Caratterizzazione spettroscopica comparata di campioni di papiro risalenti al VII-IX secolo d.C. e di strisce ricavate da una pianta moderna di papiro

Noninvasive spectroscopic techniques were used in order to characterize papyrus fragments discovered in Egypt, dated to the VII-IX century AD and now preserved at the National library of Vienna. Both the cellulose support and the materials present on the surface of the specimens were studied and identified without affecting the precious artifacts. Fourier transform infrared was employed to characterize the papyrus specimens. The analytical results obtained from the spectroscopic analysis was extremely useful for delineating compositional characteristics both distinctive linked to degradation processes and the different methods of carrying out artifacts and restoration operations incurred in the course of time

Sub-nanomolar detection of biogenic amines by SERS effect induced by hairy Janus silver nanoparticles

Surface enhanced Raman scattering (SERS) is largely used as a transduction method for analytes detection in liquid and vapor phase. In particular, SERS effect was promoted by a plethora of different metal and semiconducting nanoparticles (NPs) and silver and gold nanoparticles appear particularly suitable for this application. Nevertheless, silver nanoparticles intrinsic propensity to aggregate in large clusters reduces the possibility to use naked nanoparticles in SERS applications, for this reason they are usually functionalized with organic molecules. This approach inhibits the aggregation process but, on the other hand, reduces the surficial area of the NPs able to interact with the analyte molecules. In the present work, we propose a simple method to obtain surficial anisotropic Janus silver nanoparticles: octadecylamine was used to stabilize the nanoparticles and to promote the deposition of the silver nanoparticles on a solid substrate. The AgNPs/octadecylamine nanostructures showed the typical “hairy” Janus morphology and a strong SERS effect was observed when two biogenic amines, i. e. 2-phenylethylamine and tyramine, were fluxed on the solid film. SERS phenomenon was studied as a function both of the chemical structure of the fluxed amine and of the distance between the aromatic moiety and the nanoparticle allowing to propose the AgNPs/octadecylamine Janus nanoparticles as an active layer for the detection of phenylethylamine and tyramine in picomolar concentration

Photoresponsive multilayer films by assembling cationic amphiphilic cyclodextrins and anionic porphyrins at the air/water interface

Densely packed hybrid monolayers of amphiphilic cyclodextrins incorporating hydrophilic porphyrins are formed at the air/water interface through electrostatic interaction and can be transferred onto quartz substrates by Langmuir–Scha¨fer deposition. The resulting multilayers exhibit a good response to light excitation as proven by fluorescence emission, triplet– triplet absorption and singlet oxygen photogeneration

Supramolecular organic???inorganic domains integrating fullerene-based acceptors with polyoxometalate-bis-pyrene tweezers for organic photovoltaic applications

A strategy to improve organic photovoltaics, and to enhance the device efficiency, builds on the design of interfacial layered (IFL) materials implementing the performance of the photoactive acceptor/donor system. A novel IFL blend has been engineered by a supramolecular organic-inorganic heterojunction integrating polyoxometalate-bis-pyrene (pyrPOM) receptors that can selectively bind fullerene-based acceptors through π-π interactions and in particular the most used phenyl-C61-butyric acid methyl ester (PCBM) PCBM. The resulting pyrPOM@PCBM IFL, assembled by means of the Langmuir-Blodgett approach, has been fully characterized both in solution and on solid supports by means of the Langmuir-Schaefer method, featuring a high dielectric function, good polarizability and piezo-responsive behavior, which suggest ferroelectric properties. An organic solar cell is realized interposing the IFL between poly(3-hexylthiophene) (P3HT) as polymer donor and the PCBM acceptor layers, thus enhancing the open circuit voltage of the solar device by about 34% under an applied bias of ±5 V. © 2021 The Royal Society of Chemistry

Biocompatible Collagen Paramagnetic Scaffold for Controlled Drug Release

A porous collagen-based hydrogel scaffold was prepared in the presence of iron oxide nanoparticles (NPs) and was characterized by means of infrared spectroscopy and scanning electron microscopy. The hybrid scaffold was then loaded with fluorescein sodium salt as a model compound. The release of the hydrosoluble species was triggered and accurately controlled by the application of an external magnetic field, as monitored by fluorescence spectroscopy. The biocompatibility of the proposed matrix was also tested by the MTT assay performed on 3T3 cells. Cell viability was only slightly reduced when the cells were incubated in the presence of the collagen-NP hydrogel, compared to controls. The economicity of the chemical protocol used to obtain the paramagnetic scaffolds as well as their biocompatibility and the safety of the external trigger needed to induce the drug release suggest the proposed collagen paramagnetic matrices for a number of applications including tissue engeneering and drug delivery

Agent Based Models of Competition and Collaboration

Swarm intelligence is a popular paradigm for algorithm design. Frequently drawing inspiration from natural systems, it assigns simple rules to a set of agents with the aim that, through local interactions, they collectively solve some global problem. Current variants of a popular swarm based optimization algorithm, particle swarm optimization (PSO), are investigated with a focus on premature convergence. A novel variant, dispersive PSO, is proposed to address this problem and is shown to lead to increased robustness and performance compared to current PSO algorithms. A nature inspired decentralised multi-agent algorithm is proposed to solve a constrained problem of distributed task allocation. Agents must collect and process the mail batches, without global knowledge of their environment or communication between agents. New rules for specialisation are proposed and are shown to exhibit improved eciency and exibility compared to existing ones. These new rules are compared with a market based approach to agent control. The eciency (average number of tasks performed), the exibility (ability to react to changes in the environment), and the sensitivity to load (ability to cope with differing demands) are investigated in both static and dynamic environments. A hybrid algorithm combining both approaches, is shown to exhibit improved eciency and robustness. Evolutionary algorithms are employed, both to optimize parameters and to allow the various rules to evolve and compete. We also observe extinction and speciation. In order to interpret algorithm performance we analyse the causes of eciency loss, derive theoretical upper bounds for the eciency, as well as a complete theoretical description of a non-trivial case, and compare these with the experimental results. Motivated by this work we introduce agent "memory" (the possibility for agents to develop preferences for certain cities) and show that not only does it lead to emergent cooperation between agents, but also to a signicant increase in efficiency.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Chirality induction to porphyrin derivatives co-confined at the air–water interface with silica nano-helices: towards enantioselective thin solid film surfaces

