Infrared (IR) spectroscopy is widely used to identify molecular adsorbates that form on metals in... more Infrared (IR) spectroscopy is widely used to identify molecular adsorbates that form on metals in the course of surface chemical reactions. Because IR spectroscopy is one of the few surface-sensitive probes that provide molecule-specific information without perturbing the chemisorbed state, there is great interest in extracting as much structural information from the spectra as possible. The various ways IR spectroscopy is used to determine the structure of molecular adsorbates, from strictly qualitative interpretations based on symmetry selection rules to the use of ab initio electronic structure calculations to predict the IR spectrum of a chemisorbed molecule, are reviewed.
A de-waxing protocol that successfully removes paraffin from tissue microarray (TMA) cores of fix... more A de-waxing protocol that successfully removes paraffin from tissue microarray (TMA) cores of fixed tissue obtained from oral cancer is described.
BACKGROUND: Prostate cancer (CaP) preferentially metastasises to the bone, and we have previously... more BACKGROUND: Prostate cancer (CaP) preferentially metastasises to the bone, and we have previously shown that the poly-unsaturated fatty acid (PUFA) arachidonic acid (AA) is a potent stimulator of CaP invasion. Here we present that AA promotes CaP invasion by inducing bone marrow adipocyte formation. METHODS: Boyden invasion-chamber assays assessed the ability of dietary oils, their PUFA components, and specific PUFA-loaded adipocytes to induce PC-3 invasion. Lipid transfer and metabolism was followed using deuterated AA and Fourier Transform Infrared spectroscopy (FTIR). RESULTS: Poly-unsaturated fatty acid constituents, but not their corresponding dietary oils, induced PC-3 invasion. PUFAs induce bone marrow adipocyte (BM-Ad) differentiation with AA inducing higher levels of BM-Ad differentiation, as compared with other PUFAs (3998 ± 514.4 vs 932 ± 265.8; P ¼ 0.00002), which stimulated greater PC-3 invasion than free AA (22 408.5 ± 607.4 vs 16 236±313.9; P ¼ 0.01111) or adipocytes generated in the presence of other PUFAs. In bone marrow co-culture PC-3 and BM-Ad interactions result in direct uptake and metabolism of AA by PC-3 cells, destruction of the adipocyte and subsequent formation of a bone metastasis. CONCLUSION: The data supports the hypothesis that AA not only promotes CaP invasion, it also prepares the 'soil', making it more supportive for implantation and propagation of the migrating metastatic cell.
Cellulose microfibrils are the basic units of cellulose in plants. The structure of these microfi... more Cellulose microfibrils are the basic units of cellulose in plants. The structure of these microfibrils is at least partly determined by the structure of the cellulose synthase complex. In higher plants, this complex is composed of 18 to 24 catalytic subunits known as CELLULOSE SYNTHASE A (CESA) proteins. Three different classes of CESA proteins are required for cellulose synthesis and for secondary cell wall cellulose biosynthesis, which include CESA4, CESA7, and CESA8. To probe the relationship between CESA proteins and microfibril structure, we created mutant cesa proteins that lack catalytic activity but retain sufficient structural integrity to allow assembly of the cellulose synthase complex. Using a series of Arabidopsis mutants and genetic backgrounds, we found consistent differences in the ability of these mutant CESA proteins to complement the cellulose-deficient phenotype of the cesa null mutants. The best complementation was observed with catalytically inactive cesa4 whil...
Spectrochimica Acta Part A: Molecular Spectroscopy, 1990
The reflection-absorption infrared spectrum of cyclohexane adsorbed on Pt( 111) has been recorded... more The reflection-absorption infrared spectrum of cyclohexane adsorbed on Pt( 111) has been recorded using a Fourier Transform spectrometer. The spectrum at 150 K shows the broad, low-frequency CH stretching band previously revealed by electron energy loss spectroscopy and also three sharper bands attributed to vibrational modes involving the relatively unperturbed hydrogens. At 95 K a second adsorbed phase is formed in which the perturbation of the molecule is reduced. Continued exposure leads to multilayer formation. Spectra of adsorbed monolayers of the related compounds n-hexane, cyclopentane and 2,2_dimethylpropane (neopentane) showed much less evidence for perturbation of CH bonds.
