Distinguishing malignant from normal stomach tissues and its in vivo, in situ measurement in operating process using FTIR Fiber-Optic techniques

The application of molecular spectroscopy inthe biological fields is more and more extensive.Recently vibrational spectroscopy, including FTIRATR Optic Fibers[1—3], FT-IR microspectroscopy[4—6],FT-Raman[7,8] and near IR spectroscopic[9] methods,was used…     

Distinguishing malignant from normal stomach tissues and its <Emphasis Type="Italic">in vivo,in situ</Emphasis> measurement in operating process using FTIR Fiber-Optic techniques

Gastric tissue samples were studied using mid-IR fiber-optic attenuated total reflectance (ATR) spectroscopy. FTIR spectra of 90 tissue samples from 48 patients, including 32 normal and 58 malignant tissue samples, were chosen as examples. Malignancy was usually characterized by the absence of CH and C=O bands, a weak amide II band near 1545 cm^-1, a shift of the amide I band to lower wave number, a decrease in the ∼1450 cm^-1 peak to less than the ∼ 1400 cm^-1 peak. Subtraction spectra indicate that the amide I and amide II bands of normal and malignant tissues have larger differences in peak positions and relative intensities. The statistical analysis results confirm this conclusion. The results indicate that FTIR fiber optic techniques provide important information about cancerous tissue of the stomach, which can be used to differentiate the malignant tissue from the normal tissue. Based on the above results we successfully realize the detection of the tumor tissues of digestive tract in vivo and in situ. And the results of detection cancer near operating room and in vivo and in situ in the operating room are consistent with the conclusions for the samples stored in liquid N², which is the basis for the clinical application.     

Subsurface sensing of biomedical tissues using a miniaturized Raman probe: study of thin-layered model samples

A ball lens hollow-fiber Raman probe (BHRP) is a powerful tool for in vivo nondestructive subsurface analysis of biomedical tissues in a living body. It has confocal-like optical properties, but its collection volume is rather large in comparison with that of a conventional confocal Raman system. Therefore, the obtained Raman spectra have contributions from the upper and lower layers at different rates depending on the thickness of the upper layer when the measurement point is close to the boundary surface of the two layers. In the present study, we describe a methodology to extract quantitative information about the thickness of the subsurface layer structure by using a BHRP combined with the partial least-square regression (PLSR) analysis. The simulation study indicates that distribution of the collection efficiency in the collection volume of the BHRP is similar to a Gaussian distribution. The empirical study suggests that the PLSR model built with only a principal component (PC) 1 based on the linearized depth data gives good prediction.     

Raman and FTIR spectroscopic characterization of electrochemically synthesized poly(triphenylamine), PTPA

Triphenylamine was electrochemically polymerized in a mixture of toluene and acetonitrile with different electrolyte salts. The poly(triphenylamine) (PTPA) films are insoluble in polar solvents and show high stability and no degradation or loss in electrochemical properties when stored in a laboratory atmosphere. The PTPA films were characterized in situ by FTIR external reflection spectroscopy and by Raman spectroscopy. Electronic Publication     

水合铵硼氧酸盐及其饱和溶液的FTIR和Raman光谱研究

研究了NH₄B₅O₈·4H₂O和(NH₄)₂B₈O₁₃·6H₂O及其饱和溶液于20℃的FTIR和Raman光谱,对振动频率进行了归属.根据振动光谱特征,预测(NH₄)₂B₈O₁₃·6H₂O中所含基本结构单元为[B₇O ₁₁(OH)·B(OH)₃]^2-.首次将Raman光谱中516cm^-1处的强散射峰归属为这一多聚硼氧配阴离子的对称脉冲振动峰,并对以上2种铵硼氧酸盐饱和溶液中硼氧配阴离子的存在形式{B(OH)₃,[B₃O₃(OH)₄]^-和[B₅O₆(OH)₄]^-}和相互作用机理进行了探讨.     

