Non-invasive Spectroscopic Techniques Research Articles

Surface-enhanced FAST CARS: en route to quantum nano-biophotonics

AbstractQuantum nano-biophotonics as the science of nanoscale light-matter interactions in biological systems requires developing new spectroscopic tools for addressing the challenges of detecting and disentangling weak congested optical signals. Nanoscale bio-imaging addresses the challenge of the detection of weak resonant signals from a few target biomolecules in the presence of the nonresonant background from many undesired molecules. In addition, the imaging must be performed rapidly to capture the dynamics of biological processes in living cells and tissues. Label-free non-invasive spectroscopic techniques are required to minimize the external perturbation effects on biological systems. Various approaches were developed to satisfy these requirements by increasing the selectivity and sensitivity of biomolecular detection. Coherent anti-Stokes Raman scattering (CARS) and surface-enhanced Raman scattering (SERS) spectroscopies provide many orders of magnitude enhancement of chemically specific Raman signals. Femtosecond adaptive spectroscopic techniques for CARS (FAST CARS) were developed to suppress the nonresonant background and optimize the efficiency of the coherent optical signals. This perspective focuses on the application of these techniques to nanoscale bio-imaging, discussing their advantages and limitations as well as the promising opportunities and challenges of the combined coherence and surface enhancements in surface-enhanced coherent anti-Stokes Raman scattering (SECARS) and tip-enhanced coherent anti-Stokes Raman scattering (TECARS) and the corresponding surface-enhanced FAST CARS techniques. Laser pulse shaping of near-field excitations plays an important role in achieving these goals and increasing the signal enhancement.

Non-invasive spectroscopic techniques in the diagnosis of non-melanoma skin cancer

The number of non-melanoma skin cancers is increasing worldwide and has become an important health and economic issue. Early detection and treatment of skin cancer can significantly improve patient outcome. Therefore there is an increase in the demand for proper management and effective non-invasive diagnostic modalities in order to avoid relapses or unnecessary treatments. Although the gold standard of diagnosis for non-melanoma skin cancers is biopsy followed by histopathology evaluation, optical non-invasive diagnostic tools have obtained increased attention. Emerging non-invasive or minimal invasive techniques with possible application in the diagnosis of non-melanoma skin cancers include high-definition optical coherence tomography, fluorescence spectroscopy, oblique incidence diffuse reflectance spectrometry among others spectroscopic techniques. Our findings establish how those spectrometric techniques can be used to more rapidly and easily diagnose skin cancer in an accurate and automated manner in the clinic.

Complex structure of the carbon arc discharge for synthesis of nanotubes

Comprehensive non-invasive spectroscopic techniques and electrical measurements of the carbon arc revealed two distinguishable plasma synthesis regions in the radial direction normal to the arc axis. These regions, which are defined as the arc core and the arc periphery, are shown to have very different compositions of carbon species with different densities and temperatures. The colder arc periphery is dominated by carbon diatomic molecules (C2), which are in the minority in the composition of the hot arc core. These differences are due to a highly non-uniform distribution of the arc current, which is mainly conducted through the arc core populated with carbon atoms and ions. Therefore, the ablation of the graphite anode is governed by the arc core, while the formation of carbon molecules occurs in the colder arc periphery. This result is consistent with previous predictions that the plasma environment in the arc periphery is suitable for synthesis of carbon nanotubes.

Contemporary artists' spinel pigments: Non-invasive characterization by means of electronic spectroscopy

The identification of artistic materials represents a fundamental step in supporting the conservation of cultural heritage objects. The importance of their appropriate characterization is particularly relevant in modern-contemporary art, since they could be affected by the occurrence of rapid changes in chemical formulation over time. This paper focuses on an investigation of a series of contemporary blue-green commercial acrylic paints constituted of spinel pigments, using non-invasive spectroscopic techniques. The spectroscopic and color measurements obtained make it possible to characterize the acrylic paints under investigation and to compare the results obtained with those reported in the literature and in spectral databases. To be more precise, the proposed UV–vis-NIR reflectance spectroscopic technique was sensitive enough to characterize the acrylic paints according to their d-d ligand field and the charge transfer (CT) electronic transitions involved in the spinel structures. In addition, an overview of this class of inorganic pigments is also given.

