Synchrotron-based Fourier Transform Infrared Research Articles

Synergistic Enhancement of Targeted Wound Healing by Near-Infrared Photodynamic Therapy and Silver Metal-Organic Frameworks Combined with S- or N-Doped Carbon Dots.

The literature data emphasize that nanoparticles might improve the beneficial effects of near-infrared light (NIR) on wound healing. This study investigates the mechanisms of the synergistic wound healing potential of NIR light and silver metal-organic frameworks combined with nitrogen- and sulfur-doped carbon dots (AgMOFsN-CDs and AgMOFsS-CDs, respectively), which was conducted by testing the fibroblasts viability, scratch assays, biochemical analysis, and synchrotron-based Fourier transform infrared (SR-FTIR) cell spectroscopy and imaging. Our findings reveal that the combined treatment of AgMOFsN-CDs and NIR light significantly increases cell viability to nearly 150% and promotes cell proliferation, with reduced interleukin-1 levels, suggesting an anti-inflammatory response. SR-FTIR spectroscopy shows this combined treatment results in unique protein alterations, including increased α-helix structures and reduced cross-β. Additionally, protein synthesis was enhanced upon the combined treatment. The likely mechanism behind the observed changes is the charge-specific interaction of N-CDs from the AgMOFsN-CDs with proteins, enhanced by NIR light due to the nanocomposite's optical characteristics. Remarkably, the complete wound closure in the in vitro scratch assay was achieved exclusively with the combined NIR and AgMOFsN-CDs treatment, demonstrating the promising application of combined AgMOFsN-CDs with NIR light photodynamic therapy in regenerative nanomedicine and tissue engineering.

Multifunctionalized Carbon Dots as an Active Nanocarrier for Drug Delivery to the Glioblastoma Cell Line.

Nanoparticle-based nanocarriers represent a viable alternative to conventional direct administration in cancer cells. This advanced approach employs the use of nanotechnology to transport therapeutic agents directly to cancer cells, thereby reducing the risk of damage to healthy cells and enhancing the efficacy of treatment. By approving nanoparticle-based nanocarriers, the potential for targeted, effective treatment is greatly increased. The so-called carbon-based nanoparticles, or carbon dots, have been hydrothermally prepared and initiated by a polymerization process. We synthesized and characterized nanoparticles of 2-acrylamido-2-methylpropanesulfonic acid, which showed biocompatibility with glioblastoma cells, and further, we tested them as a carrier for the drug riluzole. The obtained nanoparticles have been extensively characterized by techniques to obtain the exact composition of their surface by using Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (NMR) spectroscopy, as well as cryo-transmission electron microscopy. We found that the surface of the synthesized nanoparticles (NPs) is covered mainly by sulfonated, carboxylic, and substituted amide groups. These functional groups make them suitable as carriers for drug delivery in cancer cells. Specifically, we have successfully utilized the NPs as a delivery system for the drug riluzole, which has shown efficacy in treating glioblastoma cancer cells. The effect of nanoparticles as carriers for the riluzole system on glioblastoma cells was studied using live-cell synchrotron-based FTIR microspectroscopy to monitor in situ biochemical changes. After applying nanoparticles as nanocarriers, we have observed changes in all biomacromolecules, including the nucleic acids and protein conformation. These findings provide a strong foundation for further exploration into the development of targeted treatments for glioblastoma.

Arbuscular Mycorrhizal Fungi Drive Organo-Mineral Association in Iron Ore Tailings: Unravelling Microstructure at the Submicron Scale by Synchrotron-Based FTIR and STXM-NEXAFS.