Methodology for fiber-optic Raman mapping and FTIR imaging of metastases in mouse brains

The objectives of this study were to optimize the preparation of pristine brain tissue to obtain reference information, to optimize the conditions for introducing a fiber-optic probe to acquire Raman maps, and to transfer previous results obtained from human brain tumors to an animal model. Brain metastases of malignant melanomas were induced by injecting tumor cells into the carotid artery of mice. The procedure mimicked hematogenous tumor spread in one brain hemisphere while the other hemisphere remained tumor free. Three series of sections were prepared consecutively from whole mouse brains: dried, thin sections for FTIR imaging, hematoxylin and eosin-stained thin sections for histopathological assessment, and pristine, 2-mm thick sections for Raman mapping. FTIR images were recorded using a spectrometer with a multi-channel detector. Raman maps were collected serially using a spectrometer coupled to a fiber-optic probe. The FTIR images and the Raman maps were segmented by cluster analysis. The color-coded cluster memberships coincided well with the morphology of mouse brains in stained tissue sections. More details in less time were resolved in FTIR images with a nominal resolution of 25 microm than in Raman maps collected with a laser focus 60 microm in diameter. The spectral contributions of melanin in tumor cells were resonance enhanced in Raman spectra on excitation at 785 nm which enabled their sensitive detection in Raman maps. Possible reasons why metastatic cells of malignant melanomas were not identified in FTIR images are discussed.     

Raman spectroscopic study on classification of cervical cell specimens

Cervix-cancer is the third most common female cancer worldwide. Papanicolaou (Pap) test, a well-recognized screening tool, is labor intensive, time consuming and prone to subjective interpretations. Optical spectroscopic methods, sensitive to molecular changes are being pursued as potential diagnostics tool. In this study we have explored Raman spectroscopic approach to differentiate exfoliated cell pellets using 94 cervical cell specimens (45-normal and 49-abnormal specimens). Study was carried out by two approaches. In the first approach, spectral data from 37 cell specimens were acquired and analyzed by Principal Component-Linear Discriminant Analysis (PC-LDA), which yielded classification efficiencies of 86% and 84% for normal and abnormal specimens, respectively. Mean and difference spectra suggest presence of blood in abnormal specimen as a major cause of discrimination. However, as tumor is vascular, bleeding was observed during abnormal sample collection. Hence, spectra of abnormal specimens show heme and fibrin features, and this can lead to false interpretations, as bleeding also occur in several non-cancerous conditions. Therefore, remaining 57 specimens were treated with Red Blood Corpuscles (RBC) lysis buffer in order to remove the RBC influence. PC-LDA resulted classification efficiency of about 79% and 78% for normal and abnormal smear, respectively – comparable to Pap test. Thus finding of the study suggests feasibility of Raman spectroscopic classification of normal and cancerous exfoliated cervical cell specimens.     

Nutritional parameters of commercially available milk samples by FTIR and chemometric techniques

A chemometric study on the prediction of the main nutritional aspects of milk has been carried out by using fourier transform infrared spectroscopy (FTIR) attenuated total reflectance (ATR) measurements of commercially available milk samples of different types. Whole, semi and skimmed milks, enriched or not with calcium, vitamins or modified by alteration of lipid or sugar composition were considered. After evaluating different strategies for data acquisition and ATR cleaning between samples, hierarchical cluster analysis (HCA) was carried out for classification of samples in order to choose the calibration set. The prediction capabilities of partial least squares (PLS) data treatment were evaluated in order to obtain information about total fat, total protein, total carbohydrates (CH), calories and calcium. On using the mean square error of cross-validation and prediction as control variables, a critical evaluation were made about the calibration set to be used, the spectral range to be considered and the data treatment (PLS-1 or PLS-2) to be performed. By selecting a calibration set of 33 samples the properties of 48 samples were predicted with relative precision of triplicates of 0.062, 0.040 and 0.039% w/v for total fat, protein and carbohydrates, and 0.66 kcal/100 ml for calories, and 2.1 mg of Ca/100 ml. The mean difference (d_x−y) between predicted and actual values and standard deviation of mean differences (s_x−y), were of 0.06 (0.38), 0.03 (0.18) and −0.15 (0.41), being s_x−y values between brackets, for total fat, proteins and carbohydrates, 0.06 (3.8) kcal/100 ml for calories and −4.5 (9) mg/100 ml for calcium.The sensitivity and selectivity of the methodology developed were evaluated on terms of the net analyte signal. Selectivity factors ranging from 2 to 7.6% have been calculated for the five parameters considered.     