On the identification of folium and orchil on illuminated manuscripts

The identification of the two purple dyes folium and orchil has rarely been reported in the analysis of painted artworks, especially when analysing illuminated manuscripts. This is not consistent with the fact that ancient literary sources suggested their use as substitutes for the more expensive Tyrian purple dye. By employing non-invasive spectroscopic techniques, the present work demonstrates that these dyes were actually widely used in the production of ancient manuscripts. By employing UV–visible diffuse reflectance spectrophotometry with optic fibres (FORS) and spectrofluorimetry, the abundant identification of both dyes on medieval manuscripts was performed by comparing the spectra recorded on ancient codices with those obtained on accurate replicas of dyed or painted parchment. Moreover, examples are also reported whereby the considered purple dyes were used in mixtures with other colourants. The overall information obtained here allowed us to define new boundaries for the time range in which orchil and folium dyes were used which is wider than previously thought, and to focus on their particular uses in the decoration of books.

Caratterizzazione spettroscopica comparata di campioni di papiro risalenti al VII-IX secolo d.C. e di strisce ricavate da una pianta moderna di papiro

Noninvasive spectroscopic techniques were used in order to characterize papyrus fragments discovered in Egypt, dated to the VII-IX century AD and now preserved at the National library of Vienna. Both the cellulose support and the materials present on the surface of the specimens were studied and identified without affecting the precious artifacts. Fourier transform infrared was employed to characterize the papyrus specimens. The analytical results obtained from the spectroscopic analysis was extremely useful for delineating compositional characteristics both distinctive linked to degradation processes and the different methods of carrying out artifacts and restoration operations incurred in the course of time.

Human Auditory Cortex Neurochemistry Reflects the Presence and Severity of Tinnitus.

Permanently affecting one in seven adults, tinnitus lacks both widely effective treatments and adequate understanding of its brain mechanisms. Existing animal models represent tinnitus that may not be distinguishable from homeostatic responses to the auditory insults used to induce it. Human studies can be well controlled in this regard but are usually not (with few even matching control subjects for hearing loss) and are limited in scope as a result of relying solely on non-invasive recording techniques. Here, we exploit recent advances in non-invasive spectroscopic techniques to establish, in a human study tightly controlled for hearing loss and hyperacusis, that tinnitus is associated with a significant reduction in auditory cortex GABA concentration, which has implications for understanding and treatment of the condition.

(IJCESEN)

For different purposes in investigation of cultural heritage samples, including ancient coins, it is necessary to use non-destructive and/or almost non-invasive spectroscopic techniques in combination with appropriate statistical methods. In this paper, we want to show some similarities and certain differences in the elemental composition of two bronze coins, produced for use in the same geographical area, but at different historical moments. We choose the experimental method of laser ablation or laser induced breakdown spectroscopy (LIBS) as well as two emission spectroscopy of x-rays, excited using radioactive source, or x-ray tube. Finally, in qualitative and quantitative interpretation of the multitude of data obtained by LIBS experiment, we used two methods of multivariate analysis, as follow: Principal component analysis (PCA) and Partial least squares (PLS) methods.

Non-invasive multitechnique methodology applied to the study of two 14th century canvases by Lorenzo Veneziano

a b s t r a c t This paper presents the results of a multidisciplinary study on two 14th century canvases attributed to Lorenzo Veneziano. In particular, two non-invasive spectroscopic techniques have been employed, imaging spectroscopy (IS) and X-ray Fluorescence (XRF). In order to perform the analysis in situ, the employed instruments were transportable. The purposes of this analytical approach were mainly to corroborate the authorship and to study the painting materials and execution technique of these two canvases. These two artworks are considered precious because they represent two evidences of the early use of the canvas support in this early period in the North of Italy. Since the paintings are in very delicate conditions, the principal objective of the investigations was to gather as much information as possible avoiding invasive analytical procedures. The paper discusses the potentialities and limitations of the integration of a mobile XRF spectrometer with a transportable IS device, developed to study large- sized surfaces. By means of the elemental composition given by XRF and the colourimetric data and reflectance spectra collected by IS, it has been possible to identify different materials (gypsum, azurite. . .) and to achieve a better understanding of the employed painting technique. The data confirm that the two canvases have been produced with painting materials and technique which are in good agreement with those of Lorenzo Veneziano. The obtained results illustrate the suitability of the integration of XRF with IS to solve similar analytical issues when sampling is not possible.