Arbuscular mycorrhizal (AM) fungi play an important role in organic matter (OM) stabilization in Fe ore tailings for eco-engineered soil formation. However, little has been understood about the AM fungi-derived organic signature and organo-mineral interactions in situ at the submicron scale. In this study, a compartmentalized cultivation system was used to investigate the role of AM fungi in OM formation and stabilization in tailings. Particularly, microspectroscopic analyses including synchrotron-based transmission Fourier transform infrared (FTIR) and scanning transmission X-ray microspectroscopy combined with near-edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS) were employed to characterize the chemical signatures at the AM fungal-mineral and mineral-OM interfaces at the submicron scale. The results indicated that AM fungal mycelia developed well in the tailings and entangled mineral particles for aggregation. AM fungal colonization enhanced N-rich OM stabilization through organo-mineral association. Bulk spectroscopic analysis together with FTIR mapping revealed that fungi-derived lipids, proteins, and carbohydrates were associated with Fe/Si minerals. Furthermore, STXM-NEXAFS analysis revealed that AM fungi-derived aromatic, aliphatic, and carboxylic/amide compounds were heterogeneously distributed and trapped by Fe(II)/Fe(III)-bearing minerals originating from biotite-like minerals weathering. These findings imply that AM fungi can stimulate mineral weathering and provide organic substances to associate with minerals, contributing to OM stabilization and aggregate formation as key processes for eco-engineered soil formation in tailings.

Exploring the cellular surface polysaccharide and root nodule symbiosis characteristics of the rpoN mutants of Bradyrhizobium sp. DOA9 using synchrotron-based Fourier transform infrared microspectroscopy in conjunction with X-ray absorption spectroscopy.

The functional significance of rpoN genes that encode two sigma factors in the Bradyrhizobium sp. strain DOA9 has been reported to affect colony formation, root nodulation characteristics, and symbiotic interactions with Aeschynomene americana. rpoN mutant strains are defective in cellular surface polysaccharide (CSP) production compared with the wild-type (WT) strain, and they accordingly exhibit smaller colonies and diminished symbiotic effectiveness. To gain deeper insights into the changes in CSP composition and the nodules of rpoN mutants, we employed synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy and X-ray absorption spectroscopy. FTIR analysis of the CSP revealed the absence of specific components in the rpoN mutants, including lipids, carboxylic groups, polysaccharide-pyranose rings, and β-galactopyranosyl residues. Nodules formed by DOA9WT exhibited a uniform distribution of lipids, proteins, and carbohydrates; mutant strains, particularly DOA9∆rpoNp:ΩrpoNc, exhibited decreased distribution uniformity and a lower concentration of C=O groups. Furthermore, Fe K-edge X-ray absorption near-edge structure and extended X-ray absorption fine structure analyses revealed deficiencies in the nitrogenase enzyme in the nodules of DOA9∆rpoNc and DOA9∆rpoNp:ΩrpoNc mutants; nodules from DOA9WT and DOA9∆rpoNp exhibited both leghemoglobin and the nitrogenase enzyme. IMPORTANCE This work provides valuable insights into how two rpoN genes affect the composition of cellular surface polysaccharides (CSPs) in Bradyrhizobium sp., which subsequently dictates root nodule chemical characteristics and nitrogenase production. We used advanced synchrotron methods, including synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy and X-ray absorption spectroscopy (XAS), for the first time in this field to analyze CSP components and reveal the biochemical changes occurring within nodules. These cutting-edge techniques confer significant advantages by providing detailed molecular information, enabling the identification of specific functional groups, chemical bonds, and biomolecule changes. This research not only contributes to our understanding of plant-microbe interactions but also establishes a foundation for future investigations and potential applications in this field. The combined use of the synchrotron-based FTIR and XAS techniques represents a significant advancement in facilitating a comprehensive exploration of bacterial CSPs and their implications in plant-microbe interactions.

Synchrotron-based FTIR microspectroscopy reveals DNA methylation profile in DNA-HALO structure

Fourier transform infrared (FTIR) spectroscopy is a rapid, non-destructive and label-free technique for identifying subtle changes in all bio-macromolecules, and has been used as a method of choice for studying DNA conformation, secondary DNA structure transition and DNA damage. In addition, the specific level of chromatin complexity is introduced via epigenetic modifications forcing the technological upgrade in the analysis of such an intricacy. As the most studied epigenetic mechanism, DNA methylation is a major regulator of transcriptional activity, involved in the suppression of a broad spectrum of genes and its deregulation is involved in all non-communicable diseases. The present study was designed to explore the use of synchrotron-based FTIR analysis to monitor the subtle changes in molecule bases regarding the DNA methylation status of cytosine in the whole genome. In order to reveal the conformation-related best sample for FTIR-based DNA methylation analysis in situ, we used methodology for nuclear HALO preparations and slightly modified it to isolated DNA in HALO formations. Nuclear DNA-HALOs represent samples with preserved higher-order chromatin structure liberated of any protein residues that are closer to native DNA conformation than genomic DNA (gDNA) isolated by the standard batch procedure. Using FTIR spectroscopy we analyzed the DNA methylation profile of isolated gDNA and compared it with the DNA-HALOs. This study demonstrated the potential of FTIR microspectroscopy to detect DNA methylation marks in analyzed DNA-HALO specimens more precisely in comparison with classical DNA extraction procedures that yield unstructured whole genomic DNA. In addition, we used different cell types to assess their global DNA methylation profile, as well as defined specific infrared peaks that can be used for screening DNA methylation.