The structure and reactivity of the surface methoxy species on Ag{ 11 l} have been studied using ... more The structure and reactivity of the surface methoxy species on Ag{ 11 l} have been studied using a combination of reflection absorption infrared spectroscopy and temperature-programmed desorption. Methoxy can be generated by exposing a preoxidized Ag{ 11 l} surface to methanol at 180 K and adsorbs in an upright geometry possessing effective 3-fold symmetry, with its C-0 bond axis oriented normal to the surface at all coverages. This conclusion is based on a detailed symmetry analysis coupled with rigorous application of the metalsurface selection rule and careful assignment of the infrared absorption bands with the aid of deuterium substitution. It is shown that strong Fermi resonance interactions are the cause behind unusual features observed in the C-H stretching region of the infrared spectra of methoxy on many metal surfaces. Significant interadsorbate dipole coupling and chemicaUelectrostatic effects are responsible for the coverage-dependent frequency shifts exhibited by the infrared active bands. Methoxy is stable on Ag{ 11 11 up to 290 K, above which it decomposes to yield formaldehyde as the major product, which desorbs in a reaction-limited step that is consistent with first-order kinetics. Formate has been identified as a minor surface species when excess surface oxygen is present and acts as the intermediate in the further oxidation of formaldehyde to COZ and Hz.
Material & Methods: For objectives (i-ii), mesenchymal stem cells were isolated from primary bone... more Material & Methods: For objectives (i-ii), mesenchymal stem cells were isolated from primary bone marrow tissue and differentiated into the adipocyte lineage. During adipogeneisis, preadipocytes were incubated with 50 μM D31-PA. Post adipocyte formation, these cells were incubated with serum-starved PC-3 cells for 48 hours and fixed. FTIR maps were collected at 6.25 μm pixel-resolution. For objective (ii), serum-starved PC-3 cells were fixed following 15, 30, 45, 60, 90, 120, 180 and 1440 minute exposures to 50 μM D31-PA. Results: Using the intensity of absorption for frequencies of the lipid υs(C-O) peak (1740-1718 cm-1), subcellular distributions of the triglycerol (TAG) and free FA deposits in FTIR maps of adipocytes were determined. Using the υ(C-D) signal of D31-PA and the υs+as(CH2+3) signal of non-isotopically labelled lipids, we found the %D31-PA incorporated into the adipocytes varied between adipocytes and was associated with its physical size. The υ(C-D) signal of D31-PA illuminated PC-3 cells in FTIR maps of PC-3-adipocyte co-cultures. Time-course experiments showed that uptake of 50 μM D31-PA into PC-3 cells was linearly correlated with time (R 2 = 0.87). Compared to control (cells with no D31-PA) a significant (p≤0.05) increase in endogenous lipids in the D31-PA exposed cells may be the result of a cell-rescue response to the cytotoxic effects of D31-PA that is inhibited through D31-PA channelling into TAG pools. Conclusions: These preliminary results demonstrate the use of FTIR technology to probe (i) subcellular fatty acid transport, (ii) uptake of specific FAs without lipid extraction and (iii) determine the metabolic consequences of FA intake in a time-resolved manner.
Infrared reflection absorption spectroscopy together with mass spectrometry has been used to inve... more Infrared reflection absorption spectroscopy together with mass spectrometry has been used to investigate the interaction of NO and CO on Pt{1 0 0}, initially prepared in the reconstructed ÔhexÕ phase, under ambient pressures of these gases, in the temperature range 300-500 K. The results allow the local and total coverages of adsorbed CO and NO to be related to the rate of reaction to produce gas phase CO 2 , and provide insight into the species present on the surface during the so-called low temperature oscillatory reaction regime of this process. At temperatures below that at which NO dissociation occurs (approximately 390-400 K) adsorption is controlled by the non-reactive displacement of NO by CO and results in a CO-poisoned surface. Above 400 K when significant CO 2 production occurs, the NO coverage increases to produce a surface with NO and CO fully intermixed; the increase in NO coverage is attributed to the higher rate of NO arrival from the gas phase (with a partial pressure ratio of P NO :P CO > 1) at free surface sites created by NO dissociation and subsequent reaction with CO. The competition between these two processes of nonreactive NO displacement by CO and reactive displacement of CO by NO is proposed to determine the parameter space of the low temperature oscillatory regime. Rapid equilibration between bridged and atop CO species leads to them appearing to exhibit identical reaction behaviour. Particularly at the lowest reaction temperatures (around 400 K), islands of pure CO may coexist on the surface but not participate in the reaction. Under conditions corresponding to the high temperature oscillatory regime, small quantities of absorbed CO, but no NO, are seen on the surface.
