Conjugated Gold-Porphyrin Monolayers Assembled on Inorganic Surfaces.

Gold nanoparticles show important properties owing to their electronic structures. A limitation of some gold nanoparticles is that they either show surface plasmons or luminescence. The increase in size of the gold nanoparticles, and the appearance of the surface plasmons may result in the disappearance of luminescence. The aim of our study is the nanoscale assembly of Au nanoparticles on a monolayer of porphyrin molecules anchored to functionalized inorganic surfaces. This functional architecture not only exhibits a strong surface plasmon due to the gold nanoparticles, but also a strong luminescence signal from the porphyrin molecules. Finally we observed a long-range order in the Au nanoparticles conjugated to the porphyrin monolayer.

Communication between Discrete Nanostructures Triggered by Fine Tuning of an External Stimulus.

The design of molecular architectures able to transfer mass to each other is a field of extreme importance. In the present study it is shown that two especially designed covalently assembled nanostructures can interchange Cu(2+) ions upon an external OH(-) trigger. The obtained solid interfaces are of interest for signaling, communication, memory storage and optical devices.

The pivotal role of copper(II) in the enantiorecognition of tryptophan and histidine by gold nanoparticles.

Stereoselective amino acid analysis has increasingly moved into the scope of interest of the scientific community. In this work, we report a study on the chiral recognition of D,L-Trp and D,L-His using L -Cys-capped gold nanoparticles (AuNPs) and copper(II) ion. In the L -Cys-capped AuNPs, the thiol group of the amino acid interacts with AuNPs through the formation of Au­S bond, whereas the α-amino and α-carboxyl groups of the surface-confined cysteine can coordinate the copper(II) ion, which in turn, binds the L- or D-amino acid present in solution forming diastereoisomeric complexes. The resulting systems have been characterized by UV­Vis spectra and dynamic light scattering measurements, obtaining different results for L- and D-Trp, as well as for L- and D-His. The knowledge of the solution equilibria of the investigated systems allowed us to accurately calculate in advance the concentrations of the species presentin solution and to optimize the system performances, highlighting the pivotal role of copper(II) ion in the enantiodiscrimination processes.

In Situ Labeling of the Aqueous Compartment of Extracellular Vesicles with Luminescent Gold Nanoclusters.

Extracellular vesicles (EVs) are well-known membrane-limited particles secreted by both healthy and cancerous cells. They are considered as biomarkers for early cancer diagnosis and are involved in many pathologies and physiological pathways. They could serve as diagnostic tools in liquid biopsies, as therapeutics in regenerative medicine, or as drug delivery vehicles. Our aim is here to encapsulate luminescent nanoprobes in the aqueous compartment of human EVs extracted from reproductive fluids. The analysis and labeling of the EVs content with easily detectable luminescent nanoparticles could enable a powerful tool for early diagnosis of specific diseases and also for the design of new therapeutics. In this view, gold nanoclusters (AuNCs) appear as an attractive alternative as nontoxic fluorophore probes because of their luminescence properties, large window of fluorescence lifetimes (1 ns-1 µs), ultrasmall size (<2 nm), good biocompatibility, and specific ability as X-ray photosensitizers. Here, we investigated an attractive method that uses fusogenic liposomes to deliver gold nanoclusters into EVs. This approach guarantees the preservation of the EVs membrane without any breakage, thus maintaining compartmental integrity. Different lipid compositions of liposomes preloaded with AuNCs were selected to interact electrostatically with human EVs and compared in terms of fusion efficiency. The mixture of liposomes and EVs results in membrane mixing as demonstrated by FRET experiments and fusion revealed by flux cytometry and cryo-TEM. The resulting fused EVs exhibit typical fluorescence of the AuNCs together with an increased size in agreement with fusion. Moreover, the fusion events in mixtures of EVs and AuNCs preloaded liposomes were analyzed by using cryo-electron microscopy. Finally, the ratio of released AuNCs during the fusion between the fusogenic liposomes and the EVs was estimated to be less than 20 mol % by Au titration using ICP spectroscopy.

Exploiting thermodynamic data to optimize the enantioseparation of underivatized amino acids in ligand exchange capillary electrophoresis.