Non-destructive Analyses of 16th Century Printed Book "Osorio" with the Colorful Fore-edge Miniatures

In our study we are trying to illuminate the palette used by the artist who decorated the fore-edge of the Middle Age printed book description of the military campaign of the Spanish king Emanuel Hier- onymus Osorio and try to give a temporal boundary on the moment of their creation. Our experiments show that a pigment palette is a common one for the period between 16th and 19th century. Several pig- ments were identified, like vermilion and minium, white lead and massicot. Further, we identified the ink used for the book cover inscriptions. Three complementary, non-invasive spectroscopic techniques were used: micro-Raman spectroscopy, PIXE spectroscopy and UV-VIS FORS spectroscopy. The challenges which occurred during the study are presented, such as the positioning of the book underneath the micro- scope or even the fiber optic probe holder, the roughness of the fore-edge surface and the thinness of the color layers.(doi: 10.5562/cca2040)

Noninvasive measurements of carotenoids in bovine udder by reflection spectroscopy

For a long time, the antioxidative status in cattle has been discussed as an indicator for stress conditions resulting from disease or exertion. Until now, invasive approaches have been necessary to obtain blood samples or biopsy materials and gain insights into the antioxidative status of cattle. Due to these efforts and the costs of the analyses, serial sampling is feasible in an experimental setting, but not for measurements on a routine basis. The present study focuses on the feasibility of an innovative, noninvasive spectroscopic technique that allows in vivo measurements of carotenoids in the skin by reflection spectroscopy. To this end, in a first trial, repeated measurements of the carotenoid concentration of the udder skin were performed on 25 healthy cattle from different breeds. Carotenoid concentrations showed highly significant differences between individual animals (P<0.001), although they were kept under the same environmental conditions and received the same diet. The carotenoid concentrations in "sensitive" and "robust" cows (evaluated by a temperament test) differed significantly (P<0.005), with higher concentrations observed in robust cows.

Non-invasive methods for characterisation of printed cultural heritage

Abstract The quality of a book reprint depends on several factors, e.g. paper, typesetting, reproduction of illustrations, printing and bookbinding. The quality of the 1958 and 1988 reprints of the fairytale edition from 1944 designed by the Slovenian architect Jože Plecnik was studied using standard and other non-invasive testing methods, e.g. microscopic and spectroscopic techniques, sonic velocity, Young's modulus of elasticity, surface topography and image analysis. The chemical, physical and colorimetric properties of papers and typographic tonal density were analysed. The results showed that the reprints do not correspond to the originals. Some of the differences in the reprints, if compared with the original (e.g. typographic tonal density), could have been easily avoided, while others (e.g. structural and optical properties of paper) remain unavoidable, mainly due to the influence of internal and external factors on the ageing. The ageing process influences paper properties, since optical properties deteriorate in time. It has been concluded that a precise and systematic study of the properties of an old book should be performed before the preparation of a reprint. The results of the research have shown that the applied methods are useful and satisfactory for the characterisation of the paper properties and typography, and can be of use at the analysis of printing ink and illustration reproduction.

Study ofTrypanosoma cruziepimastigote cell death by NMR-visible mobile lipid analysis

Cell death mechanisms in Trypanosoma cruzi have not been disclosed in detail though different conventional techniques have been used in the classification of parasite-cell death type. Nuclear magnetic resonance (NMR) has successfully been used as a tool to evaluate the onset of apoptosis in a number of higher eukaryote-cell models analysing the ratio of CH(2)/CH(3) integration from the visible mobile lipids (VML). Surprisingly, this versatile non-invasive spectroscopy technique has never been employed with this purpose in T. cruzi. In the present study it is shown that under different parasite death-conditions the ratio CH(2)/CH(3) varied drastically. Thus, T. cruzi epimastigotes in apoptotic conditions increase significantly this ratio while in necrotic as well as in autophagic situations the parasites maintain the VML, CH(2)/CH(3) ratio, in normal values. Additionally, other VML markers commonly used in these studies, such as the change in the region of methyl-choline moiety, -N(+)(CH(3))(3), exhibited different particular patterns according to the type of cell death. Our results suggest that the (1)H NMR-VML technique is an adequate tool to discriminate different T. cruzi death pathways.

