Classification of edible and lampante virgin olive oil based on synchronous fluorescence and total luminescence spectroscopy

Total luminescence and synchronous fluorescence spectroscopies were tested as regards their ability to differentiate edible from lampante virgin olive oils. Total luminescence spectra were recorded by measuring the emission spectra in the range 350-720 nm at excitation wavelengths from 320 to 535 nm. The synchronous fluorescence spectra of 41 edible and 32 lampante virgin olive oils were acquired by synchronous scanning the excitation and emission monochromator maintained at an offset value of 80 nm. Classification of virgin olive oils based on their synchronous fluorescence spectra was performed by hierarchical cluster analysis and principal component analysis using the spectral range of 429-545 nm. Principal component analysis provided better discrimination between the two classes, without any classification error, while hierarchical cluster analysis allowed 97.3% correct classification. These results indicate the capability of fluorescence techniques to differentiate virgin olive oils according to their quality.     

DNA and protein changes caused by disease in human breast tissues probed by the Kubelka-Munk spectral functional

Malignant, fibroadenoma, normal and adipose breast tissues were studied using diffuse reflectance spectroscopy. The absorption spectra of the breast tissues were extracted from the diffuse reflectance spectra using the Kubelka-Munk function (K-M function). The spectral features of the K-M function were identified and compared with those of the absorption spectra. The spectral features of the K-M function were assigned to DNA, protein, beta-carotene and hemoglobin (oxygenated and deoxygenated) molecules in the breast tissue. The amplitudes of the K-M function averaged from 275 to 285 nm and from 255 to 265 nm and were found to be different for malignant, fibroadenoma and normal tissues. These differences were attributed to changes in proteins and DNA. A set of critical parameters was determined for separating malignant tissues from fibroadenoma and normal tissues. This approach should hold for other tissue types such as cervix, uterus and colon.     

A pilot study on colonic mucosal tissues by fluorescence spectroscopy technique: Discrimination by principal component analysis (PCA) and artificial neural network (ANN) analysis

Pulsed laser‐induced autofluorescence spectra of pathologically certified normal and malignant colonic mucosal tissues were recorded at 325 nm excitation. The spectra were analysed using three different methods for discrimination purposes. First, all the spectra were subjected to the principal component analysis (PCA) and the discrimination between normal and malignant cases were achieved using parameters like, spectral residuals, Mahalanobis distance and scores of factors. Second, to understand the changes in tissue composition between the two classes (normal, and malignant), difference spectrum was constructed by subtracting mean spectrum of calibration set samples from simulated mean of all spectra of any one class (normal/malignant) and in third, artificial neural network (ANN) analysis was carried out on the same set of spectral data by training the network with spectral features like, mean, median, spectral residual, energy, standard deviation, number of peaks for different thresholds (100, 250 and 500) after carrying out 1st‐order differentiation of the training set samples and discrimination between normal and malignant conditions were achieved. The specificity and sensitivity were determined in PCA and ANN analyses and they were found to be 100 and 91.3% in PCA, and 100 and 93.47% in ANN, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

High-wavenumber FT-Raman spectroscopy for in vivo and ex vivo measurements of breast cancer

The identification of normal and cancer breast tissue of rats was investigated using high-frequency (HF) FT-Raman spectroscopy with a near-infrared excitation source on in vivo and ex vivo measurements. Significant differences in the Raman intensities of prominent Raman bands of lipids and proteins structures (2,800?C3,100?cm^?1) as well as in the broad band of water (3,100?C3,550?cm^?1) were observed in mean normal and cancer tissue spectra. The multivariate statistical analysis methods of principal components analysis (PCA) and linear discriminant analysis (LDA) were performed on all high-frequency Raman spectra of normal and cancer tissues. LDA results with the leave-one-out cross-validation option yielded a discrimination accuracy of 77.2, 83.3, and 100% for in vivo transcutaneous, in vivo skin-removed, and ex vivo biopsy HF Raman spectra. Despite the lower discrimination value for the in vivo transcutaneous measurements, which could be explained by the breathing movement and skin influences, our results showed good accuracy in discriminating between normal and cancer breast tissue samples. To support this, the calculated integration areas from the receiver-operating characteristic (ROC) curve yielded 0.86, 0.94, and 1.0 for in vivo transcutaneous, in vivo skin-removed, and ex vivo biopsy measurements, respectively. The feasibility of using HF Raman spectroscopy as a clinical diagnostic tool for breast cancer detection and monitoring is due to no interfering contribution from the optical fiber in the HF Raman region, the shorter acquisition time due to a more intense signal in the HF Raman region, and the ability to distinguish between normal and cancerous tissues.     

