Synchrotron Radiation-based Fourier Transform Infrared Microspectroscopy Research Articles

Development of a machine learning model for systematics of Aspergillus section Nigri using synchrotron radiation-based fourier transform infrared spectroscopy

Aspergillus section Nigri (black aspergilli) fungi are economically important food spoilage agents. Some species in this section also produce harmful mycotoxins in food. However, it is remarkably difficult to identify this fungal group at the species level using morphological and chemical characteristics. The molecular approach for classification is preferable; however, it is time-consuming, making it inappropriate for rapid testing of large numbers of samples. To address this, we explored synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-FTIR) as a rapid method for obtaining data suitable for species classification. SR-FTIR data were obtained from the mycelia/conidia of 22 black aspergilli species. The Convolutional Neural Network (CNN) approach, a supervised deep learning algorithm, was used with SR-FTIR data to classify black aspergilli at the species level. A subset of the data was used to train the CNN model, and the model classification performance was evaluated using the validation data subsets. The model demonstrated a 95.97% accuracy in species classification on the testing (blind) data subset. The technique presented herein could be an alternative method for identifying problematic black aspergilli in the food industry.

Quantitative biochemical phenotypic heterogeneity of macrophages after myelin debris phagocytosis at a single cell level by synchrotron radiation fourier transform infrared microspectroscopy

During the immuno-inflammatory pathophysiological process of spinal cord injury, traumatic brain injury, and ischemic stroke, macrophages play an important role in phagocytizing and clearing degenerated myelin debris. After phagocytizing myelin debris, the biochemical phenotypes related to the biological function of macrophages show vast heterogeneity; however, it is not fully understood. Detecting biochemical changes after myelin debris phagocytosis by macrophages at a single-cell level is helpful to characterize phenotypic and functional heterogeneity. In this study, based on the cell model of myelin debris phagocytosis by macrophages in vitro, the biochemical changes in macrophages were investigated using Synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy. Infrared spectrum fluctuations, principal component analysis, and cell-to-cell Euclidean distance statistical analysis of specific spectrum regions revealed dynamic and significant changes in proteins and lipids within macrophages after myelin debris phagocytosis. Thus, SR-FTIR microspectroscopy is a powerful identification toolkit for exploring biochemical phenotype heterogeneity transformation that may be of great importance to providing an evaluation strategy for studying cell functions related to cellular substance distribution and metabolism.

Heating temperatures affect meat quality and vibrational spectroscopic properties of slow- and fast-growing chickens

This study determined the effect of water bath cooking (70°C and 90°C for 40 min) and the extreme heat treatment by an autoclave (121°C for 40 min) on the quality of breast meat of a fast-growing chicken, commercial broiler (CB), and slow-growing chickens, Korat chicken (KC), and Thai native chicken (NC) (Leung Hang Khao), by vibrational spectroscopic techniques, including synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy and Fourier transform Raman (FT-Raman) spectroscopy. Taste-enhancing compounds, including inosine-5'-monophosphate (IMP) and guanosine-5'-monophosphate (GMP), were better retained in cooked KC and NC meats than in cooked CB meat (P < 0.05). The high heat treatment at 121°C depleted the amount of insoluble collagen in all breeds (P < 0.05). Shear force values of slow-growing chicken meat were not affected by high heating temperatures (P > 0.05). In addition, the high heat treatment increased protein carbonyl (P < 0.05), while no effect on in vitro protein digestibility (P > 0.05). SR-FTIR microspectroscopy performed better in differentiating the meat quality of different chicken breeds, whereas FT-Raman spectroscopy clearly revealed differences in meat qualities induced by heating temperature. Based on principal component analysis (PCA), distinct characteristics of chicken meat cooked at 70°C were high water-holding capacity, lightness (L*), moisture content, and predominant α-helix structure, correlating with Raman spectra at 3,217 cm-1 (O-H stretching of water) and 1,651 cm-1 (amide I; α-helix). The high heating temperature at 90°C and 121°C exposed protein structure to a greater extent, as evidenced by an increase in β-sheets, which was well correlated with the Raman spectra at 2,968 and 2,893 cm-1 (C-H stretching), tryptophan (880 cm-1), tyrosine (858 cm-1), and 1,042, 1,020, and 990 cm-1 (C-C stretching; β-sheet). SR-FTIR and FT-Raman spectroscopy show potential for differentiation of chicken meat quality with respect to breeds and cooking temperatures. The marked differences in wavenumbers would be beneficial as markers for determining the quality of cooked meats from slow- and fast-growing chickens.

