Multianalytical approach for surface- and tip-enhanced infrared spectroscopy study of a molecule-metal conjugate: deducing its adsorption geometry.

This study presents a multianalytical approach for surface-enhanced infrared absorption spectroscopy (SEIRA) and tip-enhanced infrared nanospectroscopy (TEIRA) studies of the α-methyl-dl-tryptophan adsorption geometry on a gold nanoparticle surface. Comparison of SEIRA spectra obtained in the transmission, attenuated total reflection and reflection modes verified the reproducibility of the adsorption. The application of the AutoSeagull (Harrick Scientific) accessory enabled us to track the dependence of the incident angle on the relative band intensity in the same area of the sample. Furthermore, the effect of two polarization modulations (p and s) in TEIRA was examined to deduce the adsorption geometry and to better understand the molecule/metal interaction. The nanogap between a gold-coated atomic force microscopy (AFM) tip and the gold surface induced electromagnetic enhancement in the optical field intensity. This is associated with the additional near-field electromagnetic field trapping effect. The local field intensity reinforcement significantly increased the infrared absorption cross-section of the compound under the tip with simultaneous improvement in spatial resolution. The originality of this study lies in the combination of various measurement modes and incident angles in SEIRA and two orthogonal polarizations in TEIRA to provide comprehensive characterization of the adsorption phenomenon. The results give important insights into tracking subtle changes in molecule geometry upon adsorption.

Vibrational microspectroscopy analysis of human lenses.

In this study we present vibrational analysis of healthy (non-affected by cataract) and cataractous human lenses by means of Raman and FTIR spectroscopy methods. The performed analysis provides complex information about the secondary structure of the proteins and conformational changes of the amino acid residues due to the formation of opacification of human lens. Briefly, the changes in the conformation of the Tyr and Trp residues and the protein secondary structure between the healthy and cataractous samples, were recognized. Moreover, the observed spectral pattern suggests that the process of cataract development does not occur uniformly over the entire volume of the lens.

Differentiation of protein secondary structure in clear and opaque human lenses: AFM - IR studies.

Here, we present the first approach to human lenses investigations with and without cataract development changes in nanoscale resolution using AFM - IR spectroscopy. We proved that the application of this technique allowed us to better understand of structural changes connected with advancing disease process in studied lenses. The obtained results show the impact of the disease development on the secondary structure of proteins in these human tissues. The domination of the ß-turn protein secondary structure is observed in the clear (non-affected by cataract) lens. While, in the case of the opaque (cataractous) samples the different degree of the degradation due to development of cataract, was recognized. Briefly, this process is associated with the protein secondary changes from ß-turn/ß-sheet parallel for less altered part of the lens to stable anti-parallel ß-sheet for the more degraded part. Interestingly, the AFM - IR technique provided estimation of the protein secondary structure without the need for using deconvolution procedure.

Is it possible to find presence of lactose in pharmaceuticals? - Preliminary studies by ATR-FTIR spectroscopy and chemometrics.

Lactose and saccharose have the same molecular formula; however, the arrangement of their atoms is different. A major difference between lactose and saccharose with regard to digestion and processing is that it is not uncommon for individuals to be lactose intolerant (around two thirds of the population has a limited ability to digest lactose after infancy), but it is rather unlikely to be saccharose intolerant. The pharmaceutical industry uses lactose and saccharose as inactive ingredients of drugs to help form tablets because of their excellent compressibility properties. Some patients with severe lactose intolerance may experience symptoms of many allergic reactions after taking medicine that contains this substance. People who are specifically "allergic" to lactose (not just lactose intolerant) should not use tablets containing this ingredient. Fourier Transform Infrared (FTIR) spectroscopy has a unique chemical fingerprinting capability and plays a significant important role in the identification and characterization of analyzed samples and hence has been widely used in pharmaceutical science. However, a typical FTIR spectrum collected from tablets contains a myriad of valuable information hidden in a family of tiny peaks. Powerful multivariate spectral data processing can transform FTIR spectroscopy into an ideal tool for high volume, rapid screening and characterization of even minor tablet components. In this paper a method for distinction between FTIR spectra collected for tablets with or without lactose is presented. The results seem to indicate that the success of identifying one component in FTIR spectra collected for pharmaceutical composition (that is tablet) is largely dependent on the choice of the chemometric technique applied.

SR-FTIR Coupled with Principal Component Analysis Shows Evidence for the Cellular Bystander Effect.

Synchrotron radiation-Fourier transform infrared (SR-FTIR) microscopy coupled with multivariate data analysis was used as an independent modality to monitor the cellular bystander effect. Single, living prostate cancer PC-3 cells were irradiated with various numbers of protons, ranging from 50-2,000, with an energy of either 1 or 2 MeV using a proton microprobe. SR-FTIR spectra of cells, fixed after exposure to protons and nonirradiated neighboring cells (bystander cells), were recorded. Spectral differences were observed in both the directly targeted and bystander cells and included changes in the DNA backbone and nucleic bases, along with changes in the protein secondary structure. Principal component analysis (PCA) was used to investigate the variance in the entire data set. The percentage of bystander cells relative to the applied number of protons with two different energies was calculated. Of all the applied quantities, the dose of 400 protons at 2 MeV was found to be the most effective for causing significant macromolecular perturbation in bystander PC-3 cells.

The pituitary gland under infrared light - in search of a representative spectrum for homogeneous regions.