Here we report on investigations into using Raman optical tweezers to analyse both live and chemi... more Here we report on investigations into using Raman optical tweezers to analyse both live and chemically fixed prostate and bladder cells. Spectra were subjected to chemometric analysis to discriminate and classify the cell types based on their spectra. Subsequent results revealed the potential of Raman tweezers as a potential clinical diagnostic tool.
The adsorption and reaction of the surface formate species on Ag{111} have been studied using a c... more The adsorption and reaction of the surface formate species on Ag{111} have been studied using a combination of reflection absorption infrared spectroscopy and temperature programmed desorption. Four formate species with distinct bonding configurations have been identified when formic acid is deprotonated by preoxidized Ag{111} at 240 K. Bidentate bridging formate with 2-fold symmetry is present at low coverage, while monodentate formate with three different degrees of tilt are formed sequentially with increasing coverage as a result of dipolar interactions and steric crowding. Coadsorption of methoxy and formate, accomplished by nucleophilic displacement of methyl formate with surface atomic O, yields an intermixed surface phase where interadsorbate interactions are minimized and formate tilting is suppressed. Monodentate formate partially decomposes to CO 2 and formic acid at 325 K and partially reverts to bidentate bridging formate which dehydrogenates at 350 K to give CO 2 and H 2 .
ABSTRACT When Ag{111} is exposed to NO at 40 K, monolayer adsorption is followed by multilayer (N... more ABSTRACT When Ag{111} is exposed to NO at 40 K, monolayer adsorption is followed by multilayer (NO)(2) formation. Heating to 60 K results in the desorption of the dimer multilayer, leaving a monolayer on the surface. Using isotopes, the monolayer has also been characterized as dimers, which have the N-N axis coplanar with the surface. At 70 to 90 K, N2O is formed from (NO)(2) on the Ag{111} surface. Further heating to 120 K results in the desorption of the N2O. The reactive species is thus shown to be the adsorbed dimer, which cannot be formed at higher temperatures on exposure to NO because the surface coverage is too low. The monomer, adsorbed NO, is thus weakly adsorbed, in agreement with expectation.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology, Jan 20, 2013
459 Background: In contrast to standard pathology, where stained cells and tissues are examined v... more 459 Background: In contrast to standard pathology, where stained cells and tissues are examined visually under a microscope, spectral pathology is the study of changes in cellular composition of unstained tissue using molecular fingerprint techniques, such as infrared and Raman spectroscopy. Hyperspectral images are collected which provide not only spatial information but also data of high dimensionality, probing the global biochemistry of the biological specimen in the mid-infrared range. 9 paraffin-embedded, formalin-fixed clear cell renal carcinoma tissue sections (8μm thick) of different grade, stage and with respective matched pairs, were floated onto infrared-transmitting substrates. After dewaxing, Fourier transform infrared imaging spectroscopy was performed on a Varian 670-IR spectrometer coupled with a Varian 620-IR imaging microscope (Agilent Technologies, CA) equipped with a 128×128 pixel Mercury-Cadmium-Telluride focal planar array detector. A hyperspectral image is obt...
Synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy has been applied to the ... more Synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy has been applied to the study of dynamic cellular events. SR-FTIR microspectroscopy is a powerful bioanalytical technique for the simultaneous analysis of proteins, lipids and a variety of phosphorylated molecules within whole cells. In this study, SR-FTIR microspectroscopy was used in imaging mode to generate biospectroscopic chemical maps of formalin-fixed PC-3 prostate cancer cells, which had been preserved in the process of cell division (cytokinesis) and locomotion. The distribution and intensity profiles of IR signals corresponding to the amide I and II (protein) and/or n as and s (CH 3 ), n as and s (CH 2 ) (lipid) modes were found to be useful in understanding fundamental biochemical processes at the midbody of the cytokinetic cells and at the lamellipodium of motile cells. Furthermore, in both of these cellular systems we observed a distinct hemispherical distribution of the lipid ester (C O) signal, which surrounded high phosphate signal. This feature was assigned to intracellular IR signals corresponding to membrane-rich organelles surrounding the cell nucleus.