Characterization of Different Types of Epiretinal Proliferations by Synchrotron Radiation-Based Fourier Transform Infrared Micro-Spectroscopy

Pathological tissue on the surface of the retina that can be of different etiology and pathogenesis can cause changes in the retina that have a direct consequence on vision. Tissues of different etiology and pathogenesis have different morphological structures and also different macromolecule compositions usually characteristic of specific diseases. In this study, we evaluated and compared biochemical differences among samples of three different types of epiretinal proliferations: idiopathic epiretinal membrane (ERMi), membranes in proliferative vitreoretinopathy (PVRm), and proliferative diabetic retinopathy (PDRm). The membranes were analyzed by using synchrotron radiation-based Fourier transform infrared micro-spectroscopy (SR-FTIR). We used the SR-FTIR micro-spectroscopy setup, where measurements were set to achieve a high resolution that was capable of showing clear biochemical spectra in biological tissue. We were able to identify differences between PVRm, PDRm, and ERMi in protein and lipid structure; collagen content and collagen maturity; differences in proteoglycan presence; protein phosphorylation; and DNA expression. Collagen showed the strongest expression in PDRm, lower expression in ERMi, and very low expression in PVRm. We also demonstrated the presence of silicone oil (SO) or polydimethylsiloxane in the structure of PVRm after SO endotamponade. This finding suggests that SO, in addition to its many benefits as an important tool in vitreoretinal surgery, could be involved in PVRm formation.

Biomacromolecular Profile in Human Primary Retinal Pigment Epithelial Cells—A Study of Oxidative Stress and Autophagy by Synchrotron-Based FTIR Microspectroscopy

Synchrotron radiation-based Fourier Transform Infrared (SR-FTIR) microspectroscopy is a non-destructive and chemically sensitive technique for the rapid detection of changes in the different components of the cell's biomacromolecular profile. Reactive oxygen species and oxidative stress may cause damage to the DNA, RNA, and proteins in the retinal pigment epithelium (RPE), which can further lead to age-related macular degeneration (AMD) and visual loss in the elderly. In this study, human primary RPEs (hRPEs) were used to study AMD pathogenesis by using an established in vitro cellular model of the disease. Autophagy-a mechanism of intracellular degradation, which is altered during AMD, was studied in the hRPEs by using the autophagy inducer rapamycin and treated with the autophagy inhibitor bafilomycin A1. In addition, oxidative stress was induced by the hydrogen peroxide (H2O2) treatment of hRPEs. By using SR-FTIR microspectroscopy and multivariate analyses, the changes in the phosphate groups of nucleic acids, Amide I and II of the proteins, the carbonyl groups, and the lipid status in the hRPEs showed a significantly different pattern under oxidative stress/autophagy induction and inhibition. This biomolecular fingerprint can be evaluated in future drug discovery studies affecting autophagy and oxidative stress in AMD.

Synchrotron Radiation FTIR Microspectroscopy Study of Biomolecular Alterations in Vincristine-Treated WRL68 Cells at the Single-Cell Level.

The toxic effect of vincristine on hepatocytes has rarely been studied. Synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy is a novel technique for investigating drug-cell interaction systems. In this research, the biomolecular alterations in WRL68 cells induced by vincristine treatment were investigated by SR-FTIR microspectroscopy and were further analyzed by multivariate statistical analysis and semiquantitative methods, including principal component analysis (PCA), orthogonal partial least square-discriminant analysis (OPLS-DA), and the peak area ratios of several characteristic IR bands. In vincristine-treated WRL68 cells, alterations in lipid structures and the presence of more long-chain fatty acids were found. A decrease in protein α-helical content relative to β-sheet structures in vincristine-treated WRL68 cells was identified. The nucleic acid content was decreased relative to that of lipids and proteins in WRL68 cells treated with vincristine. These results provide important information about the toxic effect of vincristine on normal liver cells. This research also provides a new approach to reveal the biomolecular alterations in drug-treated hepatocytes by combining SR-FTIR with multivariate statistical analysis and semiquantitative methods.