Molecular Insights into the Mode of Action of Antibacterial Peptides Derived from Chicken Plasma Hydrolysates.

Due to the overuse and abuse of antibiotics, several antibiotic resistant bacteria have emerged. Antimicrobial peptides (AMPs) have gained attention as alternative antimicrobial agents because of their unique mode of action that impedes bacterial resistance. Two novel antibacterial peptides were isolated from Alcalase-hydrolyzed chicken plasma by size exclusion and reverse-phase chromatography. They were identified by LC-MS/MS to be VSDH and CCCPKAF, which showed effective antibacterial activity toward Bacillus cereus DMST 5040, with varied modes of action. The peptide CCCPKAF caused cell membrane disintegration, as evidenced by propidium iodide (PI) uptake. In contrast, the peptide VSDH targeted intracellular molecules, including proteins and nucleic acids, as revealed by Synchrotron-based Fourier Transform Infrared (SR-FTIR). The secondary structure of intracellular proteins increased to a β-sheet structure concomitant with a decrease in the α-helix structure when exposed to 0.5 mM VSDH. Molecular docking analysis revealed that VSDH showed high binding affinity for the active sites of the various enzymes involved in DNA synthesis. In addition, it showed good affinity for a chaperone protein (Dnak), resulting in the misfolding of intracellular proteins. Nuclear magnetic resonance (NMR) and molecular dynamics simulations also indicated that VSDH chelated well with Mg2+, which could partly contribute to its antibacterial activity.

Illuminating Host-Parasite Interaction at the Cellular and Subcellular Levels with Infrared Microspectroscopy.

Toxoplasma gondii (T. gondii) is an opportunistic protozoan that can cause brain infection and other serious health consequences in immuno-compromised individuals. This parasite has a remarkable ability to cross biological barriers and exploit the host cell microenvironment to support its own survival and growth. Recent advances in label-free spectroscopic imaging techniques have made it possible to study biological systems at a high spatial resolution. In this study, we used conventional Fourier-transform infrared (FTIR) microspectroscopy and synchrotron-based FTIR microspectroscopy to analyze the chemical changes that are associated with infection of human brain microvascular endothelial cells (hBMECs) by T. gondii (RH) tachyzoites. Both FTIR microspectroscopic methods showed utility in revealing the chemical alterations in the infected hBMECs. Using a ZnS hemisphere device, to increase the numerical aperture, and the synchrotron source to increase the brightness, we obtained spatially resolved spectra from within a single cell. The spectra extracted from the nucleus and cytosol containing the tachyzoites were clearly distinguished. RNA sequencing analysis of T. gondii-infected and uninfected hBMECs revealed significant changes in the expression of host cell genes and pathways in response to T. gondii infection. These FTIR spectroscopic and transcriptomic findings provide significant insight into the molecular changes that occur in hBMECs during T. gondii infection.

Live-Cell Synchrotron-Based FTIR Evaluation of Metabolic Compounds in Brain Glioblastoma Cell Lines after Riluzole Treatment.