Raman Tweezers is a technique that combines optical trapping with Raman spectroscopy and has enab... more Raman Tweezers is a technique that combines optical trapping with Raman spectroscopy and has enabled the spectroscopic analysis of single cells. Applications of this technique include the identification and discrimination of different types of cells, including healthy and non-healthy cells (e.g. cancer cells). In addition, the interaction of cells with stimuli, e.g. drugs, can also be studied on a single-cell basis. Herein, a generic protocol for the analysis of fixed and living single eukaryotic cells is described, including the considerations required to build a Raman Tweezers systems.
The adsorption of ammonia (NH3) on the NiI 111) surface has been investigated by photoelectron di... more The adsorption of ammonia (NH3) on the NiI 111) surface has been investigated by photoelectron diffraction. To determine the adsorption site and the distance above the NiI 111] surface, photoelectron diffraction spectra of the N 1s core level were recorded in the scanned energy mode for normal and two off-normal emission directions and compared with extensive multiple-scattering calculations. The best 0 agreement and the lowest 8 factor were found for an atop site and a Ni-N bond length of 1.97 A. The anisotropic vibrations of the emitter have been taken into account in the theory and the mean-square displacement for the vibrations of the ammonia molecule parallel to the surface was determined to be 0.04 A.
2007 Joint 32nd International Conference on Infrared and Millimeter Waves and the 15th International Conference on Terahertz Electronics, 2007
ABSTRACT There is a general interest in developing a new research field linking new powerful sour... more ABSTRACT There is a general interest in developing a new research field linking new powerful sources of THz radiation with key contemporary challenges in protein science; Specifically, the highly controversial role of fast protein promoting vibrations in biological catalysis. However, the 1-10 THz region of the electromagnetic spectrum is particularly difficult to access experimentally due to the low intensity of conventional laboratory based sources. Therefore we developed a THz radiation station using the existing accelerator based sources on the SRS at Daresbury. We recorded spectra incorporating the low frequency collective vibrations of small molecules as well as some proteins in the solid state. Our experiments were carried out using non-coherent radiation from the modified THz testing facility (TTF) on the SRS at Daresbury.
Integrative biology : quantitative biosciences from nano to macro, 2009
In this review the recent emergence of Raman tweezers as an analytical technique for single eukar... more In this review the recent emergence of Raman tweezers as an analytical technique for single eukaryotic cell analysis is described. The Raman tweezer technique combines Raman spectroscopy as a diagnostic tool with optical tweezers by which means single cells can be trapped and manipulated in a laser beam using a high numerical aperture imaging microscope. Necessary instrumental requirements to facilitate Raman tweezer experiments are discussed together with practical considerations such as the potential for photodamage of cells subjected to trapping and Raman excitation. Specific applications of Raman tweezers to the analysis of cancer cells, erythrocytes and lymphocytes, micro-organisms and sub-cellular components e.g.chromosomes and mitochondria are then discussed followed by a summary of the future potential of the technique for single cell analysis.
The technique of infrared reflection-absorption spectroscopy (IRAS) is characterised by an intrin... more The technique of infrared reflection-absorption spectroscopy (IRAS) is characterised by an intrinsically high spectral resolution which can be used to full advantage in adsorbate lineshape studies as well as in the investigation of lateral interactions, phase transitions, island growth processes and co-adsorption effects. We illustrate some of these applications in recent studies of the metal-carbon stretch in the system Pt{111}-CO and of the C-O stretch in the system Pt{111}-CO/K.
