Depth‐resolved in vivo micro‐Raman spectroscopy of a murine skin tumor model reveals cancer‐specific spectral biomarkers

We have developed a micro‐Raman spectrometer system for use to differentiate tumor lesions from normal skin using an in vivo animal model. A study of 494 Raman spectra from 24 mice revealed different spectral patterns at different depths and between normal and tumor‐bearing skin sites. A peak at 899 cm⁻¹ (possibly from proline or fatty acids) and one with higher intensity in the 1325–1330 cm⁻¹ range (assigned to nucleic acids) were correlated with the presence of tumors, which can potentially be used as biomarkers for skin cancer detection. Spectral diagnosis performed on the murine tumor model achieved a diagnostic sensitivity of 95.8% and specificity of 93.8%. These results encourage us to develop further the use of confocal Raman spectroscopy as a clinical tool for noninvasive human skin biochemical analysis, particularly in relation to skin cancer. Copyright © 2010 John Wiley & Sons, Ltd.     

Raman spectral signatures of mouse mammary tissue and associated lymph nodes: normal,tumor and mastitis

Raman spectroscopy involves the interaction of light with the molecular vibrations and therefore can provide information about molecular structure, tissue composition and changes in its environment. We explored whether Raman spectroscopy can reliably distinguish mammary tumors from normal mammary tissues and other pathological states in mice. We analyzed a large number of Raman spectra from the tumor and normal mammary glands of mice injected with 4T1 tumor cells, which were collected using a high‐resolution (less than 4 cm⁻¹) Raman spectrometer at a fixed (785 nm) laser excitation wavelength and with 60 mW of laser power. The spectra of normal and tumor mammary glands showed consistent differences in the intensity of certain Raman bands and loss of some bands in the tumor spectra. Multivariate statistical methods—principal component analysis (PCA) and discriminant functional analysis (DFA)—were used to separate the data into different groups of mammary tumors, mastitis, lymph nodes contralateral and tumor‐cell‐injected sides, and normal contralateral and tumor‐cell‐injected sides. We demonstrate that this spectroscopic technique has the feasibility of discriminating tumor and mastitis from normal tissues and other pathological states in a short period of time and may detect tumor transformation earlier than the standard histological examination stage. Copyright © 2006 John Wiley & Sons, Ltd.     

Depth profiling of porcine adipose tissue by Raman spectroscopy

Raman spectroscopy was applied on a depth profile of porcine adipose tissue (from skin to meat) with the purpose of (1) discriminating between fat layers and (2) estimating the variation in fatty acid composition as a function of fat depth and fat layer: total degree of unsaturation (iodine value), fractions of saturated, and monounsaturated and polyunsaturated fatty acids. The thickness and composition of the outer layer of porcine adipose tissue influences the final quality of backfat. A too‐thick outer layer is associated with problems such as oily appearance, rancidity development, and difficulties in separating muscle and adipose tissue when cutting. From principal component analysis on standard normal variate preprocessed Raman spectra (1800–800 cm^–1), it was possible to discriminate between the outer and the inner backfat layer. Principal component analysis loadings showed that the separation of layer was mainly explained by variation in the bands originating from vibration of double bond C = C stretching plus = C–H twisting and rocking. In the prediction of iodine value a three‐component partial least squares regression model based on full range Raman spectra showed a root mean square error of cross validation of 2.00 and R² = 0.69. Applying Cauchy–Lorentz band fitting proved that information regarding fat unsaturation was found not only in band intensity, but also in band parameters such as location and width. The results suggest Raman spectroscopy as a potential measurement technique for rapid grading of pork carcasses. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparison of molecular images as defined by Raman spectra between normal mucosa and squamous cell carcinoma in the oral cavity