Stereoselective amino acid analysis has increasingly moved into the scope of interest of the scientific community. In this work, we report a study on the chiral separation of underivatized D,L-His by ligand exchange capillary electrophoresis (LECE), utilizing accurate ex ante calculations. This has been obtained by the addition to the background electrolytes (BGE) of NaClO(4) which renders the separations "all in solution processes", allowing to accurately calculate in advance the concentrations of the species present in solution and to optimize the system performances. To this aim, the formation of ternary complexes of Cu(2+) ion and L-lysine (L-Lys) or L-ornithine (L-Orn) with L- and D-histidine (His), and histamine (Hm) have been studied by potentiometry and calorimetry at 25 °C and with 0.1 mol dm(-3) (KNO(3)) in aqueous solution. The ternary species [Cu(L)(L-His)H](+) and [Cu(L)(D-His)H](+) (where L = L-Lys or L-Orn) show a slight but still detectable stereoselectivity, and the determination of ΔH° and ΔS° values allowed the understanding of the factors which determine this phenomenon. The stereoselectivity showed by the protonated ternary species has been exploited to chirally separate D,L-His in LECE, by using the binary complexes of copper(II) with L-Lys or L-Orn as background electrolytes added with the appropriate amounts of NaClO(4).

Internalization of Pegylated Er:Y2O3 Nanoparticles inside HCT-116 Cancer Cells: Implications for Imaging and Drug Delivery.

Lanthanide-doped nanoparticles, featuring sharp emission peaks with narrow bandwidth, exhibit high downconversion luminescence intensity, making them highly valuable in the fields of bioimaging and drug delivery. High-crystallinity Y2O3 nanoparticles (NPs) doped with Er3+ ions were functionalized by using a pegylation procedure to confer water solubility and biocompatibility. The NPs were thoroughly characterized using transmission electron microscopy (TEM), inductively coupled plasma mass spectrometry (ICP-MS), and photoluminescence measurements. The pegylated nanoparticles were studied both from a toxicological perspective and to demonstrate their internalization within HCT-116 cancer cells. Cell viability tests allowed for the identification of the "optimal" concentration, which yields a detectable fluorescence signal without being toxic to the cells. The internalization process was investigated using a combined approach involving confocal microscopy and ICP-MS. The obtained data clearly indicate the efficient internalization of NPs into the cells with emission intensity showing a strong correlation with the concentrations of nanoparticles delivered to the cells. Overall, this research contributes significantly to the fields of nanotechnology and biomedical research, with noteworthy implications for imaging and drug delivery applications.

Mass spectrometry detection as an innovative and advantageous tool in ligand exchange capillary electrophoresis.

The copper(II) complex of a modified cyclodextrin, namely 6-mono-deoxy-6-[4-(2-aminoethyl)imidazolyl]-ß-CD (CDmh), previously synthesized and characterized in our laboratory and already used as chiral selector for ligand exchange capillary electrophoresis (LECE) with optical detection, is investigated here in LECE using electrospray-mass spectrometry (ESI-MS) as the detection device. The potential of this hyphenated method is compared with the results previously obtained with optical detection by studying the chiral resolution of tryptophan racemate. Chiral separation conditions compatible with LECE-ESI-MS could be achieved based on the figures of merit obtained by LECE-UV. Interestingly, the values of LOD obtained by LECE-ESI-MS were significantly better than those obtained by LECE-UV and thus, ESI-MS detection seems to open new perspectives in chiral separations by LECE.

Polycyclic aromatic hydrocarbons in Mullus surmuletus from the Catania Gulf (Sicily, Italy): distribution and potential health risks.

Different specimens of Mullus surmuletus from the Catania Gulf (Sicily) were sampled and analysed for the quantification of 16 priority polycyclic aromatic hydrocarbons (PAHs) in order to evaluate the distribution of these pollutants and the potential human health risks associated to the consumption of fish. The determined PAHs concentration values ranged from 0.25 to 6.10 ng/g wet weight and the most abundant PAHs detected were lower molecular weight (LMW) compounds with 2 to 3 rings. Relying on the PAHs concentration values, on the consumption data and on the total toxic equivalent (TEQ), the incremental lifetime cancer risk (ILCR) was assessed and its calculated value (2.97 × 10-7) is far below the "maximum acceptable risk level" (ARL), suggesting a low potential carcinogenic risk on consuming M. surmuletus for local population. Even though the study shows a quite low contamination level in M. surmuletus, intensive monitoring programmes are still highly needed in order to provide a better picture of the PAHs distribution in Catania Gulf and of the human health risk linked to fish consumption.

Fast and Efficient Sun Light Photocatalytic Activity of Au_ZnO Core-Shell Nanoparticles Prepared by a One-Pot Synthesis.

Gold nanostructures absorb visible light and show localized surface plasmon resonance bands in the visible region. Semiconducting ZnO nanostructures are excellent for ultraviolet detection, thanks to their wide band gap, large free exciton binding energy, and high electron mobility. Therefore, the coupling of gold and ZnO nanostructures represents the best-suited way to boost photodetection. With the above perspective, we report on the high photocatalytic activity of some Au_ZnO core-shell nanoparticles (NPs) recently prepared by a one-pot synthesis in which a [zinc citrate]- complex acted as the ZnO precursor, a reducing agent for Au3+, and a capping anion for the obtained Au NPs. The overall nanostructures proved to be Au(111) NPs surrounded by a thin layer of [zinc citrate]- that evolved to Au_ZnO core-shell nanostructures. Worthy of note, with this photocatalyst, sun light efficiently decomposes a standard methylene blue solution according to ISO 10678:2010. We rationalized photodetection, reaction rate, and quantum efficiency.