Journal of the Chemical Society, Faraday Transactions, 1995
Adsorption of Nitric Oxide on lr(lO0): Influence of Substrate Reconstruction ... P. Gardner,? R. ... more Adsorption of Nitric Oxide on lr(lO0): Influence of Substrate Reconstruction ... P. Gardner,? R. Martin, R. Nalerinski, CLA Lamorit,$ MJ Weaver$ and AM Bradshaw" Fritz-Haber-lnstitut der Max-Planck-Gesellschafi, Faradayweg 44, 14 195 Berlin, Germany
Infrared (IR) spectroscopy is widely used to identify molecular adsorbates that form on metals in... more Infrared (IR) spectroscopy is widely used to identify molecular adsorbates that form on metals in the course of surface chemical reactions. Because IR spectroscopy is one of the few surface-sensitive probes that provide molecule-specific information without perturbing the chemisorbed state, there is great interest in extracting as much structural information from the spectra as possible. The various ways IR spectroscopy is used to determine the structure of molecular adsorbates, from strictly qualitative interpretations based on symmetry selection rules to the use of ab initio electronic structure calculations to predict the IR spectrum of a chemisorbed molecule, are reviewed.
A de-waxing protocol that successfully removes paraffin from tissue microarray (TMA) cores of fix... more A de-waxing protocol that successfully removes paraffin from tissue microarray (TMA) cores of fixed tissue obtained from oral cancer is described.
BACKGROUND: Prostate cancer (CaP) preferentially metastasises to the bone, and we have previously... more BACKGROUND: Prostate cancer (CaP) preferentially metastasises to the bone, and we have previously shown that the poly-unsaturated fatty acid (PUFA) arachidonic acid (AA) is a potent stimulator of CaP invasion. Here we present that AA promotes CaP invasion by inducing bone marrow adipocyte formation. METHODS: Boyden invasion-chamber assays assessed the ability of dietary oils, their PUFA components, and specific PUFA-loaded adipocytes to induce PC-3 invasion. Lipid transfer and metabolism was followed using deuterated AA and Fourier Transform Infrared spectroscopy (FTIR). RESULTS: Poly-unsaturated fatty acid constituents, but not their corresponding dietary oils, induced PC-3 invasion. PUFAs induce bone marrow adipocyte (BM-Ad) differentiation with AA inducing higher levels of BM-Ad differentiation, as compared with other PUFAs (3998 ± 514.4 vs 932 ± 265.8; P ¼ 0.00002), which stimulated greater PC-3 invasion than free AA (22 408.5 ± 607.4 vs 16 236±313.9; P ¼ 0.01111) or adipocytes generated in the presence of other PUFAs. In bone marrow co-culture PC-3 and BM-Ad interactions result in direct uptake and metabolism of AA by PC-3 cells, destruction of the adipocyte and subsequent formation of a bone metastasis. CONCLUSION: The data supports the hypothesis that AA not only promotes CaP invasion, it also prepares the 'soil', making it more supportive for implantation and propagation of the migrating metastatic cell.
Cellulose microfibrils are the basic units of cellulose in plants. The structure of these microfi... more Cellulose microfibrils are the basic units of cellulose in plants. The structure of these microfibrils is at least partly determined by the structure of the cellulose synthase complex. In higher plants, this complex is composed of 18 to 24 catalytic subunits known as CELLULOSE SYNTHASE A (CESA) proteins. Three different classes of CESA proteins are required for cellulose synthesis and for secondary cell wall cellulose biosynthesis, which include CESA4, CESA7, and CESA8. To probe the relationship between CESA proteins and microfibril structure, we created mutant cesa proteins that lack catalytic activity but retain sufficient structural integrity to allow assembly of the cellulose synthase complex. Using a series of Arabidopsis mutants and genetic backgrounds, we found consistent differences in the ability of these mutant CESA proteins to complement the cellulose-deficient phenotype of the cesa null mutants. The best complementation was observed with catalytically inactive cesa4 whil...
Spectrochimica Acta Part A: Molecular Spectroscopy, 1990
The reflection-absorption infrared spectrum of cyclohexane adsorbed on Pt( 111) has been recorded... more The reflection-absorption infrared spectrum of cyclohexane adsorbed on Pt( 111) has been recorded using a Fourier Transform spectrometer. The spectrum at 150 K shows the broad, low-frequency CH stretching band previously revealed by electron energy loss spectroscopy and also three sharper bands attributed to vibrational modes involving the relatively unperturbed hydrogens. At 95 K a second adsorbed phase is formed in which the perturbation of the molecule is reduced. Continued exposure leads to multilayer formation. Spectra of adsorbed monolayers of the related compounds n-hexane, cyclopentane and 2,2_dimethylpropane (neopentane) showed much less evidence for perturbation of CH bonds.