Raman spectroscopy has been effectively applied to clinically differentiate normal and cancerous mucosal tissues. Micro‐Raman spectroscopy provides a tool to better understand the molecular basis for the Raman clinical signal. The objective of the current study was to utilize micro‐Raman spectroscopy to define the molecular/spectral differences between normal and abnormal squamous cell carcinoma (SCC) in oral mucosa (in vitro). Understanding this may help in identifying unique spectra or may be useful for in vivo application of this technology. Micro‐Raman (confocal) spectroscopy was used to obtain molecular images of normal and SCC cells of human oral mucosa. Four fresh flashed‐frozen tumor and four matched normal tongue specimens were studied. The spectra covered a wavenumber range from 300 to 4000 cm⁻¹ with a spectral resolution of 8 cm⁻¹ and a spatial resolution of 1.0 µm. The cells were located within thin sections of tongue mucosa biopsies. The excitation wavelength of 515 nm was used. We were able to obtain Raman images with rich information about the spectroscopic and structural features within the cytoplasm, cell membrane, and cell nuclei. Significant spectral differences were observed between the Raman images of normal and malignant squamous cells. The heterogeneity of tumor cells within the abnormal tissue was also demonstrated. Spectral differences demonstrated between both tissue types have provided important information regarding the origins of specific signals within the cells of each tissue type. In our search for specific spectral biomarkers, we believe that a cell surface protein, greatly upregulated in SCC cells, was discovered at 1583 cm⁻¹. Copyright © 2010 John Wiley & Sons, Ltd.     

Qualitative analysis of desi ghee,edible oils,and spreads using Raman spectroscopy

Keeping in view the importance of dietary fats in modulating disease risk, a study was planned to compare edible oils, spreads, and desi ghee based on fatty acid composition through Raman spectroscopy. The double bonds in unsaturated oils tend to react more with oxygen causing oxidative stress in living cells; therefore, the excessive use of processed vegetable oils may pose risk for human health. In the spectral analysis, Raman peaks at 1063 and 1127 cm⁻¹ represent out‐of‐phase and in‐phase aliphatic C C stretch for saturated fatty acids. The peak at 1300 cm⁻¹, labeled for alkane, decreases with increase in the double bond contents (unsaturation). Further, the Raman peak at 1655 cm⁻¹ showed a monotonic increase as a function of unsaturation. The double bond contents in the Raman spectra from 1650–1657 cm⁻¹ represent unsaturated fatty acids that changes during the synthesis of spreads and banaspati ghee. Desi ghee, extracted from cow and buffalo milk, showed distinctive Raman peaks at 1650 and 1655 cm⁻¹, which originates because of isomers of conjugated linoleic acid. These Raman shifts differentiated desi ghee from other artificially produced banaspati ghee, spreads, and oils. Conjugated linoleic acid has proved to be anti‐carcinogenic, anti‐inflammatory, and anti‐allergic properties; therefore, the limited use of desi ghee may reduce the risk of cardiac diseases. Principal component analysis has been applied on the Raman spectra that clearly differentiated desi ghee, mono‐unsaturated extra virgin olive oil, and extra virgin olive oil spread from other oils, oil mixtures, spreads, and ghee. In addition, principal component analysis has been blindly applied successfully on 13 unknown samples to classify them with reference to the known ghee sample. Copyright © 2016 John Wiley & Sons, Ltd.     

Raman spectroscopic study of the antimonate mineral brandholzite Mg[Sb2(OH)12]·6H2O

Raman spectra of brandholzite Mg[Sb₂(OH)₁₂]·6H₂O were studied, complemented with infrared spectra, and related to the structure of the mineral. An intense Raman sharp band at 618 cm⁻¹ is attributed to the SbO symmetric stretching mode. The low‐intensity band at 730 cm⁻¹ is ascribed to the SbO antisymmetric stretching vibration. Low‐intensity Raman bands were found at 503, 526 and 578 cm⁻¹. Corresponding infrared bands were observed at 527, 600, 637, 693, 741 and 788 cm⁻¹. Four Raman bands observed at 1043, 1092, 1160 and 1189 cm⁻¹ and eight infrared bands at 963, 1027, 1055, 1075, 1108, 1128, 1156 and 1196 cm⁻¹ are assigned to δ SbOH deformation modes. A complex pattern resulting from the overlapping band of the water and hydroxyl units is observed. Raman bands are observed at 3240, 3383, 3466, 3483 and 3552 cm⁻¹; infrared bands at 3248, 3434 and 3565 cm⁻¹. The Raman bands at 3240 and 3383 cm⁻¹ and the infrared band at 3248 cm⁻¹ are assigned to water‐stretching vibrations. The two higher wavenumber Raman bands observed at 3466 and 3552 cm⁻¹ and two infrared bands at 3434 and 3565 cm⁻¹ are assigned to the stretching vibrations of the hydroxyl units. Observed Raman and infrared bands in the OH stretching region are associated with O‐H···O hydrogen bonds and their lengths 2.72, 2.79, 2.86, 2.88 and 3.0 Å (Raman) and 2.73, 2.83 and 3.07 Å (infrared). Copyright © 2009 John Wiley & Sons, Ltd.     