The pituitary gland is a small but vital organ in the human body. It is located at the base of the brain and is often described as the master gland due to its multiple functions. The pituitary gland secretes and stores hormones, such as the thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), growth hormone (hGH), prolactin, gonadotropins, and luteinizing hormones, as well as the antidiuretic hormone (ADH). A proper diagnosis of pituitary disorders is of utmost importance as this organ participates in regulating a variety of body functions. Typical histopathological analysis provides much valuable information, but it gives no insight into the biochemical background of the changes that occur within the gland. One approach that could be used to evaluate the biochemistry of tissue sections obtained from pituitary disorders is Fourier Transform Infra-Red (FTIR) spectromicroscopy. In order to collect diagnostically valuable information large areas of tissue must be investigated. This work focuses on obtaining a unique and representative FTIR spectrum characteristic of one type of cell architecture within a sample. The idea presented is based on using hierarchical cluster analysis (HCA) for data evaluation to search for uniform patterns within samples from the perspective of FTIR spectra. The results obtained demonstrate that FTIR spectromicroscopy, combined with proper statistical evaluation, can be treated as a complementary method for histopathological analysis and ipso facto can increase the sensitivity and specificity for detecting various disorders not only for the pituitary gland, but also for other human tissues.

Neoplastic disorders of prostate glands in the light of synchrotron radiation and multivariate statistical analysis.

The prostate gland is the most common site of neoplastic disorders in men. The pathogenesis of inflammatory cells, prostatic intraepithelial neoplasia (PIN) lesions, and prostate cancer is still under investigation. Inflammatory cells by producing free radicals are considered as major and universal contributors to cancerogenesis. PIN is regarded as a precursor lesion to prostate cancer or a marker signaling the vulnerability of the epithelium to neoplastic transformation [1]. Differentiation markers that are frequently changed in early invasive carcinoma are also changed in PIN lesions. In this study, prostate tissue samples obtained during surgical operation and classified as various disease states (inflammation, PIN lesions, and cancer) were examined. The samples were measured by means of microbeam synchrotron-radiation-induced X-ray emission (micro-SRIXE). Special attention was paid to examine the relationship between the earlier-mentioned disorders and changes in relative concentrations of S, K, Ca, Fe, Cu, and Zn. Applying the image-processing program ImageJ enabled us to select the areas of interest from two-dimensional maps of various prostate samples according to the histopathologist's evaluation. Detailed analysis of micro-SRIXE spectra based on multivariate methods shows significant differences between elemental concentrations in inflammatory cells, PIN lesions, and cancerous tissues, which confirms that this method can be used to distinguish various pathological states in prostate tissues. Information obtained in this way may provide better understanding of the biochemistry of unhealthy prostate tissues, thus opening the way to find new medicines/treatments to prevent or slow down some harmful intracellular processes.

Correlation of concentrations of selected trace elements with Gleason grade of prostate tissues.

The causes of prostate cancer are still obscure but some evidence indicates that there is a close connection between several trace elements and processes which may lead to malignant cells. In our study the microbeam synchrotron radiation X-ray fluorescence emission (micro-SRIXE) technique was applied for quantitative analysis of selected elements. For the first time, we correlate the concentrations of Mn, Fe, Cu, and Zn with the clinical stage of the prostate cancer at the time of operation (described by Gleason grade). Serial sections of prostate tissues were collected from patients undergoing radical prostatectomy. One section, stained with hematoxylin and eosin, was prepared for histopathological analysis; a second, adjacent unstained section was used in micro-SRIXE experiments. All experiments were performed at beamline L at HASYLAB, DESY, Germany. Our results seem to be valuable in light of the determination of the changes in the concentrations of trace elements as a potential diagnostic marker and their etiological involvement in the different stages of prostate diseases.

FT-Raman, FT-IR spectroscopy and PIXE analysis applied to gallstones specimens.

Fourier transform Raman (FT-Raman) spectroscopy and Fourier transform infrared spectroscopy (FT-IR) were used as the main analytical techniques for the determination of human gallstone structural composition. These techniques provide rapid, qualitative and quantitative information about stone structure. The gallstones were obtained from. 40 patients during both surgical operations and laparoscopy. The results of FT-Raman and FT-IR analysis allowed to distinguish of four main groups of gallstones according their cholesterol and bilirubinate salt content. Our studies were extended to trace element analysis by means of proton induced X-ray emission (PIXE). On 14 elements detected, six elements Ca, Mn, Fe, Cu, Zn and Br were chosen for quantitative analysis. The concentration levels of these elements varied depending the chemical structure of the gallstones. The relationship between Ca and Cu appears to be of particular significance. In this paper a correlation between stone structure and trace element concentrations is presented.

X-ray fluorescence with synchrotron radiation.

The use of synchrotron radiation for X-ray fluorescence has several advantages over the use of other conventional X-ray sources. The principles of synchrotron radiation and methods for applying synchrotron radiation to the X-ray fluorescence measurements of trace elements are discussed. The Brookhaven National Laboratory X-ray microprobe, facilities dedicated to X-ray fluorescence, and related analytical techniques are discussed. Some examples of trace element analyses in biological materials with synchrotron radiation are presented.

Histochemical and quantitative determination of the mercury content in the spleen and bone marrow of mice.

The experiments were carried out on "Swiss" mice which received injections of mercuric chloride. The organs examined included the spleen and bone marrow. The detection of mercury in the cells of the above organs was performed according to the histochemical method developed by Timm[13]. In both cases Timm's Ioethod failed, proving to be invalid for determination of the lowest mercuric concentrations. By use of the hXE technique, it was found that the minimum concentration of mercury in the tissue detectable by cyto-chemical methods amounts to 0.65-1.0 ppm.