Classification of normal and malignant human gastric mucosa tissue with confocal Raman microspectroscopy and wavelet analysis

Thirty-two samples from the human gastric mucosa tissue, including 13 normal and 19 malignant tissue samples were measured by confocal Raman microspectroscopy. The low signal-to-background ratio spectra from human gastric mucosa tissues were obtained by this technique without any sample preparation. Raman spectral interferences include a broad featureless sloping background due to fluorescence and noise. They mask most Raman spectral feature and lead to problems with precision and quantitation of the original spectral information. A preprocessed algorithm based on wavelet analysis was used to reduce noise and eliminate background/baseline of Raman spectra. Comparing preprocessed spectra of malignant gastric mucosa tissues with those of counterpart normal ones, there were obvious spectral changes, including intensity increase at approximately 1156cm(-1) and intensity decrease at approximately 1587cm(-1). The quantitative criterion based upon the intensity ratio of the approximately 1156 and approximately 1587cm(-1) was extracted for classification of the normal and malignant gastric mucosa tissue samples. This could result in a new diagnostic method, which would assist the early diagnosis of gastric cancer.     

Discriminant analysis of trace elements in normal,benign and malignant breast tissues measured by total reflection X-ray fluorescence

In this work total reflection X-ray fluorescence spectrometry has been employed to determine trace element concentrations in different human breast tissues (normal, normal adjacent, benign and malignant). A multivariate discriminant analysis of observed levels was performed in order to build a predictive model and perform tissue-type classifications. A total of 83 breast tissue samples were studied. Results showed the presence of Ca, Ti, Fe, Cu and Zn in all analyzed samples. All trace elements, except Ti, were found in higher concentrations in both malignant and benign tissues, when compared to normal tissues and normal adjacent tissues. In addition, the concentration of Fe was higher in malignant tissues than in benign neoplastic tissues. An opposite behavior was observed for Ca, Cu and Zn. Results have shown that discriminant analysis was able to successfully identify differences between trace element distributions from normal and malignant tissues with an overall accuracy of 80% and 65% for independent and paired breast samples respectively, and of 87% for benign and malignant tissues.     

Exploration of Raman exfoliated cytology for oral and cervical cancers

Exfoliated cell are one of the most patient compliant specimens, hence are workhorse of successful screening programs in cancers like cervix. Raman exfoliative cytology (REC), even on cell pellets using Raman microprobe, has demonstrated ∼80% specificity, comparable to conventional screening programs. Objective of this study is to further evaluate Raman spectroscopy, which is sensitive to biochemical composition, vis-a-vis conventional morphology based cytology that differentiates cell-type but not the origin. Exploration of this kind further corroborates utility and efficacy of REC as screening tool, also can pave way to prospective multi-cancer screening by a multi-group model. Therefore, the present study explores REC in a stringent two-cancer, four-group model for classification of 44 oral [29, tumor (OT), 15 normal (ON)] and 66 cervical (38 tumor (CT), 28 normal (CN)] exfoliated cell specimens. Spectra were acquired from cell pellets using Raman microprobe. Spectra were analyzed in two approaches, spectra-wise and subject-wise to circumvent inherent heterogeneity due to co-localization of normal cells in malignant specimens. In the first approach, PCA and LDA yielded a classification efficiency of 82% for OT and 77% for CT. A slightly higher classification (OT, 86% and CT, 84%) was achieved for the subject-wise approach. Thus findings of this study demonstrate similar efficacy and specificity to that of individual cancer-based models reported earlier. These findings are quite encouraging especially for resource deprived and under privileged countries where these two cancers are more prevalent and could be useful for prospective centralized REC facility.     