A vibrational spectroscopic investigation of rhodanine and its derivatives in the solid state

Raman and infrared spectra are reported for rhodanine, 3‐aminorhodanine and 3‐methylrhodanine in the solid state. Comparisons of the spectra of non‐deuterated/deuterated species facilitate discrimination of the bands associated with N H, NH₂, CH₂ and CH₃ vibrations. DFT calculations of structures and vibrational spectra of isolated gas‐phase molecules, at the B3‐LYP/cc‐pVTZ and B3‐PW91/cc‐pVTZ level, enable normal coordinate analyses in terms of potential energy distributions for each vibrational normal mode. The cis amide I mode of rhodanine is associated with bands at ∼1713 and 1779 cm⁻¹, whereas a Raman and IR band at ∼1457 cm⁻¹ is assigned to the amide II mode. The thioamide II and III modes of rhodanine, 3‐aminorhodanine and 3‐methylrhodanine are observed at 1176 and 1066/1078; 1158 and 1044; 1107 and 984 cm⁻¹ in the Raman and at 1187 and 1083; 1179 and 1074; 1116 and 983 cm⁻¹ in the IR spectra, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

Vibrational spectroscopic studies of the structure of di‐amino acid peptides. Part II: cyclo(L‐Asp‐L‐Asp) in the solid state and in aqueous solution

Solid‐state protonated and N,O‐deuterated Fourier transform infrared (IR) and Raman scattering spectra together with the protonated and deuterated Raman spectra in aqueous solution of the cyclic di‐amino acid peptide cyclo(L ‐Asp‐L ‐Asp) are reported. Vibrational band assignments have been made on the basis of comparisons with previously cited literature values for diketopiperazine (DKP) derivatives and normal coordinate analyses for both the protonated and deuterated species based upon DFT calculations at the B3‐LYP/cc‐pVDZ level of the isolated molecule in the gas phase. The calculated minimum energy structure for cyclo(L ‐Asp‐L ‐Asp), assuming C₂ symmetry, predicts a boat conformation for the DKP ring with both the two L ‐aspartyl side chains being folded slightly above the ring. The CO stretching vibrations have been assigned for the side‐chain carboxylic acid group (e.g. at 1693 and 1670 cm⁻¹ in the Raman spectrum) and the cis amide I bands (e.g. at 1660 cm⁻¹ in the Raman spectrum). The presence of two bands for the carboxylic acid CO stretching modes in the solid‐state Raman spectrum can be accounted for by factor group splitting of the two nonequivalent molecules in a crystallographic unit cell. The cis amide II band is observed at 1489 cm⁻¹ in the solid‐state Raman spectrum, which is in agreement with results for cyclic di‐amino acid peptide molecules examined previously in the solid state, where the DKP ring adopts a boat conformation. Additionally, it also appears that as the molecular mass of the substituent on the C^α atom is increased, the amide II band wavenumber decreases to below 1500 cm⁻¹; this may be a consequence of increased strain on the DKP ring. The cis amide II Raman band is characterized by its relatively small deuterium shift (29 cm⁻¹), which indicates that this band has a smaller N H bending contribution than the trans amide II vibrational band observed for linear peptides. Copyright © 2009 John Wiley & Sons, Ltd.     

Raman spectroscopy of smithsonite

Raman spectroscopy at both 298 and 77 K has been used to study a series of selected natural smithsonites from different origins. An intense sharp band at 1092 cm⁻¹ is assigned to the CO₃²⁻ symmetric stretching vibration. Impurities of hydrozincite are identified by a band around 1060 cm⁻¹. An additional band at 1088 cm⁻¹ which is observed in the 298 K spectra but not in the 77 K spectra is attributed to a CO₃²⁻ hot band. Raman spectra of smithsonite show a single band in the 1405–1409 cm⁻¹ range assigned to the ν₃ (CO₃)²⁻ antisymmetric stretching mode. The observation of additional bands for the ν₃^g modes for some smithsonites is significant in that it shows distortion of the ZnO₆ octahedron. No ν₂ bending modes are observed for smithsonite. A single band at 730 cm⁻¹ is assigned to the ν₄ in phase bending mode. Multiple bands be attributed to the structural distortion are observed for the carbonate ν₄ in phase bending modes in the Raman spectrum of hydrozincite with bands at 733, 707 and 636 cm⁻¹. An intense band at 304 cm⁻¹ is attributed to the ZnO symmetric stretching vibration. Copyright © 2007 John Wiley & Sons, Ltd.     