Optimal excitation wavelengths for in vivo detection of oral neoplasia using fluorescence spectroscopy

There is no satisfactory mechanism to detect premalignant lesions in the upper aero-digestive tract. Fluorescence spectroscopy has potential to bridge the gap between clinical examination and invasive biopsy; however, optimal excitation wavelengths have not yet been determined. The goals of this study were to determine optimal excitation-emission wavelength combinations to discriminate normal and precancerous/cancerous tissue, and estimate the performance of algorithms based on fluorescence. Fluorescence excitation-emission matrices (EEM) were measured in vivo from 62 sites in nine normal volunteers and 11 patients with a known or suspected premalignant or malignant oral cavity lesion. Using these data as a training set, algorithms were developed based on combinations of emission spectra at various excitation wavelengths to determine which excitation wavelengths contained the most diagnostic information. A second validation set of fluorescence EEM was measured in vivo from 281 sites in 56 normal volunteers and three patients with a known or suspected premalignant or malignant oral cavity lesion. Algorithms developed in the training set were applied without change to data from the validation set to obtain an unbiased estimate of algorithm performance. Optimal excitation wavelengths for detection of oral neoplasia were 350, 380 and 400 nm. Using only a single emission wavelength of 472 nm, and 350 and 400 nm excitation, algorithm performance in the training set was 90% sensitivity and 88% specificity and in the validation set was 100% sensitivity, 98% specificity. These results suggest that fluorescence spectroscopy can provide a simple, objective tool to improve in vivo identification of oral cavity neoplasia.     

Spectroscopic diagnosis of colonic dysplasia.

We have developed a method for defining diagnostic algorithms for pathologic conditions based on fluorescence spectroscopy. We apply this method to human colon tissue and show that fluorescence can be used to diagnose the presence or absence of colonic adenoma. This method uses fluorescence excitation-emission matrices (EEM) to identify optimal excitation regions for obtaining fluorescence emission spectra which can be used to differentiate normal and pathologic tissues. In the case of normal and adenomatous colon tissue, these were found to be: 330, 370, and 430 nm +/- 10 nm. At these excitation wavelengths, emission wavelengths for use in diagnostic algorithms are identified from average difference and ratio of the spectra from normal and pathologic tissues. In colon tissue, at 370 nm excitation, 404, 480, and 680 nm were found to be useful emission wavelengths for diagnosing the presence of adenoma in vitro. The basis of colon tissue autofluorescence was investigated using EEM of pure molecules and relevant excitation-emission maxima in the literature.     

Using the Method of “Optical Biopsy” of Prostatic Tissue to Diagnose Prostate Cancer