Comparative stability study of unit-dose repackaged furosemide tablets

The stability of a 40 mg furosemide tablet drug product repackaged in a unit-dose USP class A blister pack and the identical product in its original container made of HDPE material was studied under ICH long-term conditions of 25°C and relative humidity (RH) of 60% and accelerated stressed conditions of 40°C and 75% RH. Samples from original and repackaged drug products were periodically removed from storage conditions and subjected to pharmaceutical and spectroscopic analysis. Results indicate the potency 91.5 ± 0.9% of the tablet strength for the original packaging drug product vs 91.6 ± 4.0% for the repackaged product are statistically similar for long-term and accelerated stress conditions. Tablet hardness (6.0 ± 0.3 KP) and loss on drying (3.2%) was the same for original and repackaged drug products under both stressed conditions indicating similar moisture sorption behavior. Non-invasive spectroscopic techniques did not show any differences in moisture content. Dissolution and TGA results were simil...

Combined non-destructive XRF and SR-XAS study of archaeological artefacts

We report on a non-destructive study of Sicilian ceramic fragments of cultural heritage interest, classified as "proto-majolica" pottery and dating back to the twelfth to thirteen centuries AD. The analytical approach used is based on the employment of two totally non-invasive spectroscopic techniques: X-ray fluorescence (XRF), using a portable energy-dispersive XRF analyser, and X-ray absorption spectroscopy, using synchrotron radiation as a probe (SR-XAS). XRF measurements allowed us to collect elemental and spatially resolved information on major and minor constituents of the decorated coating of archaeological pottery fragments, so providing preliminary results on the main components characterizing the surface. In particular, we assigned to Fe and Mn the role of key elements of the colouring agent. With the aim of obtaining more detailed information, we performed SR-XAS measurements at the Fe and Mn K-edges at the Italian BM08 beamline at the European Synchrotron Radiation Facility (Grenoble, France). The experimental data were analysed by applying principal component analysis and least-squares fitting to the near-edge part of the spectra (X-ray absorption near-edge structure) to determine the samples' speciation. From the overall results, umber, a class of brownish pigments characterized by a mixture of hydrated iron and manganese oxides, has been ascribed as a pigmenting agent.

Detection of minor salivary glands affected in Sjogren’s syndrome by Raman spectroscopy

Sjogren's syndrome(SS) is defined as a slowly processing autoimmune inflammatory exocrinopathy affecting the salivary and lachrymal glands. Due to the difficulty in reaching a diagnosis in some SS cases, there are many criteria published for classification and diagnosis. Among the most of criteria, lip biopsy plays an important role in clinical diagnosis, but it is an invasive and complex method which always causes patients' pain and discomfort. Raman spectroscopy is a noninvasive and real-time vibrational spectroscopic technique applied in the clinical detection and diagnosis of diseases. The diagnostic sensitivity and specificity are both high. The hypothesis is to detect the minor salivary glands affected in SS by the noninvasive Raman spectroscopy instead of lip biopsy. Therefore, Raman spectroscopy may increase the diagnostic sensitivity and specificity, meanwhile prevent patients from pain caused by biopsy.

Optical and X‐ray Fluorescence Spectroscopy Studies of Bone and Teeth in Newborn Rats After Maternal Treatment with Indinavir

An experiment estimating influence of antiviral drug indinavir treatment during pregnancy on bones and teeth development in newborn rats was performed. Two different fluorescence noninvasive spectroscopy techniques, i.e. laser (407 nm)-induced fluorescence method to characterize the organic fluorescent molecules and X-ray fluorescence analysis to determine mineral components were used to study the surface response of femur, mandible and incisor during their formation in the first month of a rat's life. Differences in autofluorescence depending on the form of the bone were observed on the basis of the emission from enamel in 7-, 14- and 28-day-old newborn rats. The dependence between decrease in intensity of fluorescence and increase in mineralization with age in newborn rats was observed. An enhancement of the autofluorescence and a decrease in the concentration of Ca as a main element, as well as disturbances in the concentration of Zn as trace element were observed for bone as well as teeth in newborns during the first month of their life after maternal administration of indinavir (500 mg kg(-1) p.o.) in comparison with the control group. The results indicate that indinavir causes a delay in development of the skeleton and teeth in newborn rats.