Raman fingerprint of the interaction of K+ with the COO− group of zwitterionic alanine

The interaction of K⁺ with the zwitterionic form of alanine (ZAla) is investigated using Raman spectroscopy and density functional theory calculations. The Raman spectra of an aqueous solution of Ala and its mixture with KOH at different molar concentrations [ZAla + xKOH, x = 1–5 M] have been recorded in the spectral region 400–1800 cm⁻¹. The wavenumber position of the band at ~529 cm⁻¹ shows a red shift of 14 cm⁻¹, while the Raman band at ~634 cm⁻¹ shows a blue shift of 10 cm⁻¹ with the increasing x from 1 to 5 M. The intensity ratio I₆₃₄/I₅₂₉ is increased with increasing x, and it could be because of the increase in concentration of the [ZAla + K⁺] complex in the solution. The new Raman band appeared at ~1079 cm⁻¹ in the Raman spectra of [ZAla + xKOH, x = 1–5] complex. To determine the most probable site for the interaction of K⁺ with ZAla, the structures of ZAla and the [ZAla + K⁺] were optimized at B3LYP/6‐311++G(d,p) level of theory. The electrostatic potential calculation carried out for ZAla reveals that the maximum density of electron is lying over COO⁻, and therefore, COO⁻ would be the most probable site for the interaction of K⁺ with ZAla. The theoretically calculated Raman spectra of ZAla, [ZAla + K⁺] and the [ZAla⁻ + K⁺] are in good agreement with experimentally observed Raman spectra. Thus, the Raman bands at ~529, 634, and 1079 cm⁻¹ may be used as the Raman fingerprint for the interaction of K⁺ with COO⁻ of the ZAla and ZAla⁻. Copyright © 2015 John Wiley & Sons, Ltd.     

Raman spectroscopic study of the magnesium‐carbonate minerals—artinite and dypingite

Magnesium minerals are important in the understanding of the concept of geosequestration. The two hydrated hydroxy magnesium‐carbonate minerals artinite and dypingite were studied by Raman spectroscopy. Intense bands are observed at 1092 cm⁻¹ for artinite and at 1120 cm⁻¹ for dypingite, attributed ν₁ symmetric stretching mode of CO₃²⁻. The ν₃ antisymmetric stretching vibrations of CO₃²⁻ are extremely weak and are observed at 1412 and 1465 cm⁻¹ for artinite and at 1366, 1447 and 1524 cm⁻¹ for dypingite. Very weak Raman bands at 790 cm⁻¹ for artinite and 800 cm⁻¹ for dypingite are assigned to the CO₃²⁻ν₂ out‐of‐plane bend. The Raman band at 700 cm⁻¹ of artinite and at 725 and 760 cm⁻¹ of dypingite are ascribed to CO₃²⁻ν₂ in‐plane bending mode. The Raman spectrum of artinite in the OH stretching region is characterised by two sets of bands: (1) an intense band at 3593 cm⁻¹ assigned to the MgOH stretching vibrations and (2) the broad profile of overlapping bands at 3030 and 3229 cm⁻¹ attributed to water stretching vibrations. X‐ray diffraction studies show that the minerals are disordered. This is reflected in the difficulty of obtaining Raman spectra of reasonable quality, and explains why the Raman spectra of these minerals have not been previously or sufficiently described. Copyright © 2008 John Wiley & Sons, Ltd.     

