Plasmonic nanostructures for optical biosensing

In the last few decades, an increasing interest for nanotechnologies is spanning more and more fields of application thanks to the unique properties exhibited by metal nanomaterials if stimulated by external electromagnetic radiations. Indeed, a new research field called plasmonics is emerging and fast growing as a result of the recent technological progress and a deeper understanding of such phenomena. Recently, several types of plasmonic nanostructures are being conceived aiming at improving the performance of plasmon-based devices. For instance, sharp nanostructures exhibit higher field enhancement than smooth surfaces thereby representing a remarkable advantage in applications relying on signal amplification such as surface-enhanced Raman spectroscopy and plasmon-enhanced fluorescence. In addition, when nanostructures are ordered in periodic arrays, collective modes can arise as a result of the field coupling among the surface plasmons so as to promote the occurrence of impressive effects such as lattice resonances. Therefore, the possibility to tune the optical response of a nanostructure by tailoring the nanomaterial shape and size, as well as the structure arrangement, is spurring the researchers to explore new approaches, in terms of both nanofabrication and nano applications, in order to go beyond the current limits of many techniques. The aim of this work is to provide an understanding of this growing field of research and to convey the main features in biosensing applications. To date, several biosensor-based approaches including colorimetric and fluorescence analysis have been explored to effectively work alongside – or even replace – the gold standard methods in a wide variety of applications including environmental pollution monitoring and medical diagnostics. In this regard, optical biosensors offer a rapid, affordable, and practical approach in many fields of applications paving the way for point of care tests and high-throughput analysis. Fluorescence-based techniques are of growing interest since their potential high-throughput analysis, point of care applications, and improvable sensitivity through plasmon-enhanced fluorescence effect. On the other hand, when quickness, practicality, and easiness of use are preferred rather than extremely high sensitivity and accuracy, colorimetric biosensors relying on gold nanoparticles are the ideal candidates since their capability to produce a qualitative response in a few minutes visible by naked eye (a portable and handheld spectrophotometer can be employed if a quantitative measurement is required). The performance of colorimetric biosensors have been tested for detecting small molecules, such as 17β-estradiol in tap water down to picomolar level, and SARS-CoV-2 virions in naso-oropharyngeal swabs from hospital patients, whereas two-dimensional patterns of honeycomb-arranged and randomly positioned gold nanoparticles have been implemented in fluorescence-based malaria apta-immunoassays to effectively amplify the signal intensity through plasmon-enhanced fluorescence effect thereby attaining an ultrasensitive limit of detection at femtomolar level for detecting proteins in human whole blood

Sviluppo di approcci farmacologici innovativi per la terapia della malattia di Pompe

La malattia di Pompe (PD) è una grave miopatia ereditaria causata da una mutazione nel gene che codifica per l'α-glucosidasi acida GAA, enzima deputato alla scomposizione del glicogeno lisosomiale. I danni più significativi si osservano soprattutto nel muscolo scheletrico e cardiaco, a causa dell'accumulo materiale autofagico, che depositandosi in maniera anomala nei tessuti li danneggia e causa un lento e progressivo indebolimento della muscolatura. Attualmente l'unico approccio farmacologico è rappresentato dalla terapia enzimatica sostitutiva (ERT) che prevede la somministrazione di un enzima umano ricombinante (rh-GAA). La ERT però presenta forti limitazioni, in quanto non tutti i pazienti rispondono ugualmente bene al trattamento e non tutte le manifestazioni cliniche risultano corrette. Non è del tutto chiaro il motivo per cui ciò accade, ma probabilmente diversi fattori concorrono a limitare il successo terapeutico della ERT, tra cui l'età d'inizio del trattamento, lo stato immunologico dei pazienti, il possibile instabilità a pH neutro dell'enzima ricombinante durante il transito verso i lisosomi, la relativa carenza del recettore del mannosio-6-fosfato nelle cellule muscolari. Per tutti questi motivi è fondamentale individuare approcci alternativi e innovativi che possano superare le forti limitazioni che la terapia attualmente in uso per la cura di questa malattia presenta, al fine di migliorare le aspettative e la qualità di vita dei pazienti. Il progetto dal titolo "Sviluppo di approcci farmacologici innovativi per la terapia della malattia di Pompe" è incentrato sulla caratterizzazione di un nuovo enzima umano ricombinante prodotto in riso, geneticamente modificato, e all'individuazione di chaperones farmacologici di nuova generazione, atti a migliorare la stabilità e l'efficacia degli enzimi ricombinanti per la malattia di Pompe