Laser Raman and FTIR studies on Li+ interaction in PVAc-LiClO4 polymer electrolytes

The polymer electrolytes composed of poly(vinyl acetate) (PVAc) with various stoichiometric ratios of lithium perchlorate (LiClO(4)) salt have been prepared by solution casting method. The techniques Fourier transform infra-red (FTIR) and Laser Raman spectroscopy have been used to monitor polymer-salt complex formation, ion-ion and ion-polymer interactions as a function of salt concentration. Significant changes in both Laser Raman and FTIR spectra are observed which reveals an interaction between ester oxygens with lithium cation coordination. These results strongly suggest the interaction of lithium cation and network polymer chains. When the salt content is increased, the intensity of the internal Raman modes of the ClO(4)(-) increases. The ClO(4)(-) stretching mode observed at 934 cm(-1) in Laser Raman shows some additional shoulder peaks with increase in salt concentration. This reveals the presence of free anions, ion contact pairs and higher order ionic clusters. From the FTIR and Laser Raman results the transport mechanism of ions in PVAc:LiClO(4) polymer electrolytes has been discussed.     

Surface-enhanced Raman Scattering of Self-assembled Superstructures

Surface-enhanced Raman scattering(SERS) is a molecular specific spectroscopic technique that amplifies the Raman signal of absorbed molecules for up to 10¹⁰times. Over the past decades, SERS substrates experienced rapid growth, resulting in excellent development for SERS analysis. Because the surface plasmonic resonance coupling between individual materials can form a "hotspot" region to maximize the Raman signal, among many substrate construction strategies, self-assembly attracts more attention in constructing superstructures with strong, uniform and stable SERS activity. In addition, a number of plasmon-free nanomaterials with appropriate superstructures samely show enhanced SERS activity, which is primarily attributed to the formation of the optical resonator. This review aims to provide a scientific synopsis on the progress of self-assembled superstructures for SERS and ignite new dis˗ coveries in the SERS platform, as well as SERS applications in various fields.     

Quantum chemical determination of molecular geometries and interpretation of FTIR and Raman spectra for 2,3,4-and 2,3,6-tri-fluoro-benzonitriles

Raman and FTIR spectra for 2,3,4- and 2,3,6-tri-fluoro-benzonitriles have been recorded in the regions 50–4000 cm⁻¹ and 400–4000 cm⁻¹, respectively. Measurement of depolarization ratios for the Raman lines has also been made. Optimized geometrical parameters, charge distributions and vibrational wavenumbers were calculated using ab initio quantum chemical method. Normal coordinate analysis has also been carried out to help assign the fundamentals of these molecules. Each vibration has been assigned using observed wavenumbers in the IR and Raman spectra and their relative intensities, depolarization ratios of the Raman lines, the calculated frequencies, vector displacements and potential energy distributions (PEDs).     

Vibrational analysis of 4-amino pyrazolo (3,4-d) pyrimidine A joint FTIR, Laser Raman and scaled quantum mechanical studies

The FTIR and Laser Raman spectra of 4-amino pyrazolo (3,4-d) pyrimidine have been measured in the regions 4000–400 cm⁻¹ and 3500–100 cm⁻¹, respectively. Utilizing the observed FTIR and Laser Raman data, a complete vibrational assignment and analysis of the fundamental modes of the title compound were carried out. The vibrational frequency which were determined experimentally are compared with those theoretically from force field calculation based on ab initio HF/6−311+G**(d,p) and standard B3LYP/6−311+G**(d,p) methods and basis set combinations for optimized geometries. The observed FTIR and Laser Raman vibrational frequencies were analysed and compared with the theoretically predicted vibrational frequencies. The assignments of bands to various normal modes of the molecules were also carried out. A detailed interpretation of the infrared and Raman spectra of 4-amino pyrazolo (3,4-d) pyrimidine [4AP(3,4-D)P] is also reported based on total energy distribution (TED). The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The theoretical FT-IR and FT-Raman spectra for the title molecule have also been constructed.     

