Feasibility of SERS-Active Porous Ag Substrates for the Effective Detection of Pyrene in Water

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants that are typically released into the environment during the incomplete combustion of fossil fuels. Due to their relevant carcinogenicity, mutagenicity, and teratogenicity, it is urgent to develop sensitive and cost-effective strategies for monitoring them, especially in aqueous environments. Surface-enhanced Raman spectroscopy (SERS) can potentially be used as a reliable approach for this purpose, as it constitutes a valid alternative to traditional techniques, such as liquid and gas chromatography. Nevertheless, the development of an SERS-based platform for detection PAHs has so far been hindered by the poor adsorption of PAHs onto silver-and gold-based SERS-active substrates. To overcome this limitation, several research efforts have been directed towards the development of functionalized SERS substrates for the improvement of PAH adsorption. However, these strategies suffer from the interference that functionalizing molecules can produce in SERS detection. Herein, we demonstrate the feasibility of label-free detection of pyrene by using a highly porous 3D-SERS substrate produced by an inductively coupled plasma (ICP). Thanks to the coral-like nanopattern exhibited by our substrate, clear signals ascribable to pyrene molecules can be observed with a limit of detection of 23 nM. The observed performance can be attributed to the nanoporous character of our substrate, which combines a high density of hotspots and a certain capability of trapping molecules and favoring their adhesion to the Ag nanopattern. The obtained results demonstrate the potential of our substrates as a large-area, label-free SERS-based platform for chemical sensing and environmental control applications

A simple and reliable approach for the fabrication of nanoporous silver patterns for surface-enhanced Raman spectroscopy applications

The fabrication of plasmonic nanostructures with a reliable, low cost and easy approach has become a crucial and urgent challenge in many fields, including surface-enhanced Raman spectroscopy (SERS) based applications. In this frame, nanoporous metal films are quite attractive, due to their intrinsic large surface area and high density of metal nanogaps, acting as hot-spots for Raman signal enhancement. In this paper, we report a detailed study on the fabrication of nanoporous silver-based SERS substrates, obtained by the application of two successive treatments with an Inductively Coupled Plasma (ICP) system, using synthetic air and Ar as feeding gases. The obtained substrates exhibit a quite broad plasmonic response, covering the Vis–NIR range, and an enhancement factor reaching 6.5 ×107, estimated by using 4-mercaptobenzoic acid (4-MBA) as probe molecule at 532 nm. Moreover, the substrates exhibit a quite good spatial reproducibility on a centimeter scale, which assures a good signal stability for analytical measurements. Globally, the developed protocol is easy and cost effective, potentially usable also for mass production thanks to the remarkable inter-batches reproducibility. As such, it holds promise for its use in SERS-based sensing platforms for sensitive detection of targets molecules

Nanoporous silver films produced by solid-state dewetting for SERS applications

Detection of analytes in aqueous solution with high specificity and sensitivity is of paramount importance in many fields of science, ranging from biomedicine, environmental control, and food quality assessment. Surface-enhanced Raman scattering (SERS) has proven to be a cutting-edge analytical technique for this purpose, by combining the high selectivity of Raman features with the high sensitivity deriving from the plasmonic amplification of Raman signals. Herein, we report a facile and quite effective approach to fabricate large-area Ag-based SERS substrates, exhibiting a porous, coral-like nanotexture. Due to their intrinsic large surface-area and high hot-spot density, the produced substrates appear quite promising for the detection of analytes at trace levels. The nanoporous substrates are produced by Solid-State Dewetting (SSD) of thin Ag-films. In particular, ~30 nm thickness Ag-films are first deposited on glass coverslips by magnetron sputtering. Then, marked roughening is induced by exposing the films to an Inductively Coupled Plasma (ICP) discharge, using synthetic air as feeding gas. The performances of our SERS substrates are characterized in terms of morphology and enhancement factor using CV as probe molecule

Isolation of a 25-kDa protein binding to a curved DNA upstream the origin of the L strand replication in the rat mitochondrial genome