Simple SummaryAnalytical discrimination models of Raman spectra of prostate cancer tissue were constructed by using the projections onto latent structures data analysis (PLS-DA) method for different wavelengths of exciting radiation—532 and 785 nm. These models allowed us to divide the Raman spectra of prostate cancer and the spectra of hyperplasia sites for validation datasets with the accuracy of 70–80%, depending on the specificity value. Meanwhile, for the calibration datasets, the accuracy values reached 100% for the excitation of a laser with a wavelength of 785 nm. Due to the registration of Raman “fingerprints”, the main features of cellular metabolism occurring in the tissue of a malignant prostate tumor were confirmed, namely the absence of aerobic glycolysis, over-expression of markers, and a strong increase in the concentration of cholesterol and its esters, as well as fatty acids and glutamic acid.AbstractThe possibilities of using optical spectroscopy methods in the differential diagnosis of prostate cancer were investigated. Analytical discrimination models of Raman spectra of prostate tissue were constructed by using the projections onto latent structures data analysis(PLS-DA) method for different wavelengths of exciting radiation—532 and 785 nm. These models allowed us to divide the Raman spectra of prostate cancer and the spectra of hyperplasia sites for validation datasets with the accuracy of 70–80%, depending on the specificity value. Meanwhile, for the calibration datasets, the accuracy values reached 100% for the excitation of a laser with a wavelength of 785 nm. Due to the registration of Raman “fingerprints”, the main features of cellular metabolism occurring in the tissue of a malignant prostate tumor were confirmed, namely the absence of aerobic glycolysis, over-expression of markers (FASN, SREBP1, stearoyl-CoA desaturase, etc.), and a strong increase in the concentration of cholesterol and its esters, as well as fatty acids and glutamic acid. The presence of an ensemble of Raman peaks with increased intensity, inherent in fatty acid, beta-glucose, glutamic acid, and cholesterol, is a fundamental factor for the identification of prostate cancer.     

Differentiation of Normal and Neoplastic Cells by Synchronous Fluorescence: Rat Liver Epithelial and Rat Hepatoma Cell Models

ABSTRACT

In the present study, conventional and synchronous luminescence (SL) were utilized to investigate spectral differences in normal and neoplastic cells. The synchronous fluorescence (SF) method involves scanning simultaneously both emission and excitation wavelengths while keeping a constant wavelength interval between them. This SF procedure simplifies the emission spectrum and provides for greater selectivity and is used to detect subtle differences in the fluorescence emission of the biochemical species of cells from rat tissues. A difference between the fluorescent spectra of the normal rat liver epithelial (RLE) and hepatoma cell lines were detected using synchronous fluorescence. The potential use of SF as a screening tool for cancer diagnosis is discussed.     

Native fluorescence spectroscopy of blood plasma in the characterization of oral malignancy

Native fluorescence characteristics of blood plasma were studied in the visible spectral region, at two different excitation wavelengths, 405 and 420 nm, to discriminate patients with different stages of oral malignancy from healthy subjects. The fluorescence spectra of blood plasma of oral malignant subjects exhibit characteristic spectral differences with respect to normal subjects. Different ratios were calculated using the fluorescence intensity values at those emission wavelengths that give characteristic spectral features of each group of experimental subjects studied. These fluorescence intensity ratios were used as input variables for a multiple linear discriminant analysis across different groups. Leave-one out cross-validation was used to check the reliability of each discriminant analysis performed. The discriminant analysis performed across normal and oral cancerous subjects classified 94.7% of the original grouped cases and 93.7% of the cross-validated grouped cases. A classification algorithm was developed on the basis of the score of the discriminant functions (discriminant score) resulted in the analyses. The diagnostic potentiality of the present technique was also estimated in the discrimination of malignant subjects from normal and nonmalignant diseased subjects such as liver diseases. In the discriminant analysis performed across the three groups, normal, oral malignancy (including early and advanced stages) and liver diseases, 99% of the original grouped cases and 95.9% of the cross-validated grouped cases were correctly classified. Similar analysis performed across normal, early stage of oral malignancy, advanced oral malignancy and liver diseases correctly classified 94.9% of the original grouped cases and 91.8% of the cross-validated grouped cases.     

Autofluorescence of oral tissue for optical pathology in oral malignancy

Pulsed laser-induced-fluorescence studies of pathologically certified oral tissues are carried out at different excitations and time delays. Among the several excitations used, 325 nm produced noticeably different spectral profile for normal and malignant tissues. Extensive curve analysis was carried out in order to understand changes in biochemical composition of tissue based on spectral profiles. Curve resolution and principal component analysis (PCA) show that the fluorescence intensity changes from normal to malignant tissue samples are not completely explained in terms of simple collagen and NAD(P)H intensity changes. The spectra require at least five components to be fully accounted for. Several discrimination methodologies based on PCA and intensity differences between different emission peaks (resultant peaks of curve analysis) were also evaluated. The results obtained indicate PCA using Mahalanobis distance and spectral residual as discrimination parameters provides best discrimination and can be used for matching unknown samples to standard calibration sets. Intensity ratio of bound NAD(P)H to collagen seems to be more suitable for discrimination between normal and malignant oral tissue, compared to ratio of collagen to total intensity of all the other components together.     