An Illusion of Safety: Why Congress Should Let FISA\u27s Lone Wolf Amendment Expire

FISA’s lone wolf amendment is set to expire on December 15, 2019. Created after 9/11 to address evolving threats, specifically lone wolf terrorists, it expanded the government\u27s ability to obtain FISA surveillance warrants for supposed lone wolves. However, since its enactment, it has apparently never been used in the course of an investigation, despite the significant number of lone wolf attacks. Moreover, it is not clear that the lone wolf amendment was originally needed, or that it has the ability to effectively confront the lone wolf threat. This Note argues that Congress should critically evaluate the lone wolf amendment, use this as an opportunity to exercise its oversight role, and let the lone wolf amendment expire

Temperature and pressure gas geoindicators at the Solfatara fumaroles (Campi Flegrei)

Long time series of fluid pressure and temperature within a hydrothermal system feeding the Solfatara fumaroles are investigated here, on the basis of the chemical equilibria within the CO2–H2O–H2–CO gas system. The Pisciarelli fumarole external to Solfatara crater shows an annual cycle of CO contents that indicates the occurrence of shallow secondary processes that mask the deep signals. In contrast, the Bocca Grande and Bocca Nova fumaroles located inside Solfatara crater do not show evidence of secondary processes, and their compositional variations are linked to the temperature–pressure changes within the hydrothermal system. The agreement between geochemical signals and the ground movements of the area (bradyseismic phenomena) suggests a direct relationship between the pressurization process and the ground uplift. Since 2007, the gas geoindicators have indicated pressurization of the system, which is most probably caused by the arrival of deep gases with high CO2 contents in the shallow parts of the hydrothermal system. This pressurization process causes critical conditions in the hydrothermal system, as highlighted by the increase in the fumarole temperature, the opening of new vents, and the localized seismic activity. If the pressurization process continues with time, it is not possible to rule out the occurrence of phreatic explosions

PDDL+ Planning with Hybrid Automata: Foundations of Translating Must Behavior

Planning in hybrid domains poses a special challenge due to the involved mixed discrete-continuous dynamics. A recent solving approach for such domains is based on applying model checking techniques on a translation of PDDL+ planning problems to hybrid automata. However, the proposed translation is limited because must behavior is only overapproximated, and hence, processes and events are not re- flected exactly. In this paper, we present the theoretical foundation of an exact PDDL+ translation. We propose a schema to convert a hybrid automaton with must transitions into an equivalent hybrid automaton featuring only may transitions

The Fe65 Adaptor Protein Interacts through Its PID1 Domain with the Transcription Factor CP2/LSF/LBP1

The neural protein Fe65 possesses three putative protein-protein interaction domains: one WW domain and two phosphotyrosine interaction/phosphotyrosine binding domains (PID1 and PID2); the most C-terminal of these domains (PID2) interacts in vivo with the Alzheimer's beta-amyloid precursor protein, whereas the WW domain binds to Mena, the mammalian homolog of Drosophila-enabled protein. By the interaction trap procedure, we isolated a cDNA clone encoding a possible ligand of the N-terminal PID/PTB domain of Fe65 (PID1). Sequence analysis of this clone revealed that this ligand corresponded to the previously identified transcription factor CP2/LSF/LBP1. Co-immunoprecipitation experiments demonstrated that the interaction between Fe65 and CP2/LSF/LBP1 also takes place in vivo between the native molecules. The localization of both proteins was studied using fractionated cellular extracts. These experiments demonstrated that the various isoforms of CP2/LSF/LBP1 are differently distributed among subcellular fractions. At least one isoform, derived from alternative splicing (LSF-ID), is present outside the nucleus; Fe65 was found in both fractions. Furthermore, transfection experiments with an HA-tagged CP2/LSF/LBP1 cDNA demonstrated that Fe65 interacts also with the nuclear form of CP2/LSF/LBP1. Considering that the analysis of Fe65 distribution in fractionated cell extracts demonstrated that this protein is present both in nuclear and non-nuclear fractions, we examined the expression of Fe65 deletion mutants in the two fractions. This analysis allowed us to observe that a small region N-terminal to the WW domain is phosphorylated and is necessary for the presence of Fe65 in the nuclear fraction

