Sers-based nanosensors for the sensitive detection of reactive oxygen species

The unbalanced production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) has been implicated in the pathogenesis of several human diseases. Indeed, there is great interest in developing methods for measuring quantitatively and selectively the production of ROS/RNS in living cells. Here, we report a simple and sensitive method for the detection of ROS, based on surface-enhanced Raman scattering (SERS) spectroscopy

Targeting natural antioxidant compounds to the brain: a metabolomic assessment

2013/2014A diet rich in fruits and vegetables has been associated with a decreased risk of brain diseases. Some plant-specific compounds occurring in fruits and vegetables, such as flavonoids, have been found to exert neuroprotection, thus decreasing neurological disease risk. The current hypothesis is that neuroprotection is due to the antioxidant properties of flavonoids. The main aims of this PhD thesis were: i) to assess whether some flavonoids are transported from the blood into the brain across the blood-brain barrier, ii) to understand if neuroprotection is mediated by an impact on brain metabolism. The first part of the thesis describes in vivo experiments with cyanidin 3-glucoside (C3G), implementing different metabolomics analyses approaches. Mean Time (MT) parameters are reported as useful indicators of the retention properties of C3G in peripheral tissues. The second part deals with the development and characterisation of a selective and sensitive analytical method, based on Surface-Enhanced Raman Spectroscopy (SERS), enabling the assessment of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in living cells.Una dieta ricca in frutta e verdura è stata associata a un ridotto rischio di malattie neurodegenerative, e alcuni composti antiossidanti presenti in frutta e verdura, come i flavonoidi, sono stati riconosciuti come agenti neuroprotettivi. Gli obiettivi principali dell’attività di ricerca riportata in questa tesi sono stati la valutazione del passaggio dal sangue al cervello, attraverso la barriera emato-encefalica, di alcuni flavonoidi, la comprensione del loro impatto sul metabolismo del cervello e del loro meccanismo d'azione come agenti neuroprotettivi. La prima parte della tesi descrive diversi approcci di analisi metabolomica utilizzati in esperimenti in vivo con cianidina 3-glucoside (C3G). Parametri di tempo medio sono riportati come utili indicatori delle proprietà di ritenzione di C3G nei tessuti periferici. La seconda parte presenta lo sviluppo e la caratterizzazione di un metodo analitico, basato sulla spettroscopia Raman amplificata da superfici (SERS), per la determinazione di specie reattive dell’ossigeno e dell’azoto (ROS/RNS), in cellule viventi.XXVII Ciclo198

On the possibility of low cost, adherent therapeutic drug monitoring in oncology

A frequent quantification of drugs concentrations in plasma of patients subject to chemotherapy is seldom performed, mostly because the standard methods (Gas or Liquid Chromatography coupled with Mass Spectroscopy) are expensive and time consuming. In this paper we report the approach pursued in one of the research units of the EU project RAMAN4CLINICS to tackle the problem of a low cost, time adherent quantification of drugs used for oncological patients using a Surface Enhanced Raman Scattering (SERS) spectroscopy. More specifically, the issues concerning the repeatability of the nanostructured substrates will be presented and some promising results to increase the selectivity of the measures toward specific drugs will be discussed, with examples concerning one cytotoxic agent, Irinotecan and one kinase inhibitor, Sunitinib

Application of Paper-Based Microfluidic Analytical Devices (µPAD) in Forensic and Clinical Toxicology: A Review

The need for providing rapid and, possibly, on-the-spot analytical results in the case of intoxication has prompted researchers to develop rapid, sensitive, and cost-effective methods and analytical devices suitable for use in nonspecialized laboratories and at the point of need (PON). In recent years, the technology of paper-based microfluidic analytical devices (μPADs) has undergone rapid development and now provides a feasible, low-cost alternative to traditional rapid tests for detecting harmful compounds. In fact, μPADs have been developed to detect toxic molecules (arsenic, cyanide, ethanol, and nitrite), drugs, and drugs of abuse (benzodiazepines, cathinones, cocaine, fentanyl, ketamine, MDMA, morphine, synthetic cannabinoids, tetrahydrocannabinol, and xylazine), and also psychoactive substances used for drug-facilitated crimes (flunitrazepam, gamma- hydroxybutyric acid (GHB), ketamine, metamizole, midazolam, and scopolamine). The present report critically evaluates the recent developments in paper-based devices, particularly in detection methods, and how these new analytical tools have been tested in forensic and clinical toxicology, also including future perspectives on their application, such as multisensing paper-based devices, microfluidic paper-based separation, and wearable paper-based sensors