Identification and Quantification of Intrinsic Optical Contrast for Near-infrared Mammography

Near-infrared spectroscopy has been used to quantify the composition of healthy female breast tissue in vivo . By collecting transillumination spectra in the wavelength range 680–1100 nm at 7–9 positions on the breasts of five female volunteers, an attempt was made to quantify the intra- and intersubject variability of breast composition. The dominant absorbers are water, lipids and hemoglobin. Hemoglobin concentration in the breast is substantially lower than that in the brain or muscle (less than 10 μ M ). The measured deoxyhemoglobin concentration can vary by up to 100% between different positions on the same breast. Water and lipid concentrations can show similar variability. Phantom and simulation studies demonstrate that this variability is not due to the effects of tissue boundaries on the measurements. The low hemoglobin concentration implies that optical breast imaging should be performed at wavelengths below about 850 nm to ensure that the image contrast comes predominantly from hemoglobin. Intrasubject variability could have implications for the ability of optical imaging to discern tumors from background contrast variations.     

Applicability of surface-enhanced resonance Raman scattering for the direct discrimination of ballpoint pen inks

In situ surface-enhanced resonance Raman spectroscopy (SERRS) with excitation at 685 nm is suitable for the direct discrimination of blue and black ballpoint pen inks on paper. For black inks, shorter excitation wavelengths can also be used. For blue inks, SERRS at 514.5 and 457.9 nm does not provide adequate discriminative power. At these excitation wavelengths, the SERRS signals of the Methyl Violet derivatives present in inks easily dominate the overall spectrum because of resonance enhancement and preferential interaction with silver sol particles. At 685 nm, this problem is not encountered as the Methyl Violet derivatives do not show resonance enhancement, while other components may still exhibit resonance. Thirteen blue and thirteen black ink lines were examined. For the blue and black inks, on the basis of the 685 nm SERR spectra, eight and six groups of spectra, respectively, could be distinguished. This discrimination largely agrees with information from thin layer chromatography (TLC) experiments, although some differences in group compositions are found. The in situ SERR spectra show good repeatability with regard to the Raman frequencies, band shapes and relative intensities of the spectral bands. However, absolute intensities cannot be used for discrimination purposes.     

中红外光纤技术用于口腔肿瘤在体原位检测的研究

肿瘤是严重威胁人类健康和生命的疾病,早期诊断和及时治疗是提高肿瘤病人存活率的重要因素,肿瘤的发生和发展一般可分为3个阶段：(1)基因突变;(2)生物分子组成和结构发生改变;(3)细胞和组织形态发生变化,目前常用的影像学方法只能检测较大的肿块,组织标本的病理诊断法需在     

Autofluorescence microscopy of fresh cervical-tissue sections reveals alterations in tissue biochemistry with dysplasia.

Fluorescence spectroscopy offers an effective, noninvasive approach to the detection of precancers in multiple organ sites. Clinical studies have demonstrated that fluorescence spectroscopy can provide highly sensitive, specific and cost-effective diagnosis of cervical precancers. However, the underlying biochemical mechanisms responsible for differences in the fluorescence spectra of normal and dysplastic tissue are not fully understood. We designed a study to assess the differences in autofluorescence of normal and dysplastic cervical tissue. Transverse, fresh tissue sections were prepared from colposcopically normal and abnormal biopsies in a 34-patient study. Autofluorescence images were acquired at 380 and 460 nm excitation. Results showed statistically significant increases in epithelial fluorescence intensity (arbitrary units) at 380 nm excitation in dysplastic tissue (106 +/- 39) relative to normal tissue (85 +/- 30). The fluorophore responsible for this increase is possibly reduced nicotinamide adenine dinucleotide. Stromal fluorescence intensities in the dysplastic samples decreased at both 380 nm (102 +/- 34 [dysplasia] vs 151 +/- 44 [normal]) and 460 nm excitation (93 +/- 35 [dysplasia] vs 137 +/- 49 [normal]), wavelengths at which collagen is excited. Decreased redox ratio (17-40% reduction) in dysplastic tissue sections, indicative of increased metabolic activity, was observed in one-third of the paired samples. These results provide valuable insight into the biological basis of the differences in fluorescence of normal and precancerous cervical tissue.     