The structure and reactivity of the surface methoxy species on Ag{ 11 l} have been studied using ... more The structure and reactivity of the surface methoxy species on Ag{ 11 l} have been studied using a combination of reflection absorption infrared spectroscopy and temperature-programmed desorption. Methoxy can be generated by exposing a preoxidized Ag{ 11 l} surface to methanol at 180 K and adsorbs in an upright geometry possessing effective 3-fold symmetry, with its C-0 bond axis oriented normal to the surface at all coverages. This conclusion is based on a detailed symmetry analysis coupled with rigorous application of the metalsurface selection rule and careful assignment of the infrared absorption bands with the aid of deuterium substitution. It is shown that strong Fermi resonance interactions are the cause behind unusual features observed in the C-H stretching region of the infrared spectra of methoxy on many metal surfaces. Significant interadsorbate dipole coupling and chemicaUelectrostatic effects are responsible for the coverage-dependent frequency shifts exhibited by the infrared active bands. Methoxy is stable on Ag{ 11 11 up to 290 K, above which it decomposes to yield formaldehyde as the major product, which desorbs in a reaction-limited step that is consistent with first-order kinetics. Formate has been identified as a minor surface species when excess surface oxygen is present and acts as the intermediate in the further oxidation of formaldehyde to COZ and Hz.
Material & Methods: For objectives (i-ii), mesenchymal stem cells were isolated from primary bone... more Material & Methods: For objectives (i-ii), mesenchymal stem cells were isolated from primary bone marrow tissue and differentiated into the adipocyte lineage. During adipogeneisis, preadipocytes were incubated with 50 μM D31-PA. Post adipocyte formation, these cells were incubated with serum-starved PC-3 cells for 48 hours and fixed. FTIR maps were collected at 6.25 μm pixel-resolution. For objective (ii), serum-starved PC-3 cells were fixed following 15, 30, 45, 60, 90, 120, 180 and 1440 minute exposures to 50 μM D31-PA. Results: Using the intensity of absorption for frequencies of the lipid υs(C-O) peak (1740-1718 cm-1), subcellular distributions of the triglycerol (TAG) and free FA deposits in FTIR maps of adipocytes were determined. Using the υ(C-D) signal of D31-PA and the υs+as(CH2+3) signal of non-isotopically labelled lipids, we found the %D31-PA incorporated into the adipocytes varied between adipocytes and was associated with its physical size. The υ(C-D) signal of D31-PA illuminated PC-3 cells in FTIR maps of PC-3-adipocyte co-cultures. Time-course experiments showed that uptake of 50 μM D31-PA into PC-3 cells was linearly correlated with time (R 2 = 0.87). Compared to control (cells with no D31-PA) a significant (p≤0.05) increase in endogenous lipids in the D31-PA exposed cells may be the result of a cell-rescue response to the cytotoxic effects of D31-PA that is inhibited through D31-PA channelling into TAG pools. Conclusions: These preliminary results demonstrate the use of FTIR technology to probe (i) subcellular fatty acid transport, (ii) uptake of specific FAs without lipid extraction and (iii) determine the metabolic consequences of FA intake in a time-resolved manner.
Infrared reflection absorption spectroscopy together with mass spectrometry has been used to inve... more Infrared reflection absorption spectroscopy together with mass spectrometry has been used to investigate the interaction of NO and CO on Pt{1 0 0}, initially prepared in the reconstructed ÔhexÕ phase, under ambient pressures of these gases, in the temperature range 300-500 K. The results allow the local and total coverages of adsorbed CO and NO to be related to the rate of reaction to produce gas phase CO 2 , and provide insight into the species present on the surface during the so-called low temperature oscillatory reaction regime of this process. At temperatures below that at which NO dissociation occurs (approximately 390-400 K) adsorption is controlled by the non-reactive displacement of NO by CO and results in a CO-poisoned surface. Above 400 K when significant CO 2 production occurs, the NO coverage increases to produce a surface with NO and CO fully intermixed; the increase in NO coverage is attributed to the higher rate of NO arrival from the gas phase (with a partial pressure ratio of P NO :P CO > 1) at free surface sites created by NO dissociation and subsequent reaction with CO. The competition between these two processes of nonreactive NO displacement by CO and reactive displacement of CO by NO is proposed to determine the parameter space of the low temperature oscillatory regime. Rapid equilibration between bridged and atop CO species leads to them appearing to exhibit identical reaction behaviour. Particularly at the lowest reaction temperatures (around 400 K), islands of pure CO may coexist on the surface but not participate in the reaction. Under conditions corresponding to the high temperature oscillatory regime, small quantities of absorbed CO, but no NO, are seen on the surface.