Glioblastoma multiforme (GBM) is the most aggressive brain tumor, characterized by short median survival and an almost 100% tumor-related mortality. The standard of care treatment for newly diagnosed GBM includes surgical resection followed by concomitant radiochemotherapy. The prevention of disease progression fails due to the poor therapeutic effect caused by the great molecular heterogeneity of this tumor. Previously, we exploited synchrotron radiation-based soft X-ray tomography and hard X-ray fluorescence for elemental microimaging of the shock-frozen GBM cells. The present study focuses instead on the biochemical profiling of live GBM cells and provides new insight into tumor heterogenicity. We studied bio-macromolecular changes by exploring the live-cell synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy in a set of three GBM cell lines, including the patient-derived glioblastoma cell line, before and after riluzole treatment, a medicament with potential anticancer properties. SR-FTIR microspectroscopy shows that GBM live cells of different origins recruit different organic compounds. The riluzole treatment of all GBM cell lines mainly affected carbohydrate metabolism and the DNA structure. Lipid structures and protein secondary conformation are affected as well by the riluzole treatment: cellular proteins assumed cross β-sheet conformation while parallel β-sheet conformation was less represented for all GBM cells. Moreover, we hope that a new live-cell approach for GBM simultaneous treatment and examination can be devised to target cancer cells more specifically, i.e., future therapies can develop more specific treatments according to the specific bio-macromolecular signature of each tumor type.

Interrogation of IDH1 Status in Gliomas by Fourier Transform Infrared Spectroscopy.

Simple SummaryGliomas represent the vast majority of primary brain tumours and are of significant medical importance due to the poor clinical course of affected patients. The isocitrate dehydrogenase 1 (IDH1) mutation is associated with improved prognosis, compared to patients with IDH1-wildtype lesions of the same stage. In this proof-of-concept study, Fourier transform infrared spectroscopy was used to determine the IDH1 molecular status in fixed glioma sections. Classification algorithms successfully distinguished the two IDH1 classes with high accuracies (>80%). Knowledge of the IDH1 status would be beneficial, as maximum resection may be preferred in patients with IDH1-mutant gliomas, whilst a more limited resection can be best for IDH1-wildtype gliomas. Furthermore, we examined blood serum in an attempt to identify the biomolecular alterations caused by the IDH1 mutation. Non-invasive approaches that can detect the molecular status may guide some patients to an alternative treatment prior to surgery.Mutations in the isocitrate dehydrogenase 1 (IDH1) gene are found in a high proportion of diffuse gliomas. The presence of the IDH1 mutation is a valuable diagnostic, prognostic and predictive biomarker for the management of patients with glial tumours. Techniques involving vibrational spectroscopy, e.g., Fourier transform infrared (FTIR) spectroscopy, have previously demonstrated analytical capabilities for cancer detection, and have the potential to contribute to diagnostics. The implementation of FTIR microspectroscopy during surgical biopsy could present a fast, label-free method for molecular genetic classification. For example, the rapid determination of IDH1 status in a patient with a glioma diagnosis could inform intra-operative decision-making between alternative surgical strategies. In this study, we utilized synchrotron-based FTIR microanalysis to probe tissue microarray sections from 79 glioma patients, and distinguished the positive class (IDH1-mutated) from the IDH1-wildtype glioma, with a sensitivity and specificity of 82.4% and 83.4%, respectively. We also examined the ability of attenuated total reflection (ATR)-FTIR spectroscopy in detecting the biomolecular events and global epigenetic and metabolic changes associated with mutations in the IDH1 enzyme, in blood serum samples collected from an additional 72 brain tumour patients. Centrifugal filtration enhanced the diagnostic ability of the classification models, with balanced accuracies up to ~69%. Identification of the molecular status from blood serum prior to biopsy could further direct some patients to alternative treatment strategies.

FTIR micro-spectroscopy using synchrotron-based and thermal source-based radiation for probing live bacteria.

Fourier transform infrared (FTIR) spectroscopy has proven to be a non-invasive tool to analyse cells without the hurdle of employing exogenous dyes or probes. Nevertheless, the study of single live bacteria in their aqueous environment has long remained a big challenge, due to the strong infrared absorption of water and the small size of bacteria compared to the micron-range infrared wavelengths of the probing photons. To record infrared spectra of bacteria in an aqueous environment, at different spatial resolutions, two setups were developed. A custom-built attenuated total reflection inverted microscope was coupled to a synchrotron-based FTIR spectrometer, using a germanium hemisphere. With such a setup, a projected spot size of 1 × 1μm2 was achieved, which allowed spectral acquisition at the single-cell level in the 1800-1300cm-1 region. The second setup used a demountable liquid micro-chamber with a thermal source-powered FTIR microscope, in transmission geometry, for probing clusters of a few thousands of live cells in the mid-IR region (4000-975cm-1). Both setups were applied for studying two strains of a model lactic acid bacterium exhibiting different cryo-resistances. The two approaches allowed the discrimination of both strains and revealed population heterogeneity among bacteria at different spatial resolutions. The multivariate analysis of spectra indicated that the cryo-sensitive cells presented the highest cell heterogeneity and the highest content of proteins with the α-helix structure. Furthermore, the results from clusters of bacterial cells evidenced phosphate and peptidoglycan vibrational bands associated with the cell envelope, as potential markers of resistance to environmental conditions. Graphical Abstract.