LOCALIZATION OF MONO-L-ASPARTYL CHLORIN e6 (NPe6) IN MOUSE TISSUES

Abstract It is known that HpD is retained longer by malignant tissue than normal tissue and is therefore a useful material for photodynamic therapy (PDT). Currently, vigorous research is being conducted throughout the world to discover a new material which can have greater cancer cell affinity than hematoporphyrin derivative (HpD) and will be used effectively for PDT. Investigation has been conducted to determine the spectral characteristics and cancer cell affinity of NPe6, a recently developed material.
Structurally, a double bond on the D-ring of the porphyrin ring of mono-L-aspartyl chlorin e6 (NPe6) has been reduced, thereby changing its spectral properties from that of HpD. This difference accounts for the stronger absorption bands in wavelengths longer than those of HpD. Furthermore, NPe6 in tumor showed stronger absorption at 660 nm than HpD. Absorption by hemoglobin (Hb) in the blood occurs at wavelengths in the range 500-600 nm, thereby lowering light transmittance. A compound which has a strong absorption band at wavelengths longer than 600 nm and consequently is not affected by Hb will naturally be activated by light at a greater depth in tissue than compounds which do not share this characteristic. The localization of NPe6 in sarcoma and various internal organs was examined with an endoscopic spectrophotometer using an excimer dye laser. After 72 h i.v. NPe6 injection, the results indicate that NPe6 has 10 times greater uptake in malignant tissue cells than in normal organs. Based on the above observations, it was concluded that NPe6 could be effective for PDT if toxicity is low and that this compound has a high malignant tissue affinity.     

Characterization of Adulterated Milk by Two-Dimensional Infrared Correlation Spectroscopy

A new approach for discrimination of adulterated milk is reported using two-dimensional infrared (IR) correlation spectroscopy by multiway principal component analysis (MPCA) and least squares support vector machines (LS–SVM). First, the synchronous two-dimensional spectra of pure and adulterated milk were calculated. Then, MPCA was used to reduce the dimensions, extract features of two-dimensional correlation data set, and distinguish adulterated milk and pure milk. Finally, a LS-SVM model was developed using the scores of the first thirteen principal components from synchronous two-dimensional correlation spectra computed by MPCA as the input variables. The ratios of correct classification were 100% and 96.3% for calibration set and prediction set, respectively. The area under the receiver operating characteristic curves (ROC) of 0.991 for prediction set was obtained by LS–SVM. The results indicate that two-dimensional correlation infrared spectra combined with MPCA–LS–SVM may be a rapid screening technique for discrimination of adulterated milk with good accuracy.     

PbF2:Er3+,Yb3+荧光粉的制备和多波长响应双向转换发光机理

采用高温固相法制备了PbF₂：Er³⁺,Yb³⁺双向转换荧光粉。通过X射线粉末衍射分析（XRD）、结构精修分析、功率-强度测试和荧光光谱分析对样品进行了表征。通过X射线衍射和精修结果分析了样品的相组成和晶胞参数的变化。荧光光谱分析表明,在紫外光（378 nm）和不同波长的红外光（808、980、1 064和1 550 nm）激发下,样品在540~550 nm范围内具有强绿光发射和在650~660 nm范围内的弱红光发射。最后,通过强度-功率测试讨论了样品在不同波长的红外光下激发的上转换发光机理,并分析了在378 nm激发的下转换发光机理。     