Preclinical evidence of enhanced analgesic activity of duloxetine complexed with succinyl-ß-cyclodextrin: A comparative study with cyclodextrin complexes.

Chronic pain represents one of the most important public health problems, with a great prevalence of comorbidity with depression and cognitive decline. Antidepressants such as duloxetine, a serotonin-norepinephrine reuptake inhibitor, represent an essential part of the therapeutic strategy for chronic pain management in addition to classical analgesics. Duloxetine is endowed with good efficacy and a good profile of safety and tolerability. Yet, duloxetine is metabolized by the cytochrome P450 system 2D6 and 1A2 (CYP2D6 and CYP1A2) and it exhibits moderate inhibitory activity on CYP2D6, resulting in side effects and metabolic interactions that may occur on a long term therapeutic schedule. Cyclodextrins (CyDs) are used in pharmaceutical applications for numerous purposes, including the improvement of drug bioavailability. In order to evaluate their effects on the activity of duloxetine, we first spectrophotometrically studied the host-guest complexes obtained combining duloxetine and different ß-CyD derivatives (ß-CyD, ß-CyDen-c-(Glu-Glu), and succinyl-ß-CyD) and then performed in vivo and in vitro studies. Among duloxetine/CyDs complexes, succinyl-ß-CyD ameliorated the analgesic activity of duloxetine in the tail flick test and in the formalin test in mice and significantly protected the drug from CYP2D6 metabolism.

Ag-NPs induce apoptosis, mitochondrial damages and MT3/OSGIN2 expression changes in an in vitro model of human dental-pulp-stem-cells-derived neurons.

Silver nanoparticles (Ag-NPs) are one of the most popular nanotechnologies because of their unique antibacterial and antifungal properties. Given their increasing use in a wide range of commercial, biomedical and food products, exposure to Ag-NPs is now a reality in people's lives. However, there is a serious lack of information regarding their potential toxic effects in the central nervous system. In this study, we investigated the biocompatibility of "homemade" Ag-NPs in an in vitro model of human neurons derived from dental pulp mesenchymal stem cells. Our results showed that acute exposure to Ag-NPs cause cytotoxicity, by triggering cell apoptosis, damaging neuronal connections, affecting the mitochondrial activity and changing the mRNA expression level of MT3 and OSGIN2, two genes involved in heavy metals metabolism and cellular growth during oxidative stress conditions. Further studies are needed to understand the molecular mechanisms and the physiological consequences underlying Ag-NPs exposure.

Tyrosine capped silver nanoparticles: A new fluorescent sensor for the quantitative determination of copper(II) and cobalt(II) ions.

Nanoparticles have been increasingly used as sensors for several organic and inorganic analytes. In this work, we report a study on the synthesis of novel highly fluorescent l-Tyr capped silver nanoparticles (AgNPs) and their use for the determination of metal ions. The AgNPs have been characterized by TEM, UV-Vis and Photoluminescence (PL) spectroscopy and dynamic light scattering (DLS) measurements and used for the quantitative determination of Co(II) and Cu(II) ions. In the l-Tyr capped AgNPs, the α-amino and α-carboxyl groups of the surface-confined amino acid can coordinate the entitled metal ions, giving rise to a decrease of the silver surface plasmon absorption, that is linearly correlated with the metal ions concentrations. The addition of Co(II) and Cu(II) solutions to the l-Tyr AgNPs also induces a paramagnetic quenching of the fluorescence in the PL spectra and the related Stern Volmer plots highlight a linear correlation over the whole concentration range for both metal ions, with a more pronounced effect for the copper(II) ion.

Fine tuning the pH triggers the enantiorecognition of underivatized amino acids by silver nanoparticles: a novel approach based on the focused use of solution equilibria.

Stereoselective amino acid analysis is still a challenging task. In this work, we report a study on the chiral recognition of D,L-Trp and D,L-His using L-Cys capped silver nanoparticles (AgNPs) and copper(II) ion. The AgNPs have been characterized by TEM, UV-Vis spectra and dynamic light scattering (DLS) measurements and used for chiral discrimination. In the L-Cys capped AgNPs, the α-amino and α-carboxyl groups of the surface-confined amino acid, besides showing either a negative or a neutral charge as a function of the pH, can coordinate the copper(II) ion, which in turn, binds the L- or D-amino acid present in solution forming diastereoisomeric complexes. The resulting systems have been characterized by UV-Vis spectroscopy, exploiting the zwitterionic nature of the cysteine to obtain enantiodiscrimination by a fine tuning of the pH. The analysis of the UV-Vis data by using a multiwavelength approach allows us to determine the kinetic constants ruling the processes.