Here we report on investigations into using Raman optical tweezers to analyse both live and chemi... more Here we report on investigations into using Raman optical tweezers to analyse both live and chemically fixed prostate and bladder cells. Spectra were subjected to chemometric analysis to discriminate and classify the cell types based on their spectra. Subsequent results revealed the potential of Raman tweezers as a potential clinical diagnostic tool.
The adsorption and reaction of the surface formate species on Ag{111} have been studied using a c... more The adsorption and reaction of the surface formate species on Ag{111} have been studied using a combination of reflection absorption infrared spectroscopy and temperature programmed desorption. Four formate species with distinct bonding configurations have been identified when formic acid is deprotonated by preoxidized Ag{111} at 240 K. Bidentate bridging formate with 2-fold symmetry is present at low coverage, while monodentate formate with three different degrees of tilt are formed sequentially with increasing coverage as a result of dipolar interactions and steric crowding. Coadsorption of methoxy and formate, accomplished by nucleophilic displacement of methyl formate with surface atomic O, yields an intermixed surface phase where interadsorbate interactions are minimized and formate tilting is suppressed. Monodentate formate partially decomposes to CO 2 and formic acid at 325 K and partially reverts to bidentate bridging formate which dehydrogenates at 350 K to give CO 2 and H 2 .
ABSTRACT When Ag{111} is exposed to NO at 40 K, monolayer adsorption is followed by multilayer (N... more ABSTRACT When Ag{111} is exposed to NO at 40 K, monolayer adsorption is followed by multilayer (NO)(2) formation. Heating to 60 K results in the desorption of the dimer multilayer, leaving a monolayer on the surface. Using isotopes, the monolayer has also been characterized as dimers, which have the N-N axis coplanar with the surface. At 70 to 90 K, N2O is formed from (NO)(2) on the Ag{111} surface. Further heating to 120 K results in the desorption of the N2O. The reactive species is thus shown to be the adsorbed dimer, which cannot be formed at higher temperatures on exposure to NO because the surface coverage is too low. The monomer, adsorbed NO, is thus weakly adsorbed, in agreement with expectation.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology, Jan 20, 2013
459 Background: In contrast to standard pathology, where stained cells and tissues are examined v... more 459 Background: In contrast to standard pathology, where stained cells and tissues are examined visually under a microscope, spectral pathology is the study of changes in cellular composition of unstained tissue using molecular fingerprint techniques, such as infrared and Raman spectroscopy. Hyperspectral images are collected which provide not only spatial information but also data of high dimensionality, probing the global biochemistry of the biological specimen in the mid-infrared range. 9 paraffin-embedded, formalin-fixed clear cell renal carcinoma tissue sections (8μm thick) of different grade, stage and with respective matched pairs, were floated onto infrared-transmitting substrates. After dewaxing, Fourier transform infrared imaging spectroscopy was performed on a Varian 670-IR spectrometer coupled with a Varian 620-IR imaging microscope (Agilent Technologies, CA) equipped with a 128×128 pixel Mercury-Cadmium-Telluride focal planar array detector. A hyperspectral image is obt...
Synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy has been applied to the ... more Synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy has been applied to the study of dynamic cellular events. SR-FTIR microspectroscopy is a powerful bioanalytical technique for the simultaneous analysis of proteins, lipids and a variety of phosphorylated molecules within whole cells. In this study, SR-FTIR microspectroscopy was used in imaging mode to generate biospectroscopic chemical maps of formalin-fixed PC-3 prostate cancer cells, which had been preserved in the process of cell division (cytokinesis) and locomotion. The distribution and intensity profiles of IR signals corresponding to the amide I and II (protein) and/or n as and s (CH 3 ), n as and s (CH 2 ) (lipid) modes were found to be useful in understanding fundamental biochemical processes at the midbody of the cytokinetic cells and at the lamellipodium of motile cells. Furthermore, in both of these cellular systems we observed a distinct hemispherical distribution of the lipid ester (C O) signal, which surrounded high phosphate signal. This feature was assigned to intracellular IR signals corresponding to membrane-rich organelles surrounding the cell nucleus.