Synchrotron-Based Infrared Microscopy Studies of the Radiosensitization Effects of Nanoparticles used in Radiotherapy

Radiotherapy (RT) is the most important non-surgical modality for cancer and the recent technological advances brought a substantial gain in the balance between the probability of tumor control and the risk of normal tissue complications. However, the clinical management of some radioresistant tumors (such as brain gliomas) continues being a challenge since tumor doses are constrained by the surrounding healthy tissue tolerances. Within this context, new modalities such as radiosensitization in the presence of high atomic number nanoparticles (NP) are extensively evaluated, with the main goal of enhancing the differential effect between tumors and healthy tissues. In the present work, Synchrotron based Fourier Transform Infrared Microspectroscopy (SR-FTIRM), a vibrational spectroscopic technique for the biochemical cell analysis on a microscopic scale, provides relevant information on the treatment-induced modifications of the main biomolecules (nucleic acids, proteins and lipids). A series of treatments, including various NP sized, typed and chemical natured (3 nm gadolinium (GdNP), 1.9 nm gold (AuNP) nanoparticles), cell line used (F98 murine and U87-MG human glioma cells) and radiotherapy configuration (megavoltage X-ray photon energy (MV) normaly used in clinics, with respect to kilovoltage photons (kV)), were assessed for their induced cell macromolecular damages (Martinez-Rovira et al. (2019) Analyst 144, 5511 and DOI: 10.1039/c9an01109a). Additionally, alongside X-ray photon RT, the possible cell damages caused by several charged particle beams (proton, helium, carbon and oxygen) were also considered. Briefly, the biochemical information provided by the highly brilliant infrared light source produced at ALBA Synchrotron leads to a clear advantage in spectral quality at a cellular level and allow better characterization of NP induced damage in cells.

Supercontinuum-based Fourier transform infrared spectromicroscopy

Fourier-transform infrared (FTIR) spectromicroscopy combines the spatial resolution of optical microscopy with the spectral selectivity of vibrational spectroscopy. Synchrotron sources can provide diffraction-limited beams in the infrared, and therefore synchrotron-based FTIR spectromicroscopy is nowadays an indispensable tool for biology and materials science studies where high spatial resolution is required. However, the increasing need for accurate and highly spatially resolved characterization is calling for alternative laboratory-based sources to complement synchrotron radiation. To date, the low brightness of thermal emitters or high temporal coherence and narrow bandwidth or tunability of laser sources have hindered the progress of bench-top FTIR spectromicroscopy. Here, we demonstrate that fiber-based supercontinuum sources in the mid-infrared enable fast spectral mapping of localized material properties with close to diffraction-limited resolution (3 μm×3 μm) and pave the way to table-top, on-demand, fast, and highly spatially resolved studies. We illustrate these capabilities by imaging thin sections of human liver samples and compare the results and performance with those obtained using a synchrotron source.

Fourier-transform spectra of metal salts of phytic acid in the mid- to far-infrared spectral range

Phytic acid (myo-inositol 1,2,3,4,5,6-hexakisphosphate; IP6) is the storage substance for phosphorus and many metals in plant seeds. Based on Synchrotron-based Fourier-transform infrared (FT-IR) spectra in the mid-infrared range from 1300 to 700cm−1, nine synthesized metal-IP6 salts, with monovalent to trivalent coordination, were classified into four groups: trivalent metal-IP6 salts, second-group divalent metal-IP6 salts, d-block and p-block divalent metal-IP6 salts, and monovalent metal-IP6 salts. Synchrotron FT-IR analysis in the far-infrared range, from 650 to 100cm−1, contained clear, broad bands specific to each metal-IP6 salt, including monovalent and divalent metal-IP6 salts. These broad bands are likely derived from vibrations of bonds between the metal and the oxygen of IP6. These unique far-infrared spectra may provide useful information for identifying metal-IP6 salts in biochemical fine-image analyses of seed tissues using synchrotron-based FT-IR microspectroscopy.