The presence of a curved DNA sequence in the gene for the NADH-dehydrogenase subunit 2 of rat mitochondrial genome, upstream from the origin of the light strand replication have been demonstrated through theoretical analysis and experimental approaches. Gel retardation assays showed that this structure makes a complex with a protein component extracted from the mitochondrial matrix. The isolation and purification of this protein is reported. With a Sepharose CL-6B and magnetic DNA affinity chromatography a polypeptide was purified to homogeneity having 25-kDa mass as shown by gel electrophoresis. To functionally characterize this protein, its capability to bind to other sequences of the homologous or heterologous DNA and to specific riboprobes was also investigated. A role for this protein as a trans-acting agent required for the expression of the mammalian mitochondrial genome is suggested

Single-Cell Photothermal Analysis Induced by MoS2 Nanoparticles by Raman Spectroscopy

Two-dimensional nanomaterials, such as MoS2 nanosheets, have been attracting increasing attention in cancer diagnosis and treatment, thanks to their peculiar physical and chemical properties. Although the mechanisms which regulate the interaction between these nanomaterials and cells are not yet completely understood, many studies have proved their efficient use in the photothermal treatment of cancer, and the response to MoS2 nanosheets at the single-cell level is less investigated. Clearly, this information can help in shedding light on the subtle cellular mechanisms ruling the interaction of this 2D material with cells and, eventually, to its cytotoxicity. In this study, we use confocal micro-Raman spectroscopy to reconstruct the thermal map of single cells targeted with MoS2 under continuous laser irradiation. The experiment is performed by analyzing the water O-H stretching band around 3,400 cm−1 whose tetrahedral structure is sensitive to the molecular environment and temperature. Compared to fluorescence-based approaches, this Raman-based strategy for temperature measurement does not suffer fluorophore instability, which can be significant under continuous laser irradiation. We demonstrate that irradiation of human breast cancer MCF7 cells targeted with MoS2 nanosheets causes a relevant photothermal effect, which is particularly high in the presence of MoS2 nanosheet aggregates. Laser-induced heating is strongly localized near such particles which, in turn, tend to accumulate near the cytoplasmic membrane. Globally, our experimental outcomes are expected to be important for tuning the nanosheet fabrication process

MR Imaging in Sudden Sensorineural Hearing Loss. Time to Talk

SUMMARY: Sudden sensorineural hearing loss is defined as acute hearing loss of the sensorineural type of at least 30 dB over 3 contiguous frequencies that occurs within a 72-hour period. Although many different causative factors have been proposed, sudden sensorineural hearing loss is still considered "idiopathic" in 71%–85% of cases, and treatments are empiric, not based on etiology. MR imaging implemented with a 3D FLAIR sequence has provided new insights into the etiology of sudden sensorineural hearing loss. Herein, we review the current management trends for patients with sudden sensorineural hearing loss, from the initial clinical diagnosis to therapeutic strategies and diagnostic work-up. We focused primarily on MR imaging assessment and discuss the relevance that MR imaging findings might have for patient management, pointing out different perspectives for future clinical research

Comparative analysis of density histograms and visual scores in incremental and volumetric high-resolution computed tomography of the chest in idiopathic pulmonary fibrosis patients