Synchrotron FTIR investigations of kerogen from Proterozoic organic-walled eukaryotic microfossils.

Fourier transform infrared spectroscopy (FTIR) provides a rapid non-destructive molecular characterization of organic and inorganic material in geological samples. Combination of qualitative and semi-quantitative approaches are routinely used in FTIR study of kerogen and coals. A diversity of descriptors provides straightforward tools to characterize kerogen type, composition and structure. However, only a few of these descriptors are applied in the chemical investigation of Precambrian organic-walled microfossils. Synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-FTIR) permits high spatial resolution investigations of organic matter in a large range of applications in biology, geochemistry and cosmochemistry, but remains rarely applied in Precambrian microfossils studies. Here we show that SR-FTIR spectroscopy combined with an integrative approach of kerogen description is particularly relevant for the study of minute organic-walled microfossils of unknown biological origin. The analyses of five morphospecies from three different Proterozoic formations in northwestern Canada highlight kerogen signatures rich in aromatic, aliphatic and oxygenated moieties. This is evidenced by the combined use of spectrum qualitative descriptions (band assignments and positions) and the calculations of semi-quantitative parameters using intensities and integrated areas of absorption bands (CH2/CH3, R3/2, Al/CC, CO/CC, A factor, C factor). Altogether, this study demonstrates the interest of an integrative approach when investigating the chemistry of organic-walled microfossils with FTIR spectroscopy.

Synchrotron radiation-based Fourier transform infrared microspectroscopy investigation of WRL68 cells treated with doxorubicin

Doxorubicin is an effective chemotherapeutic agent applied in a wide variety of cancers. Despite its potent anticancer activity towards cancer cells, doxorubicin is also toxic to noncancerous cells. Therefore, doxorubicin can cause serious side effects in various organs, especially when dose escalation is required for patients with advanced disease. The liver is the major detoxification organ that metabolizes drugs, and hepatotoxicity is one of the most common adverse effects of doxorubicin administration. However, the exact mechanisms of doxorubicin-induced hepatotoxicity have not been clearly identified, and how doxorubicin treatment affects the biomolecular contents of normal human hepatocytes has rarely been studied. Synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy is a state-of-the-art analytical technique for characterizing the biomolecules present in cells. In this research, the biomolecular alterations of doxorubicin-treated normal human hepatocytes compared to untreated control cells were investigated at the single-cell level by combining SR-FTIR microspectroscopy with the Cell Counting Kit-8 (CCK-8) assay and flow cytometry. WRL68 human normal embryonic liver cells, which have been shown to be very promising for assessing the cytotoxicity of toxic compounds and investigating hepato-toxicology, were used in this research. Principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were used to further analyse the biomolecular contents of WRL68 cells. The order of lipid acyl chains and protein α-helix structures in doxorubicin-treated WRL68 cells was found to be distinctly changed, while the nucleic acids were altered relatively less. No alteration in the carbohydrate content was distinguishable after doxorubicin treatment. These results provide more comprehensive information about the biomolecular changes in hepatocytes induced by doxorubicin treatment and help to elucidate the mechanism of doxorubicin-induced hepatotoxicity. This research also proves that SR-FTIR microspectroscopy, combined with PCA and OPLS-DA, is a promising approach for investigating drug-cell interaction systems.

Analysis and comparison of protein secondary structures in the rachis of avian flight feathers.