Label-Free Quantification of Anticancer Drug Imatinib in Human Plasma with Surface Enhanced Raman Spectroscopy

Therapeutic drug monitoring (TDM) for anticancer drug imatinib has been suggested as the best way to improve the treatment response and minimize the risk of adverse reactions in chronic myelogenous leukemia (CML) and gastrointestinal stromal tumor (GIST) patients. TDM of oncology treatments with standard analytical methods, such as liquid chromatography-tandem mass spectrometry (LC-MS/ MS) is, however, complex and demanding. This paper proposes a new method for quantitation of imatinib in human plasma, based on surface enhanced raman spectroscopy (SERS) and multivariate calibration using partial least-squares regression (PLSR). The best PLSR model was obtained with three latent variables in the range from 123 to 5000 ng/mL of imatinib, providing a standard error of prediction (SEP) of 510 ng/mL. The method was validated in accordance with international guidelines, through the estimate of figures of merit, such as precision, accuracy, systematic error, analytical sensitivity, limits of detection, and quantitation. Moreover, the feasibility and clinical utility of this approach have also been verified using real plasma samples taken from deidentified patients. The results were in good agreement with a clinically validated LC-MS/MS method. The new SERS method presented in this preliminary work showed simplicity, short analysis time, good sensitivity, and could be considered a promising platform for TDM of imatinib treatment in a point-of-care setting

SERS spectroscopy as a tool for the study of thiopurine drug pharmacokinetics in a model of human B leukemia cells

: The thiopurine drugs are immunomodulatory antimetabolites that are characterized by dose-dependent adverse effects such as myelosuppression and hepatotoxicity, often related to inter-individual differences, involving the activity of important enzymes at the basis of their biotransformation, such as thiopurine S-methyltransferase (TPMT). Surface Enhanced Raman Scattering (SERS) spectroscopy is emerging as a bioanalytical tool and represents a valid alternative in terms of affordable costs, shorter analysis time and easier sample preparation in comparison to the most employed methods for pharmacokinetic analysis of drugs. The aim of this study is to investigate mercaptopurine and thioguanine pharmacokinetics by SERS in cell lysates of a B-lymphoblastoid cell line (NALM-6), that did (TPMT*1) or did not (MOCK) overexpress the wild-type form of TPMT as an in vitro cellular lymphocyte model to discriminate between cells with different levels of TPMT activity on the base of the amount of thioguanosine nucleotides (TGN) metabolites formed. SERS analysis of the cell lysates was carried out using SERS substrates constituted by Ag nanoparticles deposited on paper and parallel samples were used for quantification of thiopurine nucleotides with liquid chromatography-tandem mass-spectrometry (LC-MS/MS). A direct SERS detection method has been set up that could be a tool to study thiopurine drug pharmacokinetics in in vitro cellular models to qualitatively discriminate between cells that do and do not overexpress the TPMT enzyme, as an alternative to other more laborious techniques. Results underlined decreased levels of TGN and increased levels of methylated metabolites when TPMT was over expressed, both after mercaptopurine and thioguanine treatments. A strong positive correlation (Spearman's rank correlation coefficient rho = 0.96) exists between absolute quantification of TGMP (pmol/1x106 cells), obtained by LC-MS/MS, and SERS signal (intensity of TGN at 915 cm-1). In future studies, we aim to apply this method to investigate TPMT activity in patients' leukocytes

Long-term stability of an injection-molded zirconia bone-level implant: A testing protocol considering aging kinetics and dynamic fatigue