Food additives characterization by infrared,Raman, and surface‐enhanced Raman spectroscopies

Fourier‐transform infrared (FT‐IR), Raman (RS), and surface‐enhanced Raman scattering (SERS) spectra of β‐hydroxy‐β‐methylobutanoic acid (HMB), L ‐carnitine, and N‐methylglycocyamine (creatine) have been measured. The SERS spectra have been taken from species adsorbed on a colloidal silver surface. The respective FT‐IR and RS band assignments (solid‐state samples) based on the literature data have been proposed. The strongest absorptions in the FT‐IR spectrum of creatine are observed at 1398, 1615, and 1699 cm⁻¹, which are due to ν_s(COOH) + ν(CN) + δ(CN), ρ_s(NH₂), and ν(C O) modes, respectively, whereas those of L ‐carnitine (at 1396/1586 cm⁻¹ and 1480 cm⁻¹) and HMB (at 1405/1555/1585 cm⁻¹ and 1437–1473 cm⁻¹) are associated with carboxyl and methyl/methylene group vibrations, respectively. On the other hand, the strongest bands in the RS spectrum of HMB observed at 748/1442/1462 cm⁻¹ and 1408 cm⁻¹ are due to methyl/methylene deformations and carboxyl group vibrations, respectively. The strongest Raman band of creatine at 831 cm⁻¹ (ρ_w(R NH₂)) is accompanied by two weaker bands at 1054 and 1397 cm⁻¹ due to ν(CN) + ν(R NH₂) and ν_s(COOH) + ν(CN) + δ(CN) modes, respectively. In the case of L ‐carnitine, its RS spectrum is dominated by bands at 772 and 1461 cm⁻¹ assigned to ρ_r(CH₂) and δ(CH₃), respectively. The analysis of the SERS spectra shows that HMB interacts with the silver surface mainly through the  COO⁻, hydroxyl, and  CH₂ groups, whereas L ‐carnitine binds to the surface via  COO⁻ and  N⁺(CH₃)₃ which is rarely enhanced at pH = 8.3. On the other hand, it seems that creatine binds weakly to the silver surface mainly by  NH₂, and C O from the  COO⁻ group. Copyright © 2006 John Wiley & Sons, Ltd.     

Determination of titanium content in pyrope by Raman spectroscopy

The titanium content of pyrope garnet can be quantified using the intensity of a Raman band at about 830 cm⁻¹ that is normalized to the 363 cm⁻¹ band using a spectrometer‐specific calibration using 10 to 15 chromian pyropes from Bohemia, Czech Republic. An accuracy of 0.025 wt% could be achieved for TiO₂ contents between 0.17 and 0.67 wt% TiO₂ with a Raman spectrometer with a spectral resolution of better than 3.9 cm⁻¹. The technique can be used in petrological and gemmological studies. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermo‐Raman spectroscopy of synthetic nesquehonite — implication for the geosequestration of greenhouse gases

Pure nesquehonite (MgCO₃·3H₂O)/Mg(HCO₃)(OH)·2H₂O was synthesised and characterised by a combination of thermo‐Raman spectroscopy and thermogravimetry with evolved gas analysis. Thermo‐Raman spectroscopy shows an intense band at 1098 cm⁻¹, which shifts to 1105 cm⁻¹ at 450 °C, assigned to the ν₁CO₃²⁻ symmetric stretching mode. Two bands at 1419 and 1509 cm⁻¹ assigned to the ν₃ antisymmetric stretching mode shift to 1434 and 1504 cm⁻¹ at 175 °C. Two new peaks at 1385 and 1405 cm⁻¹ observed at temperatures higher than 175 °C are assigned to the antisymmetric stretching modes of the (HCO₃)⁻ units. Throughout all the thermo‐Raman spectra, a band at 3550 cm⁻¹ is attributed to the stretching vibration of OH units. Raman bands at 3124, 3295 and 3423 cm⁻¹ are assigned to water stretching vibrations. The intensity of these bands is lost by 175 °C. The Raman spectra were in harmony with the thermal analysis data. This research has defined the thermal stability of one of the hydrous carbonates, namely nesquehonite. Thermo‐Raman spectroscopy enables the thermal stability of the mineral nesquehonite to be defined, and, further, the changes in the formula of nesquehonite with temperature change can be defined. Indeed, Raman spectroscopy enables the formula of nesquehonite to be better defined as Mg(OH)(HCO₃)·2H₂O. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman spectroscopic study of the antimonate mineral bottinoite Ni[Sb2(OH)12]·6H2O and in comparison with brandholzite Mg[Sb5+2(OH)12]·6H2O