Avians have evolved many different modes of flying as well as various types of feathers for adapting to varied environments. However, the protein content and ratio of protein secondary structures (PSSs) in mature flight feathers are less understood. Further research is needed to understand the proportions of PSSs in feather shafts adapted to various flight modes in different avian species. Flight feathers were analyzed in chicken, mallard, sacred ibis, crested goshawk, collared scops owl, budgie, and zebra finch to investigate the PSSs that have evolved in the feather cortex and medulla by using nondestructive attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). In addition, synchrotron radiation-based, Fourier transform infrared microspectroscopy (SR-FTIRM) was utilized to measure and analyze cross-sections of the feather shafts of seven bird species at a high lateral resolution to resolve the composition of proteins distributed within the sampled area of interest. In this study, significant amounts of α-keratin and collagen components were observed in flight feather shafts, suggesting that these proteins play significant roles in the mechanical strength of flight feathers. This investigation increases our understanding of adaptations to flight by elucidating the structural and mechanistic basis of the feather composition.

Infrared spectroscopic imaging study of BV-2 microglia altering tumor cell biological activity and cellular fraction

Tumor brain metastasis is a severe threat to patients’ neurological function, in which microglia may be involved in the process of tumor cell metastasis among nerve cells. Our study focused on the interaction between microglia and breast and lung cancer cells. Changes in the proliferation and migration ability of cocultured tumor cells were examined; synchrotron radiation-based fourier transform infrared microspectroscopy (SR-FTIR) was used to detect changes in the structures and contents of biomolecules within the tumor cells. The experimental results showed that the proliferation and migration ability of tumor cells increased after coculture, and the structures and contents of biological macromolecules in tumor cells changed. The absorption peak positions of the amide Ⅱ and amide Ⅰ bands observed for the four kinds of tumor cells changed, and the absorption intensities were significantly enhanced, indicating changes in the secondary structures and contents of proteins in tumor cells, which may be the root cause of the change in tumor cell characteristics. Therefore, the metabolites of microglia may be involved in the progression of tumor cells in the nervous system. In this study, we focused on the interaction between microglia and tumor cells by using SR-FTIR and provided a new understanding of the mechanism of brain metastasis.

Graphene Oxide-Induced Protein Conformational Change in Nasopharyngeal Carcinoma Cells: A Joint Research on Cytotoxicity and Photon Therapy.

The objectives of this work aim to investigate the interaction and cytotoxicity between nanometric graphene oxide (GO) and nasopharyngeal carcinoma cells (NPC-BM1), and possible application in photon therapy. GO nanosheets were obtained in the size range of 100–200 nm, with a negative surface charge. This nanometric GO exhibited a limited (<10%) cytotoxicity effect and no significant dimensional change on NPC-BM1 cells in the tested GO concentration range (0.1–10 µg·mL−1). However, the secondary protein structure was modified in the GO-treated NPC-BM1 cells, as determined through synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-FTIRM) mapping. To further study the cellular response of GO-treated NPC-BM1 cancer cells at low GO concentration (0.1 µg·mL−1), photon radiation was applied with increasing doses, ranging from 2 to 8 Gy. The low radiation energy (<5 Gy) did not cause significant cell mortality (5–7%). Increasing the radiation energy to 6–8 Gy accelerated cell apoptosis rate, especially in the GO-treated NPC-BM1 cells (27%). This necrosis may be due to GO-induced conformational changes in protein and DNA/RNA, resulting in cell vulnerability under photon radiation. The findings of the present work demonstrate the potential biological applicability of nanometric GO in different areas, such as targeted drug delivery, cellular imaging, and radiotherapy, etc.

Synchrotron-based FTIR microspectroscopy of protein aggregation and lipids peroxidation changes in human cataractous lens epithelial cells

Cataract is the leading cause of blindness worldwide but the mechanisms involved in the process of cataractogenesis are not yet fully understood. Two most prevalent types of age-related cataracts are nuclear (N) and cortical (C) cataracts. A common environmental factor in most age-related cataracts is believed to be oxidative stress. The lens epithelium, the first physical and biological barrier in the lens, is build from lens epithelial cells (LECs). LECs are important for the maintenance of lens transparency as they control energy production, antioxidative mechanisms and biochemical transport for the whole lens. The purpose of this study is to characterize compounds in LECs originated from N and C cataracts, by using the synchrotron radiation-based Fourier Transform Infrared (SR-FTIR) microspectroscopy, in order to understand the functional importance of their different bio-macromolecules in cataractogenesis. We used the SR-FTIR microspectroscopy setup installed on the beamline MIRAS at the Spanish synchrotron light source ALBA, where measurements were set to achieve single cell resolution, with high spectral stability and high photon flux. The results showed that protein aggregation in form of fibrils was notably pronounced in LECs of N cataracts, while oxidative stress and the lipids peroxidation were more pronounced in LECs of C cataracts.