A supramolecular approach based on self-assembled structures allows the formation of large structured co-assemblies based on chiral and achiral compounds with original physicochemical features. In this contribution, an achiral and hydrophobic porphyrin was co-assembled at the air-water interface with mesoscopic silica nano-helices dispersed in the water subphase of a Langmuir trough without covalent bond formation. This procedure allowed transferring the porphyrin/nano-helix co-assemblies on a solid support within a thin hybrid layer. The interaction between the two species was characterized using spectroscopic techniques and atomic force microscopy. As evidenced by the circular dichroism measurements performed directly on solid films, tunable chirality was induced to the porphyrin aggregates according to the chirality of the silica nano-helices. When the co-assemblies were transferred on surface plasmon resonance (SPR) slides and exposed to aqueous solutions of histidine enantiomers, selective chiral discrimination was observed which was determined by the matching/mismatching between the chirality of the analyte and the helicity of the nano-helical structure.An achiral hydrophobic porphyrin was assembled onto water suspended silica helices in a Langmuir trough, inducing tunable chirality in the aggregates. Chiral discrimination was observed, ruled by the analyte's chirality and the helices' helicity

MagnetoPlasmonic Waves/HOMO-LUMO Free π-Electron Transitions Coupling in Organic Macrocycles and Their Effect in Sensing Applications

Optical and magneto-optical surface plasmon resonance (MOSPR) characterization and preliminary sensing test onto single- and multi-layers of two organic macrocycles have been performed; TbPc2(OC11H21)8 phthalocyanine and CoCoPo2 porphyrin were deposited by the Langmuir-Schäfer (LS) technique onto proper Au/Co/Au magneto-optical transducers. Investigations of the MOSPR properties in Kretschmann configuration by angular modulation, gives us an indication about the potential discrimination of two organic macrocycles with absorption electronic transition in and out of the propagating plasmon energy spectral range. An improved molecular vapors sensitivity increase by the MOSPR sensing probe can be demonstrated depending on the overlap between the plasmonic probe energy and the absorption electronic transitions of the macrocycles under investigation. If the interaction between the plasmon energy and molecular HOMO-LUMO transition is preserved, a variation in the complex refractive index takes place. Under this condition, the magneto-plasmonic effect reported as 1/|MOSPR| signal allows us to increase the detection of molecules deposited onto the plasmonic transducer and their gas sensing capacity. The detection mechanism appears strongly enhanced if the Plasmon Wave/HOMO-LUMO transitions energy are in resonance. Under coupling conditions, a different volatile organic compounds (VOC) sensing capability has been demonstrated using n-butylamine as the trial molecule

Chiral recognition by supramolecular porphyrin-hemicucurbit[8]uril-functionalized gravimetric sensors

Enantiorecognition of a chiral analyte usually requiresthe abilityto respond with high specificity to one of the two enantiomers ofa chiral compound. However, in most cases, chiral sensors have chemicalsensitivity toward both enantiomers, showing differences only in theintensity of responses. Furthermore, specific chiral receptors areobtained with high synthetic efforts and have limited structural versatility.These facts hinder the implementation of chiral sensors in many potentialapplications. Here, we utilize the presence of both enantiomers ofeach receptor to introduce a novel normalization that allows the enantio-recognitionof compounds even when single sensors are not specific for one enantiomerof a target analyte. For this purpose, a novel protocol that permitsthe fabrication of a large set of enantiomeric receptor pairs withlow synthetic efforts by combining metalloporphyrins with (R,R)- and (S,S)-cyclohexanohemicucurbit[8]uril is developed. The potentialitiesof this approach are investigated by an array of four pairs of enantiomericsensors fabricated using quartz microbalances since gravimetric sensorsare intrinsically non-selective toward the mechanism of interactionof analytes and receptors. Albeit the weak enantioselectivity of singlesensors toward limonene and 1-phenylethylamine, the normalizationallows the correct identification of these enantiomers in the vaporphase indifferent to their concentration. Remarkably, the achiralmetalloporphyrin choice influences the enantioselective properties,opening the way to easily obtain a large library of chiral receptorsthat can be implemented in actual sensor arrays. These enantioselectiveelectronic noses and tongues may have a potential striking impactin many medical, agrochemical, and environmental fields

Supramolecular amplification of amyloid self-assembly by iodination

Amyloid supramolecular assemblies have found widespread exploitation as ordered nanomaterials in a range of applications from materials science to biotechnology. New strategies are, however, required for understanding and promoting mature fibril formation from simple monomer motifs through easy and scalable processes. Noncovalent interactions are key to forming and holding the amyloid structure together. On the other hand, the halogen bond has never been used purposefully to achieve control over amyloid self-assembly. Here we show that single atom replacement of hydrogen with iodine, a halogen-bond donor, in the human calcitonin-derived amyloidogenic fragment DFNKF results in a super-gelator peptide, which forms a strong and shape-persistent hydrogel at 30-fold lower concentration than the wild-type pentapeptide. This is remarkable for such a modest perturbation in structure. Iodination of aromatic amino acids may thus develop as a general strategy for the design of new hydrogels from unprotected peptides and without using organic solvents