Hydrothermal Synthesis of Luminescent Carbon Dots from Glucose and Birch Bark Soot

Carbon dots were prepared by the method of hydrothermal synthesis from carbon precursors of glucose and birch bark soot in aqueous ammonia. The distribution of lateral sizes of carbon dots testifies their average size to be 10–12 nm for glucose and 20–22 nm for soot. Infrared absorption spectra indicate oxygen groups on the surfaces of obtained carbon dots. Aqueous suspensions with glucose-based carbon dots exhibit strong absorption in the visible region from 300 nm to 500 nm. Soot-based carbon dots demonstrate strong absorption in the ultraviolet region, but are transparent in the visible region. The luminescence spectra exhibit that carbon dots synthesized from glucose and soot are luminescent in the same spectral region, their wavelengths of radiation depend on the wavelengths of excitation, and the intensity of luminescence depends on the presence of oxygen groups on the surface of carbon dots. Carbon dots synthesized from glucose and soot have great prospects in terms of their application in biology and medicine.     

The use of synchronous luminescence spectroscopy in qualitative analysis of aromatic fraction of hard coal thermolysis products

The synchronous luminescence method was used in qualitative analysis of aromatic fraction of low-temperature tar from hard coal. The spectra obtained by this method are simpler than spectra obtained with the use of conventional emission luminescence method. The synchronous luminescence analysis requires the selection of respective Deltalambda parameter values. This parameter is a constant difference between position of excitation and emission monochromators during measurement. From literature, the Deltalambda parameter value of 23 nm was first used here. The characteristic emission ranges of spectra obtained indicated (by comparison with spectra of standards) degree of condensation of aromatic compounds present in investigated mixtures. It was also possible to identify some individual compounds. However, this identification could be more effective with the use of the respective value of Deltalambda parameter for each particular component of the mixture. This manner of analysis was used here, e.g. for investigating aromatic fraction containing phenanthrene (identified previously by gas chromatography method) among other compounds. The spectrum recorded at Deltalambda value characteristic for phenanthrene (53nm) presents a rather simple shape with a maximum at 346 nm attributed to phenanthrene after standard and literature data.     

Raman endoscopy for in vivo differentiation between benign and malignant ulcers in the stomach

The aim of this study was to evaluate the clinical utility of an image-guided Raman endoscopy technique for in vivo differential diagnosis of benign and malignant ulcerous lesions in the stomach. A rapid-acquisition image-guided Raman endoscopy system with 785 nm laser excitation has been developed to acquire in vivo gastric tissue Raman spectra within 0.5 s during clinical gastroscopic examinations. A total of 1102 in vivo Raman spectra were acquired from 71 gastric patients, in which 924 Raman spectra were from normal tissue, 111 Raman spectra were from benign ulcers whereas 67 Raman spectra were from ulcerated adenocarcinoma. There were distinctive spectral differences in Raman spectra among normal mucosa, benign ulcers and malignant ulcers, particularly in the spectral ranges of 800-900, 1000-1100, 1245-1335, 1440-1450 and 1500-1800 cm(-1), which primarily contain signals related to proteins, DNA, lipids and blood. The malignant ulcerous lesions showed Raman signals to be mainly associated with abnormal nuclear activity and decrease in lipids as compared to benign ulcers. Partial least squares-discriminant analysis (PLS-DA) was employed to generate multi-class diagnostic algorithms for classification of Raman spectra of different gastric tissue types. The PLS-DA algorithms together with leave-one tissue site-out, cross validation technique yielded diagnostic sensitivities of 90.8%, 84.7%, 82.1%, and specificities of 93.8%, 94.5%, 95.3%, respectively, for classification of normal mucosa, benign and malignant ulcerous lesions in the stomach. This work demonstrates that image-guided Raman endoscopy technique associated with PLS-DA diagnostic algorithms has for the first time promising clinical potential for rapid, in vivo diagnosis and detection of malignant ulcerous gastric lesions at the molecular level.