A highly efficient pathway to recover gold from acid aqueous solution by using an amidoxime-functionalized UHMWPE fiber

A new amidoxime-functionalized ultrahigh molecular weight polyethylene fibrous adsorbent (UHMWPE-g-PAO) was used for the recovery of Au(III) from acid aqueous solution. The maximum experimental absorption capacity of UHMWPE-g-PAO fiber was found to be approximately 220.0 mg·g−1. Au adsorption on UHMWPE-g-PAO was characterized by synchrotron radiation-based microcomputed tomography (SR-μ-CT), transmission electron microscopy (TEM), X-ray absorption near-edge structure spectroscopy (XANES) and synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-FTIR). The SR-μ-CT and TEM results showed the distribution features of gold particles on the fiber. The mechanism of Au(III) recovery from aqueous solutions by UHMWPE-g-PAO was based on the adsorbed Au(III) ions, which were reduced to metallic zero-valent gold (Au(0)) by amino groups (–NH2) in the amidoxime (AO) groups during the adsorption process, as confirmed by high-resolution TEM (HRTEM) and XANES analyses. X-ray diffraction (XRD) results indicated that the incineration ashes contained metallic zero-valent gold. In conclusion, this amidoxime-functionalized fibrous adsorbent is a promising material for recovering gold from aqueous solution.

Detect molecular spectral features of newly developed Vicia faba varieties and protein metabolic characteristics in ruminant system using advanced synchrotron radiation based infrared microspectroscopy: A preliminary study.

Recently, advanced synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-IMS) has been developed as a rapid, direct, non-destructive and bioanalytical technique. To date, there has been very little application of this technique to study the molecular structure make-up in pulse seeds. Thus, the objectives of this study were to detect the interactive association between protein molecular structure and nutrient availability of newly developed Vicia faba varieties. Two different varieties of faba beans (CDC Snowdrop = low-tannin variety; vs. FB9-4 = high-tannin variety) were selected for this study. The molecular spectra data were collected by using SR-IMS. The ratio of both amide I to II area and height were higher (P < 0.01), while the ratio of α-helix to β-sheet was lower (P < 0.05) in CDC Snowdrop compared to FB9-4. The crude protein (CP) content and the predicted truly digestible nutrients as well as the bioenergy values did not vary between two varieties. The CDC Snowdrop had exhibited a higher (P < 0.01) rapidly degradable CP fraction (75.99 vs. 71.45% on CP) and a lower (P < 0.01) moderately degradable CP fraction (19.43 vs. 22.85% on CP), resulting in a higher (P < 0.01) rumen degradable protein and a lower (P < 0.01) rumen undegradable protein content than that of FB9-4 variety. However, the total supply of digestible rumen undegraded feed protein was higher (P < 0.05) in FB9-4 than CDC Snowdrop. Strong positive correlations were found between the ratio of α-helix to β-sheet and CP contents (R = 0.86, P < 0.01) as well as the truly digestible CP contents (R = 0.83, P < 0.01); respectively. In conclusion, the results of this study reveal that the protein are metabolized differently between different type of faba bean varieties and the advanced SR-IMS molecular spectroscopy can be used to rapidly delineate protein molecular structure motifs along with their nutritive value in ruminant livestock system.