Abstract Objective Separately addressing the fatigue resistance (ISO 14801, evaluation of final product) and aging behavior (ISO 13356, standardized sample) of oral implants made from yttria-stabilized zirconia proved to be insufficient in verifying their long-term stability, since (1) implant processing is known to significantly influence transformation kinetics and (2) aging, up from a certain level, is liable to decrease fatigue resistance. Therefore, the aim of this investigation was to apply a new testing protocol considering environmental conditions adequately inducing aging during dynamic fatigue. Methods Zirconia implants were dynamically loaded (107 cycles), hydrothermally aged (85\ub0, 60 days) or subjected to both treatments simultaneously. Subsequent, monoclinic intensity ratios (Xm) were obtained by locally resolved X-ray microdiffraction (\u3bc-XRD2). Transformation propagation was monitored at cross-sections by \u3bc-Raman spectroscopy and scanning electron microscopy (SEM). Finally, implants were statically loaded to fracture. Linear regression models (fracture load) and mixed models (Xm) were used for statistical analyses. Results All treatments resulted in increased fracture load (p 64 0.005), indicating the formation of transformation induced compressive stresses around surface defects during all treatment modalities. However, only hydrothermal and combinational treatment were found to increase Xm (p < 0.001). No change in Xm was observed for solely dynamically loaded samples (p 65 0.524). Depending on the variable observed, a monoclinic layer thickness of 1\u20132 \u3bcm (SEM) or 6\u20138 \u3bcm (Raman spectroscopy) was measured at surfaces exposed to water during treatments. Significance Hydrothermal aging was successfully induced during dynamic fatigue. Therefore, the presented setup might serve as reference protocol for ensuring pre-clinically long-term reliability of zirconia oral implants

Label-free Surface Enhanced Raman Scattering (SERS) on Centrifugal Silver Plasmonic Paper (CSPP): A Novel Methodology for Unprocessed Biofluids Sampling and Analysis

Label-free SERS is a powerful bio-analytical technique in which molecular fingerprinting is combined with localized surface plasmons (LSPs) on metal surfaces to achieve high sensitivity. Silver and gold colloids are among the most common nanostructured substrates used in SERS, but since protein-rich samples such as serum or plasma can hinder the SERS effect due to protein–substrate interactions, they often require a deproteinization step. Moreover, SERS methods based on metal colloids often suffer from a poor reproducibility. Here, we propose a paper-based SERS sampling method in which unprocessed human serum samples are first soaked on paper strips (0.4 × 2 cm2), and then mixed with colloidal silver nanoparticles by centrifugation to obtain a Centrifugal Silver Plasmonic Paper (CSPP). The CSPP methodology has the potential to become a promising tool in bioanalytical SERS applications: it uses common colloidal substrates but without the need for sample deproteinization, while having a good reproducibility both in terms of overall spectral shape (r > 0.96) and absolute intensity (RSD < 10%). Moreover, this methodology allows SERS analysis more than one month after serum collection on the paper strip, facilitating storage and handling of clinical samples (including shipping from clinical sites to labs)

The Role of Surface Enhanced Raman Scattering for Therapeutic Drug Monitoring of Antimicrobial Agents

4siThe rapid quantification of antimicrobial agents is important for therapeutic drug monitoring (TDM), enabling personalized dosing schemes in critically ill patients. Highly sophisticated TDM technology is becoming available, but its implementation in hospitals is still limited. Among the various proposed techniques, surface-enhanced Raman scattering (SERS) stands out as one of the more interesting due to its extremely high sensitivity, rapidity, and fingerprinting capabilities. Here, we present a comprehensive review of various SERS-based novel approaches applied for direct and indirect detection and quantification of antibiotic, antifungal, and antituberculosis drugs in different matrices, particularly focusing on the challenges for successful exploitation of this technique in the development of assays for point-of-care tests.openopenFornasaro S.; Cialla-May D.; Sergo V.; Bonifacio A.Fornasaro, S.; Cialla-May, D.; Sergo, V.; Bonifacio, A

The key role of ergothioneine in surface-enhanced Raman scattering spectra of biofluids

Surface-enhanced Raman scattering (SERS) spectroscopy has lately attracted attention in the field of liquid biopsy as a quick and reasonably inexpensive technology that could dramatically improve clinical diagnosis and prognosis. SERS spectra, in fact, provide information about a collection of metabolites present in the studied biofluid, providing biochemical insight into specific health status. Ergothioneine, an unusual dietary amino acid containing the imidazole-2-thione substructure, is important because it is one of the few metabolites in biofluids that can be detected directly (without recognition elements) by SERS. In the past decade, many studies characterizing biofluids or other biological samples have unknowingly linked this amino acid with crucial metabolic processes, including inflammation, in a variety of disorders. With some exceptions, most studies on serum or plasma reported a higher relative amount of ergothioneine in control samples with respect to those of patients affected by a disease. However, because the SERS spectrum of ergothioneine was only recently reported by this group, most previous investigations mistakenly ascribed what are now recognized as spectral bands of this chemical to other compounds. This presentation will summarize and re-evaluate the knowledge about the role of this compound in the so-called “label-free” SERS spectra of biofluids, in order to better understand the role of this compound in numerous clinical conditions