Multivalent and Multifunctional Calixarenes in Bionanotechnology

The key features of calixarene derivatives as multivalent ligands for biomacromolecules and as multifunctional catalysts are reviewed herein. The ease of functionalization and the possibility to control the regio- and stereochemical disposition of multiple ligating units around a central core allow to obtain ligands with high affinity and selectivity especially for proteins and nucleic acids. The hydrophilic/lipophilic character can also be finely tuned, allowing to obtain monomeric hybrid derivatives or amphiphiles able to self-assemble alone or in co-formulation with lipids to give nanoparticles and liposomes that incorporate calixarenes. The knowledge acquired up to now sheds light on the future applications of calixarenes in bionanotechnology and nanomedicine

Energia gravitazionale in astrofisica

Con il termine energia gravitazionale si fa riferimento all'energia potenziale posseduta da un corpo dotato di massa all'interno di un campo gravitazionale. In questa trattazione presenterò una breve introduzione alla teoria del potenziale rimanendo nella teoria classica di gravitazione Newtoniana: ricaveremo l'equazione di Poisson e in seguito un'espressione per l'energia potenziale. Successivamente dedurremo il teorema del viriale, che fornisce una relazione tra alcune energie in gioco in un sistema all'equilibrio ed è un teorema estremamente importante in astrofisica e trova numerosissime applicazioni. Poi, analizzeremo il caso di singola particella che spiraleggia attorno ad un buco nero, per mostrare che nei Nuclei Galattici Attivi, Quasar e in alcuni classi di stelle binarie collassate l'estrazione dell'energia gravitazionale dal materiale che sta accrescendo su questi oggetti è un meccanismo potentissimo per la produzione di radiazione elettromagnetica ad alte energie. I calcoli ci mostreranno infatti che l'effiecienza di conversione da massa in energia può raggiungere il 40%, mentre, per confronto, l'energia prodotta dalle reazioni di fusioni nucleare, nel caso più efficiente, di idrogeno, è circa del 0:7%. Nella seconda applicazione studieremo il problema dell'instabilità di Jeans, in cui considereremo il caso di una nube molecolare sferica autogravitante il cui collasso porta alla formazione di stelle. Infine, applicheremo il teorema del viriale in astrofisica stellare, e vedremo come è utile per descriverne l'evoluzione ed altre quantità di interesse. I vari casi studiato saranno solo una breve e generale trattazione o introduzione al problema, data l'impossibilità di approfondirne i particolari che esulano dallo scopo di questo lavoro

Dried out but alive: how mosquitoes survive 8 months

How malaria mosquitoes persist during the dry season in the Sahel and rapidly rebound at the onset of rains is unclear. Recently, Faiman and colleagues demonstrated that aestivation, a summer dormancy mechanism, is a major persistence strategy of Anopheles mosquitoes, which could be targeted by vector control

Vitiligo and autoimmune thyroid disorders

Vitiligo represents the most common cause of acquired skin, hair and oral depigmentation, affecting 0.5-1% of the population worldwide. It is clinically characterized by the appearance of disfiguring circumscribed skin macules following melanocyte destruction by autoreactive cytotoxic T lymphocytes. Patients affected by vitiligo usually show a poorer quality of life and are more likely to suffer from depressive symptoms, particularly evident in dark-skinned individuals. Although vitiligo is a non-fatal disease, exposure of affected skin to UV light increases the chance of skin irritation and predisposes to skin cancer. In addition, vitiligo has been associated to other rare systemic disorders due to presence of melanocytes in other body districts, such as in the eyes, auditory, nervous and cardiac tissues, where melanocytes are thought to have roles different from that played in the skin. Several pathogenetic models have been proposed to explain vitiligo onset and progression, but clinical and experimental findings point mainly to the autoimmune hypothesis as the most qualified one. In this context, it is of relevance the strong association of vitiligo with other autoimmune diseases, in particular with autoimmune thyroid disorders, such as Hashimoto thyroiditis and Graves’ disease. In this review, after a brief overview of vitiligo and its pathogenesis, we will describe the clinical association between vitiligo and autoimmune thyroid disorders and discuss the possible underlying molecular mechanism(s)

Biosensing with optical fiber gratings

AbstractOptical fiber gratings (OFGs), especially long-period gratings (LPGs) and etched or tilted fiber Bragg gratings (FBGs), are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI) change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength) as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors), and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms

Lossy mode resonance sensors based on tungsten oxide thin films

Tungsten oxide (WO3) thin-films fabricated on glass slides have been proven to generate lossy mode resonances (LMRs) in the visible region. Obtained devices were characterized in transmission by lateral incidence of light on the edge of glass slides. Resonances at both TE and TM polarizations were analyzed for different thicknesses and in different deposition conditions. Moreover, it was successfully proved that WO3 coated glass slides present a high sensitivity to refractive index, which opens the path to the application of this structure in the domain of optical sensors.This work was supported in part by the Spanish Agencia Estatal de Investigación (AEI) through project PID2019-106231RB-I00 and by Italian Ministry of University and Research (MIUR) through the University Research Project 2017 (prot. RG11715C8213BD81)

Elevated immune gene expression is associated with poor reproductive success of urban blue tits

Urban and forest habitats differ in many aspects that can lead to modifications of the immune system of wild animals. Altered parasite communities, pollution, and artificial light at night in cities have been associated with exacerbated inflammatory responses, with possibly negative fitness consequences, but few data are available from free-living animals. Here, we investigate how urbanization affects major immune pathways and experimentally test potentially contributing factors in blue tits (Cyanistes caeruleus) from an urban and forest site. We first compared breeding adults by quantifying the mRNA transcript levels of proteins associated with anti-bacterial, anti-malarial (TLR4, LY86) and anti-helminthic (Type 2 transcription factor GATA3) immune responses. Adult urban and forest blue tits differed in gene expression, with significantly increased TLR4 and GATA3, but not LY86, in the city. We then experimentally tested whether these differences were environmentally induced by cross-fostering eggs between the sites and measuring mRNA transcripts in nestlings. The populations differed in reduced reproductive success, with a lower fledging success and lower fledgling weight recorded at the urban site. This mirrors the findings of our twin study reporting that the urban site was severely resource limited when compared to the forest. Because of low urban survival, robust gene expression data were only obtained from nestlings reared in the forest. Transcript levels in these nestlings showed no (TLR4, LY86), or weak (GATA3), differences according to their origin from forest or city nests, suggesting little genetic or maternal contribution to nestling immune transcript levels. Lastly, to investigate differences in parasite pressure between urban and forest sites, we measured the prevalence of malaria in adult and nestling blood. Prevalence was invariably high across environments and not associated with the transcript levels of the studied immune genes. Our results support the hypothesis that inflammatory pathways are activated in an urban environment and suggest that these differences are most likely induced by environmental factors