Synthesis,structural study,thermal, optical properties and characterization of the new compound [C_6H_7N_2O_2]_3TeCl_5·2Cl

The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system (P~-1) with the following parameters: a = 10.5330(11) ?, b = 10.6663(11) ?, c = 15.9751(16)?, α = 82.090(2)°, β = 71.193(2)°, γ = 68.284(2)°and Z = 2. The final cycle of refinement led to R = 0.057 and Rw = 0.149. The crystal structure was stabilized by an extensive network of N--H···Cl and non-classical C--H···Cl hydrogen bonds between the cation and the anionic group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to determine the kinetics parameters. We observe that the decomposition of [C_6H_7N_2O_2]_3TeCl_5·2Cl entails the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the4000–400 cm~(-1)frequency region. The Raman spectra were recorded in the external region of the anionic sublattice vibration 50–1500 cm~(-1). The optical band gap was calculated from the UV-Vis absorbance spectra using classical Tauc relation which was found to be 3.12 and 3.67 eV.     

Application of FTIR imaging to detect dietary induced biochemical changes in brown and white adipocytes

Fourier Transform Infrared microspectroscopy Imaging (FTIR imaging) has powerful advantages when used as a complementary technique to histopathological investigations. The common histopathological investigations use a number of chemical fixatives and deparaffinizing agents that alter lipid profiles of biological tissues, particularly in lipid-rich adipose tissues. An infrared image is made of a multitude of pixels. For each pixel, identified by its (x,y) coordinates, corresponds an FTIR spectrum that reveals the chemical composition at this specific location. As a result, it allows biochemical analysis in selective locations within samples. Moreover, functional group distribution maps can be used as a staining free technique for spatial characterization of different biomolecules. Though FTIR imaging has been reported as a powerful approach to characterize adipose tissues, the biochemical heterogeneity within adipose tissues has not been acknowledged. This study shows relative changes in brown and white adipose tissues of mice due to consumption of high-fat diet. In particular, we report cryosectioning of adipose tissues, image acquisition, and different image analysis methods to evaluate dietary induced changes in lipids stored in brown and white adipocytes. Since biochemical changes in adipocytes constitute an important component in obesity investigations, this study shows the potential use of FTIR imaging to compare relative biochemical changes associated with dietary interventions.     

Mechanistic study of partial oxidation of methane to syngas using in situ time-resolved FTIR and microprobe Raman spectroscopies

In situ time-resolved Fourier transform infrared (FTIR) and microprobe Raman spectroscopies were used to characterize the reaction mechanisms of the partial oxidation of methane to syngas over SiO(2)- and gamma-Al(2)O(3)-supported rhodium and ruthenium catalysts. The interaction of both pure methane and a methane/oxygen mixture at a stoichiometric feed ratio with an oxygen-rich catalyst surface led to the formation of CO2 and H(2)O as the primary products. For the H(2)-pretreated samples, the reaction mechanisms with the catalysts differ. Only Rh/SiO(2) is capable of catalyzing the direct oxidation of methane to syngas, while syngas formation over Rh/gamma-Al(2)O(3), Ru/SiO(2), and Ru/gamma-Al(2)O(3) can be achieved mainly via a combustion-reforming scheme. The significant difference in the mechanisms for partial oxidation of methane to syngas over the catalysts can be correlated to the differences in the concentration of oxygen species (O(2-)) on the catalyst surface during the reaction, mainly due to the difference in the nature of the metals and supports.     

Crisp and soft multivariate methods visualize individual cell nuclei in Raman images of liver tissue sections

Raman and infrared spectroscopy have been recognized to be promising tools in clinical diagnostics because they provide molecular contrast without external stains. Here, vertex component analysis (VCA) was applied to Raman and Fourier transform infrared (FTIR) images of liver tissue sections and the results were compared with K-means cluster analysis, fuzzy C-means cluster analysis and principal component analysis. The main components of VCA from three Raman images were assigned to the central vein, periportal vein, cell nuclei, liver parenchyma and bile duct. After resonant Mie scattering correction, VCA of FTIR images identified veins, liver parenchyma, cracks, but no cell nuclei. The advantages of VCA in the context of tissue characterization by vibrational spectroscopic imaging are that the tissue architecture is visualized and the spectral information is reconstructed. Composite images were constructed that revealed a high molecular contrast and that can be interpreted in a similar way like hematoxylin and eosin stained tissue sections.