SR-FTIR as a tool for quantitative mapping of the content and distribution of extracellular matrix in decellularized book-shape bioscaffolds

BackgroundTo evaluate synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-FTIR) as a tool for quantitative mapping of the content and distribution of the extracellular matrix in decellularized fibrocartilage bioscaffolds, and to provide a new platform for quantitatively characterizing bioscaffolds for tissue engineering.MethodsFibrocartilage was harvested and cut into book-shape bioscaffolds (N = 54), which were then decellularized. The structures and distribution of collagen fibrous and intrinsic ultrastructure in decellularized fibrocartilage bioscaffolds were evaluated by histological staining and scanning electron microscopy (SEM), respectively. The content of collagen and proteoglycan in the cellularized or decellularized bioscaffolds were also measured by SR-FTIR and biochemical assay.ResultsBook-shape fibrocartilage decellularized bioscaffolds were successfully obtained. Histological examination revealed that the structure of extracellular matrix endured during decellularization. Histology and DNA quantification analysis confirmed substantial removal of cells during decellularization. SEM demonstrated that intrinsic ultrastructure of the fibrocartilage bioscaffold was also well preserved. SR-FTIR quantitative analysis confirmed that decellularization had a significant effect on the content and distribution of collagen and proteoglycan in fibrocartilage bioscaffolds, these results are confirmed with the biochemical assay results.ConclusionSR-FTIR imaging can capture the histological morphology of decellularized bioscaffolds. Moreover, it can be used for quantitative mapping of the content and distribution of collagen in the bioscaffolds.

Synchrotron- and focal plane array-based Fourier-transform infrared spectroscopy differentiates the basalis and functionalis epithelial endometrial regions and identifies putative stem cell regions of human endometrial glands

The cyclical process of regeneration of the endometrium suggests that it may contain a cell population that can provide daughter cells with high proliferative potential. These cell lineages are clinically significant as they may represent clonogenic cells that may also be involved in tumourigenesis as well as endometriotic lesion development. To determine whether the putative stem cell location within human uterine tissue can be derived using vibrational spectroscopy techniques, normal endometrial tissue was interrogated by two spectroscopic techniques. Paraffin-embedded uterine tissues containing endometrial glands were sectioned to 10-μm-thick parallel tissue sections and were floated onto BaF2 slides for synchrotron radiation-based Fourier-transform infrared (SR-FTIR) microspectroscopy and globar focal plane array-based FTIR spectroscopy. Different spectral characteristics were identified depending on the location of the glands examined. The resulting infrared spectra were subjected to multivariate analysis to determine associated biophysical differences along the length of longitudinal and crosscut gland sections. Comparison of the epithelial cellular layer of transverse gland sections revealed alterations indicating the presence of putative transient-amplifying-like cells in the basalis and mitotic cells in the functionalis. SR-FTIR microspectroscopy of the base of the endometrial glands identified the location where putative stem cells may reside at the same time pointing towards νsPO2− in DNA and RNA, nucleic acids and amide I and II vibrations as major discriminating factors. This study supports the view that vibration spectroscopy technologies are a powerful adjunct to our understanding of the stem cell biology of endometrial tissue.Graphical abstractᅟ

Tracking hidden organic carbon in rocks using chemometrics and hyperspectral imaging

Finding traces of life or organic components of prebiotic interest in the rock record is an appealing goal for numerous fields in Earth and space sciences. However, this is often hampered by the scarceness and highly heterogeneous distribution of organic compounds within rocks. We assess here an innovative analytical strategy combining Synchrotron radiation-based Fourier-Transform Infrared microspectroscopy (S-FTIR) and multivariate analysis techniques to track and characterize organic compounds at the pore level in complex oceanic rocks. S-FTIR hyperspectral images are analysed individually or as multiple image combinations (multiset analysis) using Principal Component Analyses (PCA) and Multivariate Curve Resolution – Alternating Least Squares (MCR-ALS). This approach allows extracting simultaneously pure organic and mineral spectral signatures and determining their spatial distributions and relationships. MCR-ALS analysis provides resolved S-FTIR signatures of 8 pure mineral and organic components showing the close association at a micrometric scale of organic compounds and secondary clays formed during rock alteration and known to catalyse organic synthesis. These results highlights the potential of the serpentinizing oceanic lithosphere to generate and preserve organic compounds of abiotic origin, in favour of the hydrothermal theory for the origin of life.