Molecular toxicity of triclosan and carbamazepine to green algae Chlorococcum sp.: A single cell view using synchrotron-based Fourier transform infrared spectromicroscopy

Although pharmaceuticals and personal care products have been used and introduced into the environment in large quantities, little information on potential ecological risks is currently available considering their effects on living organisms. We verified the feasibility of using synchrotron-based Fourier Transform Infrared (SR-FTIR) spectromicroscopy to explore in vivo toxic effects on single living Chlorococcum sp. cells. The study provided important information to achieve a better understanding of the toxic mechanism of triclosan and carbamazepine on living algae Chlorococcum sp.. Triclosan and carbamazepine had distinctive toxic effects on unicellular living algae. Most strikingly, triclosan had more dramatic toxic effects on biochemical components than carbamazepine. Triclosan can affect algae primarily by inhibiting fatty acid synthesis and causing protein aggregation. The toxicity response was irreversible at higher concentration (100.000 μM), but attenuated at lower concentration (0.391 μM) as time extended. Carbamazepine can produce hydrophobic interactions to affect the phospholipid bilayer and work on specific proteins to disfunction the cell membrane. Carbamazepine-exposed cells developed a resistance while extending exposure time. This is the first demonstration from an ecological standpoint that SR-FTIR can provide an innovative approach to reveal the toxicity of emerging pollutants in aquatic environments.

Synchrotron-based highest resolution FTIR spectroscopy of chlorobenzene

We report the Fourier Transform Infrared (FTIR) spectrum of chlorobenzene (C6H5Cl) measured using synchrotron radiation and the ETH-SLS 2009 prototype spectrometer at the Swiss Light Source (SLS). The maximum optical path difference of these measurements was 11.8m leading to a resolution of better than 0.0008cm−1. The spectra were taken at room temperature in the range 600–900cm−1. It was possible to analyze the in-plane mode ν12 of A1 symmetry (ν̃0=706.6686cm−1) and the out-of-plane mode ν10b of B1 symmetry (ν̃0=741.2240cm−1) of C6H535Cl. In addition, the ground state constant ΔK of C6H535Cl has been readjusted using combination differences (CD).

Synchrotron-based multiple-beam FTIR chemical imaging of a multi-layered polymer in transmission and reflection: towards cultural heritage applications

IRENI (infrared environmental imaging) is a recently commissioned Fourier transform infrared (FTIR) chemical imaging beamline at the Synchrotron Radiation Center in Madison, WI, USA. This novel beamline extracts 320 mrad of radiation, horizontally, from one bending magnet. The optical transport separates and recombines the beam into 12 parallel collimated beams to illuminate a commercial FTIR microspectrometer (Bruker Hyperion 3000) equipped with a focal plane array detector where single pixels in the detector image a projected sample area of either 0.54×0.54 μm2 or 2×2 μm2, depending in the measurement geometry. The 12 beams are partially overlapped and defocused, similar to wide-field microscopy, homogeneously illuminating a relatively large sample area compared to single-beam arrangements. Both transmission and reflection geometries are used to examine a model cross section from a layered polymer material. The compromises for sample preparation and measurement strategies are discussed, and the chemical composition and spatial definition of the layers are distinguished in chemical images generated from data sets. Deconvolution methods that may allow more detailed data analysis are also discussed.

Synchrotron radiation infrared microscopic study of non-bridging oxygen modes associated with laser-induced breakdown of fused silica

Nanosecond pulse laser-driven optical breakdown at SiO2 surfaces as probed by synchrotron-based Fourier transform infrared (SRFTIR) and photoluminescence (PL) microscopies is presented. SRFTIR mapping of laser damage identified localized non-bridging Si-O vibrational modes at ∼950 cm−1 which became stiffer as 355 nm laser pulse lengths were increased from 5 to 20 ns. The bridging Si-O-Si transverse optic mode frequency varied significantly across damaged regions indicating a wide range of average bond angles, softening slightly with increasing pulse length. 355 nm-excited PL images of laser modified regions could be directly correlated with the structural modifications identified through SRFTIR.