Raman Tweezers is a technique that combines optical trapping with Raman spectroscopy and has enab... more Raman Tweezers is a technique that combines optical trapping with Raman spectroscopy and has enabled the spectroscopic analysis of single cells. Applications of this technique include the identification and discrimination of different types of cells, including healthy and non-healthy cells (e.g. cancer cells). In addition, the interaction of cells with stimuli, e.g. drugs, can also be studied on a single-cell basis. Herein, a generic protocol for the analysis of fixed and living single eukaryotic cells is described, including the considerations required to build a Raman Tweezers systems.
The adsorption of ammonia (NH3) on the NiI 111) surface has been investigated by photoelectron di... more The adsorption of ammonia (NH3) on the NiI 111) surface has been investigated by photoelectron diffraction. To determine the adsorption site and the distance above the NiI 111] surface, photoelectron diffraction spectra of the N 1s core level were recorded in the scanned energy mode for normal and two off-normal emission directions and compared with extensive multiple-scattering calculations. The best 0 agreement and the lowest 8 factor were found for an atop site and a Ni-N bond length of 1.97 A. The anisotropic vibrations of the emitter have been taken into account in the theory and the mean-square displacement for the vibrations of the ammonia molecule parallel to the surface was determined to be 0.04 A.
2007 Joint 32nd International Conference on Infrared and Millimeter Waves and the 15th International Conference on Terahertz Electronics, 2007
ABSTRACT There is a general interest in developing a new research field linking new powerful sour... more ABSTRACT There is a general interest in developing a new research field linking new powerful sources of THz radiation with key contemporary challenges in protein science; Specifically, the highly controversial role of fast protein promoting vibrations in biological catalysis. However, the 1-10 THz region of the electromagnetic spectrum is particularly difficult to access experimentally due to the low intensity of conventional laboratory based sources. Therefore we developed a THz radiation station using the existing accelerator based sources on the SRS at Daresbury. We recorded spectra incorporating the low frequency collective vibrations of small molecules as well as some proteins in the solid state. Our experiments were carried out using non-coherent radiation from the modified THz testing facility (TTF) on the SRS at Daresbury.
Integrative biology : quantitative biosciences from nano to macro, 2009
In this review the recent emergence of Raman tweezers as an analytical technique for single eukar... more In this review the recent emergence of Raman tweezers as an analytical technique for single eukaryotic cell analysis is described. The Raman tweezer technique combines Raman spectroscopy as a diagnostic tool with optical tweezers by which means single cells can be trapped and manipulated in a laser beam using a high numerical aperture imaging microscope. Necessary instrumental requirements to facilitate Raman tweezer experiments are discussed together with practical considerations such as the potential for photodamage of cells subjected to trapping and Raman excitation. Specific applications of Raman tweezers to the analysis of cancer cells, erythrocytes and lymphocytes, micro-organisms and sub-cellular components e.g.chromosomes and mitochondria are then discussed followed by a summary of the future potential of the technique for single cell analysis.
The technique of infrared reflection-absorption spectroscopy (IRAS) is characterised by an intrin... more The technique of infrared reflection-absorption spectroscopy (IRAS) is characterised by an intrinsically high spectral resolution which can be used to full advantage in adsorbate lineshape studies as well as in the investigation of lateral interactions, phase transitions, island growth processes and co-adsorption effects. We illustrate some of these applications in recent studies of the metal-carbon stretch in the system Pt{111}-CO and of the C-O stretch in the system Pt{111}-CO/K.
Journal of the Chemical Society, Faraday Transactions, 1995
Adsorption of Nitric Oxide on lr(lO0): Influence of Substrate Reconstruction ... P. Gardner,? R. ... more Adsorption of Nitric Oxide on lr(lO0): Influence of Substrate Reconstruction ... P. Gardner,? R. Martin, R. Nalerinski, CLA Lamorit,$ MJ Weaver$ and AM Bradshaw" Fritz-Haber-lnstitut der Max-Planck-Gesellschafi, Faradayweg 44, 14 195 Berlin, Germany
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Papers by Peter Gardner