Background: Volumetric high-resolution computed tomography (HRCT) of the chest has recently replaced incremental CT in the diagnostic workup of idiopathic pulmonary fibrosis (IPF). Concomitantly, visual and quantitative scores have been proposed for disease extent assessment to ameliorate disease management. Purpose: To compare the performance of density histograms (mean lung attenuation, skewness, and kurtosis) and visual scores, along with lung function correlations, in IPF patients submitted to incremental or volumetric thorax HRCT. Material and methods: Clinical data and CT scans of 89 newly diagnosed and therapy-naive IPF patients were retrospectively evaluated. Results: Forty-six incremental and 43 volumetric CT scans were reviewed. No differences of density histograms and visual scores estimates were found by comparing two HRCT techniques, with an optimal inter-operator agreement (concordance correlation coefficient >0.90 in all instances). Single-breath diffusing lung capacity for carbon monoxide (DLCOsb) was inversely related with the Best score (r = −00.416; p = 0.014), the Kazerooni fibrosis extent (r = −0.481; p = 0.004) and the mean lung attenuation (r = −0.382; p = 0.026), while a positive correlation was observed with skewness (r = 0.583; p = 0.001) and kurtosis (r = 0.543; p = 0.001) in the incremental HRCT sub-group. Similarly, in the volumetric CT sub-cohort, DLCOsb was significantly associated with skewness (r = 0.581; p = 0.007) and kurtosis (r = 0.549; p = 0.018). Correlations with visual scores were not confirmed. Forced vital capacity significantly related to all density indices independently on HRCT technique. Conclusions: Density histograms and visual scores similarly perform in incremental and volumetric HRCT. Density quantification displays an optimal reproducibility and proves to be superior to visual scoring as more strongly correlated with lung function

SIRT1 activity in peripheral blood mononuclear cells correlates with altered lung function in patients with chronic obstructive pulmonary disease

Background. Oxidative stress is a recognized pathogenic mechanism in chronic obstructive pulmonary disease (COPD). Expression of the NAD+-dependent deacetylase Sirtuin 1 (SIRT1), an antiaging molecule with a key role in oxidative stress response, has been described as decreased in the lung of COPD patients. No studies so far investigated whether systemic SIRT1 activity was associated to decreased lung function in this disease. Methods. We measured SIRT1 protein expression and activity in peripheral blood mononuclear cells (PBMCs) and total oxidative status (TOS), total antioxidant capacity (TEAC), and oxidative stress index (TOS/TEAC) in the plasma of 25 COPD patients, 20 healthy nonsmokers (HnS), and 20 healthy smokers (HS). Results. The activity of SIRT1 was significantly lower in COPD patients compared to both control groups while protein expression decreased progressively (HnS > HS > COPD). TOS levels were significantly lower in HnS than in smoke-associated subjects (COPD and HS), while TEAC levels were progressively lower according (HnS > HS > COPD). In COPD patients, SIRT1 activity, but not protein levels, correlated significantly with both lung function parameters (FEV1/FVC and FEV1) and TEAC. Conclusions. These findings suggest loss of SIRT1-driven antioxidant activity as relevant in COPD pathogenesis and identify SIRT1 activity as a potential convenient biomarker for identification of mild/moderate, stable COPD

Outcomes of interventional sialendoscopy for obstructive salivary gland disorders: an Italian multicentre study

Sebbene le tecniche scialoendoscopiche abbiano assunto un ruolo fondamentale nel trattamento delle patologie ostruttive dei dotti salivari, in letteratura sono riportati pochi studi multicentrici sullargomento. Questo studio basato sullesperienza di 9 centri italiani è stato condotto su 1152 pazienti (553 donne, età media di 50 anni) per un totale di 1342 procedure scialoendoscopiche, il 44,6% delle quali a carico della ghiandola parotide. Il 12% dei pazienti è stato sottoposto a più interventi. I calcoli salivari sono risultati essere la principale causa di ostruzione (55%), seguiti dalle stenosi e altre malformazioni duttali (16%), dai tappi mucosi (14,5%) e dalla scialodochite (4,7%). La procedura endoscopica è stata portata a termine in 1309 casi mentre in 33 casi è stata interrotta, principalmente a causa della presenza di stenosi duttali complete (21 casi). Dopo una o più procedure il successo terapeutico è stato ottenuto nel 92,5% dei pazienti. Complicanze peri-operatorie e post-operatorie sono state riscontrate nel 5,4% dei casi trattati. La scialoendoscopia rappresenta quindi una procedura efficace e sicura nella diagnosi e nel trattamento delle principali patologie ostruttive dei dotti salivari