Multi-beam synchrotron infrared chemical imaging with high spatial resolution: Beamline realization and first reports on image restoration

Table-top Fourier transform infrared (FT-IR) imaging using focal plane array (FPA) multi-element detectors is an increasingly popular chemical microscopy technique because it can provide microspectroscopic images of large sample areas in short times at moderate spatial resolution. The novel IR beamline IRENI at the Synchrotron Radiation Center (Wisconsin, USA), the first dedicated multi-beam synchrotron-based FT-IR imaging system, offers, within minutes, high quality chemical images at the highest available spatial resolution (diffraction-limited at all mid-IR wavelengths) with a pixel size of 0.54×0.54 μm2 for transmission measurements. Due to this very high spatial sampling, mathematical image enhancement algorithms such as deconvolution and total variation (TV) reconstruction can be implemented to improve image contrast and thus spatial resolution. This is demonstrated for US Air force (USAF) targets, micron-sized aluminum beads, and a single living algal cell.

Application of Synchrotron Infrared Radiation in the Study of Organic Coatings in Cross-Sections

The characterization of organic materials in samples from historical objects is of special interest in conservation science and art history. In this study, synchrotron-based Fourier transform infrared (SR-FTIR) spectroscopy in reflection mode was used for the analysis of organic materials in multilayered samples mounted in cross-sections. In order to demonstrate the high potential of SR-FTIR in this field, samples of original furniture coatings were chosen as a relevant example. Standard samples were studied as well as cross-sections of samples from historical pieces of furniture from the eighteenth and nineteenth centuries. Layers within the cross-section can be analysed individually using this method with a spatial resolution in the lower micrometre range. The high brightness of the synchrotron source allows for the acquisition of high quality spectra that are useful for the distinction of several classes of organic materials. However, the identification of a specific substance within these classes by FTIR spectroscopy is often difficult or impossible.

The influence of phosphorus availability on carbon allocation and P quota in Scenedesmus subspicatus: A synchrotron-based FTIR analysis

D.C. Sigee, F. Bahrami, B. Estrada, R.E. Webster and A.P. Dean. 2007. The influence of phosphorus availability on carbon allocation and P quota in Scenedesmus subspicatus: A synchrotron-based FTIR analysis. Phycologia 46: 583–592. DOI: 10.2216/07-14.1Synchrotron-based Fourier transform infrared (FTIR) microspectroscopy was used to characterise the molecular composition of the freshwater alga Scenedesmus subspicatus, cultured at three different initial concentrations of phosphorus (PO4-P): 0.05 mg l−1, 0.5 mg l−1 and 5 mg l−1. These led, respectively, to limited algal growth due to phosphorus deficiency (low-P culture), maximum algal growth with no luxury consumption (intermediate-P) and maximum algal growth with luxury phosphorus consumption (high-P culture). In all cultures, FTIR spectra had nine major absorbance bands (wavenumber range 1760–900 cm−1), including bands at 1736 cm−1 (lipid), 1652 cm−1 (amide I) and the region from 1180 to 950 cm−1 (carbohydrate). Internal phosphorus concentrations (Qp), determined by energy dispersive X-ray microanalysis, differed markedly between low-P (typically < 0.1% dry wt), intermediate-P (> 0.1%) and high-P (> 0.3%) cultures. During logarithmic growth phase, a rapid change in carbon allocation was observed in the low-P cultures, with increases in both the lipid:protein (0.1–0.34) and carbohydrate:protein (0.4–1.0) ratio. Mean cell volume increased by 60%, and the mean chlorophyll a content remained consistently low (typically < 0.2 pg cell−1). The change in carbon allocation was triggered primarily by low Qp values rather than low external (culture medium) concentrations. Intermediate-P and high-P cultures showed higher chlorophyll a content (> 0.2 pg cell−1) and changes in carbon allocation only after entry into stationary phase. No increase in cell volume occurred, suggesting that a switch in carbon allocation during stationary phase (intermediate- and high-P cultures) rather than log phase (low-P culture) does not result in an increase in cell size. Entry into stationary growth phase occurred simultaneously in all three cultures and was not caused by internal (Qp) or external phosphorus depletion. Medium replacement in late stationary phase (day 35) cultures led to a rapid stimulation of growth, with a reversed carbon allocation (reduced lipid:protein and carbohydrate:protein ratios) and in low-P cultures a decrease in cell volume.