Characterisation of foxing stains in eighteenth to nineteenth century drawings using non-destructive techniques

The reddish-brown, brown or yellowish stains of circular or irregular shape known as foxing spots have been fully described in conservation literature but still, this phenomenon does not find any scientific agreement since many hypotheses have been raised concerning their origin. In this work a contribution to foxing definition not only focussed on its appearance but also reported on its chemical information. For this purpose foxing stains present in drawings from two Portuguese artists dated from the eighteenth to nineteenth centuries were observed under ultra-violet light and optical microscope and analysed by three non-invasive spectroscopy techniques. The observations carried out on the stains provided information on their surface morphology. The use of energy-dispersive X-ray fluorescence revealed a variation on the elemental content between foxing and paper region. Although the results from X-ray diffraction analysis showed no signs of cellulose degradation in foxing stains, Fourier-transformed infrared analysis revealed the presence of oxide groups. Both the information on the chemical nature and surface morphology of the stains achieved in this study will contribute to increase foxing formation information and develop future protocols for conservation purposes.

Arterial flow measurements during reactive hyperemia using NIRS

Non-invasive evaluation of peripheral perfusion may be useful in many contexts including clinical research. We validated a novel non-invasive spectroscopy technique to quantify forearm arterial inflow. This method, which is based on the measurement of tissular total hemoglobin variations after an ischemic period, was compared to strain gauge plethysmography (SGP). The technique uses near-infrared spectroscopy (NIRS) to determine the rate of change of forearm tissue oxygenation during reactive hyperemia. In this study, 13 subjects were simultaneously evaluated with NIRS and SGP. Nine baseline flow measurements were performed to assess the reproducibility of each method. Twenty-seven serial measurements were then made to evaluate flow variation during forearm reactive hyperemia. SGP and NIRS methods showed excellent reproducibility with the same intra-class correlation coefficients (0.98). In conclusion, the NIRS technique appears well suited for non-invasive evaluation of quantitative arterial forearm flow.

Neutron Stimulated Emission Computed Tomography for Diagnosis of Breast Cancer

Neutron stimulated emission computed tomography (NSECT) is being developed as a non-invasive spectroscopic imaging technique to determine element concentrations in the human body. NSECT uses a beam of fast neutrons that scatter inelastically from atomic nuclei in tissue, causing them to emit characteristic gamma photons that are detected and identified using an energy-sensitive gamma detector. By measuring the energy and number of emitted gamma photons, the system can determine the elemental composition of the target tissue. Such determination is useful in detecting several disorders in the human body that are characterized by changes in element concentration, such as breast cancer. In this paper we describe our experimental implementation of a prototype NSECT system for the diagnosis of breast cancer and present experimental results from sensitivity studies using this prototype. Results are shown from three sets of samples: (a) excised breast tissue samples with unknown element concentrations, (b) a multi-element calibration sample used for sensitivity studies, and (c) a small-animal specimen, to demonstrate detection ability from in-vivo tissue. Preliminary results show that NSECT has the potential to detect elements in breast tissue. Several elements were identified common to both benign and malignant samples, which were confirmed through neutron activation analysis (NAA). Statistically significant differences were seen for peaks at energies corresponding to 37Cl, 56Fe, 58Ni, 59Co, 79Br and 87Rb. The spectrum from the small animal specimen showed the presence of 12C from tissue, from bone, and elements 39K, 27Al, 37Cl, 56Fe, 68Zn and 25Mg. Threshold sensitivity for the four elements analyzed was found to range from 0.3 grams to 1 gram, which is higher than the microgram sensitivity required for cancer detection. Patient dose levels from NSECT were found to be comparable to those of screening mammography.