Raman spectroscopy was used to study the mineral bottinoite and a comparison with the Raman spectra of brandholzite was made. An intense sharp Raman band at 618 cm⁻¹ is attributed to the SbO symmetric stretching mode. The low intensity band at 735 cm⁻¹ is ascribed to the SbO antisymmetric stretching vibration. Low intensity Raman bands were found at 501, 516 and 578 cm⁻¹. Four Raman bands observed at 1045, 1080, 1111 and 1163 cm⁻¹ are assigned to δ SbOH deformation modes. A complex pattern resulting from the overlapping band of the water and hydroxyl units is observed. Raman bands are observed at 3223, 3228, 3368, 3291, 3458 and 3510 cm⁻¹. The first two Raman bands are assigned to water stretching vibrations. The two higher wavenumber Raman bands observed at 3466 and 3552 cm⁻¹ and two infrared bands at 3434 and 3565 cm⁻¹ are assigned to the stretching vibrations of the hydroxyl units. Observed Raman and infrared bands are connected with O H···O hydrogen bonds and their lengths 2.72, 2.79, 2.86, 2.88 and 3.0 Å (Raman) and 2.73, 2.83 and 3.07 Å (infrared). Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of supplementary manganese on the sporulation of Bacillus endospores analysed by Raman spectroscopy

It is a common practice in microbiology to induce and accelerate sporulation of spore‐forming bacteria by adding small amounts of divalent manganese to the cultivation medium. By micro‐Raman spectroscopy the effect of supplementary divalent manganese during the growth and sporulation of Bacillus spp. bacteria was studied. The spectral alterations in the Raman spectra of single endospores due to this cultivation parameter comprised slight alterations of the bands attributed to intracellular, abundantly present calcium dipicolinate (CaDPA). Those signals suffered a loss of intensity or partial band broadening because of the appearance of new weak signals next to them. Exclusively in Raman spectra of single B. sphaericuss endospores, the band at 1485 cm⁻¹ vanished. The theoretical spectra of CaDPA and manganese dipicolinate (MnDPA) were calculated and compared with the experimental spectra to prove the hypothesis that, while the overall intracellular DPA content decreased, an intracellular assembly of MnDPA in the endospores might also occur. Band shifts of the COO⁻ vibrations in the salt's spectra as well as in the endospore's spectra, and the decrease of the two CaDPA bands, confirmed this proposal. The appearance of the 1030 cm⁻¹ band in all Bacillus spectra as well as the disappearance of the 1485 cm⁻¹ band in the B. sphaericus spectra still needs to be clarified. With the help of two multivariate chemometric methods, these spectral alterations allowed discrimination between single endospores of different Bacillus strains cultivated on normal nutrient agar (NA) and those grown on NA with MnSO₄ · xH₂O addition. With these investigations, a possible strategy is shown to trace back the cultivation environment of matured single endospores. Utilizing the joint concept of micro‐Raman spectroscopy and chemometric analysis, the differentiation between natively grown endospores and those cultivated in a laboratory with the help of manganous salts as a common sporulation accelerator seems accomplishable. Copyright © 2009 John Wiley & Sons, Ltd.     

Near‐infrared Raman spectroscopy for gastric precancer diagnosis

Raman spectroscopy is a molecular vibrational spectroscopic technique that is capable of optically probing the biomolecular changes associated with neoplastic transformation. The purpose of this study was to apply near‐infrared (NIR) Raman spectroscopy for differentiating dysplasia from normal gastric mucosa tissue. A total of 65 gastric mucosa tissues (44 normal and 21 dysplasia) were obtained from 35 patients who underwent endoscopy investigation or gastrectomy operation for this study. A rapid NIR Raman system was utilized for tissue Raman spectroscopic measurements at 785‐nm laser excitation. High‐quality Raman spectra in the range of 800–1800 cm⁻¹ can be acquired from gastric mucosa tissue within 5 s. Raman spectra showed significant differences between normal and dysplastic tissue, particularly in the spectral ranges of 850–1150, 1200–1500 and 1600–1750 cm⁻¹, which contained signals related to proteins, nucleic acids and lipids. The diagnostic decision algorithm based on the combination of Raman peak intensity ratios of I₈₇₅/I₁₄₅₀ and I₁₂₀₈/I₁₆₅₅ and the logistic regression analysis yielded a diagnostic sensitivity of 90.5% and specificity of 90.9% for identification of gastric dysplasia tissue. This work demonstrates that NIR Raman spectroscopy in conjunction with intensity ratio algorithms has the potential for the noninvasive diagnosis and detection of precancer in the stomach at the molecular level. Copyright © 2009 John Wiley & Sons, Ltd.     

