molecular depletion even at low surface pressure. In order to estimate the surface molecular concentration, we fit the experimental isotherm with Volmer's equation describing the equation of state for molecular monolayers. We found that about (1)/ 10 of the molecules contribute to the surface film formation. When transferred on silicon substrates, compact and uniform monomolecular layers about 2.5 nm thick, comparable to a typical molecular size, were observed. The monolayers coexist with protein aggregates, under the typical rodlet form with a uniform thickness of about 5.0 nm. The observed rodlets appear to be a hydrophilic bilayer and can then be responsible for the surface molecular depletion.

Probing the inner surface of a capillary with the atomic force microscope

The inner surface of a fused silica capillary for zone electrophoresis was probed by the atomic force microscope (AFM) in the contact mode. Only uncoated surfaces were analyzed, after a simple washing cycle with detergent, NaOH and HCl, and final equilibration in distilled water. Three progressively larger surface areas were probed: 0.5 x 0.5 micron, 2 x 2 microns and 4 x 4 microns. In all cases, it was found that the surface is remarkably smooth, with a median height increasing from 1.3 to 5.6 nm; mean height, from 1.3 to 5.8 nm; root-mean-squared roughness, from 0.35 to 1.5 nm; and average roughness, from 0.28 to 0.67 nm (the lower values referring to the smaller area, the larger to the largest area probed). The lowest "peaks" detected are of the order of 1-2 nm; some scattered peaks as high as 16 nm are occasionally found. It is concluded that the inner surface of a capillary is not a serrate or notchy structure, but is indeed quite smooth. Since the average roughness is comprised within the thickness of the diffuse double layer (> 10 nm) existing on the silica wall as a result of silanol ionization (and, in fact, it is on the average considerably smaller), it is concluded that it cannot possibly influence peak shape and contribute to peak decay in an electrophoretic run.