Self-assembling, patterning and SPR imaging of a 1,3 alternate bis(dipyridyl)calix[4]arene derivative-Cu2+ complex immobilized on to Au(111) surfaces.

The electrochemically switchable Cu(2+) complex of a 1,3 alternate bis(dipyridyl)calix[4]arene derivative forms self-assembled monolayers on Au(111) surfaces. The receptor is patterned on the surface by using microcontact printing procedures and the resulting surface is imaged via SPR.

Barbituric and thiobarbituric acids: a conformational and spectroscopic study.

A conformational study on Barbituric (BA) and Thiobarbituric (TBA) acids was performed at ab initio MP2/6-31G** level on the neutral, protonated, mono- and di-anionic forms. Acid-base equilibria were studied by comparing the electronic transitions evaluated for the most stable conformations and the experimental spectra at different pH values. The electronic transitions were obtained through the ZINDO approach.

Recent advances in chiral separation of amino acids using capillary electromigration techniques.

This review highlights recent progresses in the chiral recognition and separation of amino acid enantiomers obtained by capillary electromigration techniques, using different chiral selectors and especially cyclodextrins, covering the literature published from January 2010 to March 2014. Sections are dedicated to the use of derivatization reagents and to the possibility to enantioseparate underivatized amino acids by using either ligand exchange capillary electrophoresis (LECE) and capillary electrophoresis (CE) coupled on line with mass spectrometry. A short insight on frontier nanomaterials is also given.

Dynamic light scattering on bioconjugated laser generated gold nanoparticles.

Gold nanoparticles (AuNPs) conjugated to DNA are widely used for biomedical targeting and sensing applications. DNA functionalization is easily reached on laser generated gold nanoparticles because of their unique surface chemistry, not reproducible by other methods. In this context, we present an extensive investigation concerning the attachment of DNA to the surface of laser generated nanoparticles using Dynamic Light Scattering and UV-Vis spectroscopy. The DNA conjugation is highlighted by the increase of the hydrodynamic radius and by the UV-Vis spectra behavior. Our investigation indicates that Dynamic Light Scattering is a suitable analytical tool to evidence, directly and qualitatively, the binding between a DNA molecule and a gold nanoparticle, therefore it is ideal to monitor changes in the conjugation process when experimental conditions are varied.

Optimisation methodology in the chiral and achiral separation in electrokinetic chromatography in the case of a multicomponent sample of dansyl amino acids.

Two different chiral selectors synthesised in our laboratory were used to test the possibility of separation for a sample consisting of ten different enantiomeric pairs of dansyl-derivatives of α-amino acids in electrokinetic chromatography. It was possible to observe all the peaks, though only partly resolved, due to the twenty analytes through an accurate strategy of choice of the experimental conditions. As a part of this strategy, a procedure of identification of the single peaks in the electropherograms called LACI (lastly added component identification) has been developed.

Chiral separation of amino acids derivatised with fluorescein isothiocyanate by single isomer derivatives 3-monodeoxy-3-monoamino-ß- and γ-cyclodextrins: the effect of the cavity size.

Thirteen enantiomeric pairs of α-amino acids derivatised with fluorescein isothiocyanate (FITC-AAs) were separated in capillary electrophoresis (CE) using as chiral selectors the single isomer derivatives (SIDs) 3-monodeoxy-3-monoamino-ß- and γ-cyclodextrins. The chiral separation data obtained by these strictly homologous compounds, show different behaviours, allowing to hypothesise a possible structure of the obtained selector-analyte complexes, as well as highlighting the crucial role of the cavity size and the significant effects on the resolution obtained by small differences in the structural characteristics of these analytes.

Application of charged single isomer derivatives of cyclodextrins in capillary electrophoresis for chiral analysis.

The review focuses on the role of ionic or ionisable single isomer derivatives (SIDs) of cyclodextrins on the separation of chiral analytes in capillary electrophoresis (CE), covering the period since the year 2000. The advantages of using pure compounds are discussed, as well as the ways to optimise the separations in the context of a rational approach to these techniques. Specific attention is paid to the modulation of the selector-analyte interaction. The advantage due to a detailed knowledge of equilibria occurring in solution during the CE run is underlined, particularly in the case of the presence of metal complexes, as occurs in chiral ligand exchange capillary electrophoresis (CLECE).