Discrimination of foodborne pathogenic bacteria using synchrotron FTIR microspectroscopy

Traditional Fourier transform infrared (FTIR) spectroscopy has been recognized as a valuable method to characterize and classify kinds of microorganisms. In this study, combined with multivariate statistical analysis, synchrotron radiation-based FTIR (SR-FTIR) microspectroscopy was applied to identify and discriminate ten foodborne bacterial strains. Our results show that the whole spectra (3000–900 cm -1 ) and three subdivided spectral regions (3000–2800, 1800–1500 and 1200–900 cm -1 , representing lipids, proteins and polysaccharides, respectively) can be used to type bacteria. Either the whole spectra or the three subdivided spectra are good for discriminating the bacteria at levels of species and subspecies, but the whole spectra should be given preference at the genus level. The findings demonstrate that SR-FTIR microspectroscopy is a powerful tool to identify and classify foodborne pathogenic bacteria at the genus, species and subspecies level.

Hydration induced material transfer in membranes of osmotic pump tablets measured by synchrotron radiation based FTIR

Osmotic pump tablets are reliable oral controlled drug delivery systems based on their semipermeable membrane coating. This research used synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy and imaging to investigate the hydration induced material transfer in the membranes of osmotic pump tablets. SR-FTIR was applied to record and map the chemical information of a micro-region of the membranes, composed of cellulose acetate (CA, as the water insoluble matrix) and polyethylene glycol (PEG, as the soluble pore forming agent and plasticizing agent). The microstructure and chemical change of membranes hydrated for 0, 5, 10 and 30min were measured using SR-FTIR, combined with scanning electronic microscopy and atom force microscopy. The SR-FTIR microspectroscopy results indicated that there was a major change at the absorption range of 2700–3100cm−1 in the membranes after different periods of hydration time. The absorption bands at 2870–2880cm−1 and 2950–2960cm−1 were assigned to represent CA and PEG, respectively. The chemical group signal distribution illustrated by the ratio of PEG to CA demonstrated that the trigger of drug release in the preliminary stage was due to the rapid transfer of PEG into liquid medium with a sharp decrease of PEG in the membranes. The SR-FTIR mapping results have demonstrated the hydration induced material transfer in the membranes of osmotic pump tablets and enabled reassessment of the drug release mechanism of membrane controlled osmotic pump systems.

Combination of synchrotron radiation-based Fourier transforms infrared microspectroscopy and confocal laser scanning microscopy to understand spatial heterogeneity in aquatic multispecies biofilms

Understanding the spatial heterogeneity within environmental biofilms can provide an insight into compartmentalization of different functions in biofilm communities. We used a non-destructive and label-free method by combining Synchrotron Radiation-based Fourier Transform Infrared Microspectroscopy (SR-FTIR) with Confocal Laser Scanning Microscopy (CLSM) to distinguish the spatial chemical changes within multispecies biofilms grown from natural storm waters in flow cells. Among the different surfaces tested for biofilm growth and optimal imaging, mylar membranes were most suited and it enabled successful spatial infrared imaging of natural biofilms for obtaining reliable and interpretable FTIR spectra. Time series analysis of biofilm growth showed that influx of water during biofilm growth, results in significant changes in biofilm formation. Early biofilms showed active nutrient acquisition and desiccation tolerance mechanisms corresponding with accumulation of secreted proteins. Statistical approach used for the evaluation of chemical spectra allowed for clustering and classification of various regions of the biofilm. Microheterogeneity was observed in the polymeric components of the biofilm matrix, including cellulose, glycocalyx and dextran-like molecules. Fructan and glycan-rich regions were distinguishable and glycocalyx was abundant in the strongly adhering peripheral regions of biofilms. Inner core showed coexistence of oxygen dimers and ferrihydrite that will likely support growth of Fe (II)-oxidising bacteria. The combined SR-FTIR microspectroscopy and CSLM approach for complex natural biofilms described here will be useful both in understanding heterogeneity of matrix components and in correlating functions of juxtaposed microbial species in complex natural biofilms with physicochemical microenvironment to which they are exposed.