Long time-series of chemical and isotopic compositions of Vesuvius fumaroles: evidence for deep and shallow processes

Long time-series of chemical and isotopic compositions of Vesuvius fumaroles were acquired in the framework of the volcanic surveillance in the 1998-2010 period. These allow the identification of processes that occur at shallow levels in the hydrothermal system, and variations that are induced by deep changes in volcanic activity. Partial condensation processes of fumarolic water under near-discharge conditions can explain the annual 18O and deuterium variabilities that are observed at Vesuvius fumaroles. Significant variations in the chemical compositions of fumaroles occurred over the 1999-2002 period, which accompanied the seismic crisis of autumn 1999, when Vesuvius was affected by the most energetic earthquakes of its last quiescence period. A continuous increase in the relative concentrations of CO2 and He and a general decrease in the CH4 concentrations are interpreted as the consequence of an increment in the relative amount of magmatic fluids in the hydrothermal system. Gas equilibria support this hypothesis, showing a PCO2 peak that culminated in 2002, increasing from values of ~40 bar in 1998 to ~55-60 bar in 2001- 2002. We propose that the seismic crisis of 1999 marked the arrival of the magmatic fluids into the hydrothermal system, which caused the observed geochemical variations that started in 1999 and culminated in 2002

Temperature and pressure gas geoindicators at the Solfatara fumaroles (Campi Flegrei)

Long time series of fluid pressure and temperature within a hydrothermal system feeding the Solfatara fumaroles are investigated here, on the basis of the chemical equilibria within the CO2-H2O-H2-CO gas system. The Pisciarelli fumarole external to Solfatara crater shows an annual cycle of CO contents that indicates the occurrence of shallow secondary processes that mask the deep signals. In contrast, the Bocca Grande and Bocca Nova fumaroles located inside Solfatara crater do not show evidence of secondary processes, and their compositional variations are linked to the temperature–pressure changes within the hydrothermal system. The agreement between geochemical signals and the ground movements of the area (bradyseismic phenomena) suggests a direct relationship between the pressurization process and the ground uplift. Since 2007, the gas geoindicators have indicated pressurization of the system, which is most probably caused by the arrival of deep gases with high CO2 contents in the shallow parts of the hydrothermal system. This pressurization process causes critical conditions in the hydrothermal system, as highlighted by the increase in the fumarole temperature, the opening of new vents, and the localized seismic activity. If the pressurization process continues with time, it is not possible to rule out the occurrence of phreatic explosions

Analysis of the optical response of a SARS-CoV-2-directed colorimetric immunosensor

The optical response of different configurations of functionalized gold nanoparticles (f-AuNPs) and SARS-CoV-2 virions is simulated in order to explore the behavior of a colloidal solution containing 105–1013 virions/ml. The analysis herein reported is carried out for three concentration regimes: (i) low (≲108 virions/ml), (ii) intermediate (∼109–1010 virions/ml), and (iii) high (≳1011 virions/ml). Given the high binding effectiveness of f-AuNPs to virions, three different configurations are expected to arise: (i) virions completely surrounded by f-AuNPs, (ii) aggregates (dimers or trimers) of virions linked by f-AuNPs, and (iii) single f-AuNP surrounded by virions. It is demonstrated that 20 nm diameter gold nanoparticles functionalized against all three kinds of SARS-CoV-2 proteins (membrane, envelope, and spike) allow one to reach a limit of detection (LOD) of ∼106 virions/ml, whereas the use of only one kind of f-AuNP entails a ten-fold worsening of the LOD. It is also shown that the close proximity (∼5 nm) of the f-AuNP to the virions assumed throughout this analysis is essential to avoid the hook effect, thereby pointing out the importance of realizing an apt functionalization procedure that keeps thin the dielectric layer (e.g., proteins or aptamers) surrounding the gold nanoparticles