Dussertite BaFe3+3(AsO4)2(OH)5—a Raman spectroscopic study of a hydroxy‐arsenate mineral

The mineral dussertite, a hydroxy‐arsenate mineral with formula BaFe³⁺₃(AsO₄)₂(OH)₅, has been studied by Raman spectroscopy complemented with infrared spectroscopy. The spectra of three minerals from different origins were investigated and proved to be quite similar, although some minor differences were observed. In the Raman spectra of the Czech dussertite, four bands are observed in the 800–950 cm⁻¹ region. The bands are assigned as follows: the band at 902 cm⁻¹ is assigned to the (AsO₄)³⁻ν₃ antisymmetric stretching mode, the one at 870 cm⁻¹ to the (AsO₄)³⁻ν₁ symmetric stretching mode, and those at 859 and 825 cm⁻¹ to the As‐OM^{2 + /3+} stretching modes and/or hydroxyl bending modes. Raman bands at 372 and 409 cm⁻¹ are attributed to the ν₂ (AsO₄)³⁻ bending mode and the two bands at 429 and 474 cm⁻¹ are assigned to the ν₄ (AsO₄)³⁻ bending mode. An intense band at 3446 cm⁻¹ in the infrared spectrum and a complex set of bands centred upon 3453 cm⁻¹ in the Raman spectrum are attributed to the stretching vibrations of the hydrogen‐bonded (OH)⁻ units and/or water units in the mineral structure. The broad infrared band at 3223 cm⁻¹ is assigned to the vibrations of hydrogen‐bonded water molecules. Raman spectroscopy identified Raman bands attributable to (AsO₄)³⁻ and (AsO₃OH)²⁻ units. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and Raman spectroscopic characterisation of the oxalate mineral wheatleyite Na2Cu2+(C2O4)2·2H2O

The mineral wheatleyite has been synthesised and characterised by Raman spectroscopy complimented with infrared spectroscopy. Two Raman bands at 1434 and 1470 cm⁻¹ are assigned to the ν_{(C O)} stretching mode and implies two independent oxalate anions. Two intense Raman bands observed at 904 and 860 cm⁻¹ are assigned to the ν(C C) stretching mode and support the concept of two non‐equivalent oxalate units in the wheatleyite structure. Two strong bands observed at 565 and 585 cm⁻¹ are assigned to the symmetric CCO in plane bending modes. The Raman band at 387 cm⁻¹ is attributed to the CuO stretching vibration and the bands at 127 and 173 cm⁻¹ to OCuO bending vibrations. A comparison is made with Raman spectra of selected natural oxalate bearing minerals. Oxalates are markers or indicators of environmental events. Oxalates are readily determined by Raman spectroscopy. Thus, deterioration of works of art, biogeochemical cycles, plant metal complexation, the presence of pigments and minerals formed in caves can be analysed. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman spectroscopy of the borosilicate mineral ferroaxinite

Raman spectroscopy, complemented by infrared spectroscopy, has been used to characterise the ferroaxinite minerals of the theoretical formula Ca₂Fe²⁺Al₂BSi₄O₁₅(OH), a ferrous aluminium borosilicate. The Raman spectra are complex but are subdivided into sections on the basis of the vibrating units. The Raman spectra are interpreted in terms of the addition of borate and silicate spectra. Three characteristic bands of ferroaxinite are observed at 1082, 1056 and 1025 cm⁻¹ and are attributed to BO₄ stretching vibrations. Bands at 1003, 991, 980 and 963 cm⁻¹ are assigned to SiO₄ stretching vibrations. Bands are found in these positions for each of the ferroaxinites studied. No Raman bands were found above 1100 cm⁻¹ showing that ferroaxinites contain only tetrahedral boron. The hydroxyl stretching region of ferroaxinites is characterised by a single Raman band between 3368 and 3376 cm⁻¹, the position of which is sample‐dependent. Bands for ferroaxinite at 678, 643, 618, 609, 588, 572, 546 cm⁻¹ may be attributed to the ν₄ bending modes and the three bands at 484, 444 and 428 cm⁻¹ may be attributed to the ν₂ bending modes of the (SiO₄)²⁻. Copyright © 2006 John Wiley & Sons, Ltd.