Giorgio Tosi

Microimaging FTIR of head and neck tumors. IV.

On continuing our studies on head and neck neoplasia, specimens from salivary gland tumors have been explored by using infrared microimaging spectroscopy to discern healthy from neoplastic tissues. Samples with Warthin tumor, epithelial displasia, marginal B‐cell lymphoma, low‐grade adenocarcinoma, and adenoid cystic carcinoma pathologies have been investigated by using conventional light sources. Changes were monitored at the molecular level, probing spectral markers such as Amide I and II, phosphate, nucleic acids, and carbohydrates vibrational modes. In all cases, supervised and unsupervised spectral analyses resulted in satisfactory agreement with histopathological findings. Microsc. Res. Tech., 2009.

FT-IR study of two [2-oxo-pyrrolidin-4-yl]carboxylate diastereomers in different solvent systems

Abstract The infrared study of the solvent effect on two diasteroisomeric (3R)- and (3S)-1-[(R)-1-phenylethyl]-2-oxo-pyrrolidin-4-yl-carboxylates ( A and B ) acting as homo- β -proline inhibitory neurotransmitter precursors, is reported. Apart from the slight red shift of the carbonyl bands of A , the interactions of the title compounds with the solvents are comparable. In hydroxylic solvents, the solutes are hosts in intermolecularly H-bonded alcohol clusters, the percentage of specific solute–solvent interaction being higher for compound A . This result confirms theoretical findings and X-ray diffraction studies.

Histological and microscopy FT-IR imaging study on the proliferative activity and angiogenesis in head and neck tumours.

Micro Fourier transform infrared spectroscopy enables one to study small samples because of the high quality spectra that can be obtained. Biochemical and morphological changes between control and pathological tissues of head and neck tumours have been monitored drawing three-dimensional chemical maps of the main vibrational modes in the regions of interest. Comparison between spectral and histological data shows a satisfactory degree of accordance. Among all, proliferating and regressive states of the tumours can be identified.

FTIR microspectroscopy of melanocytic skin lesions: a preliminary study

Fourier transform infrared (FTIR) microspectroscopy has been employed to investigate benign (ordinary dermal and Reed nevi), dysplastic and malignant (invasive melanoma) skin lesions through the analysis of spectral changes of melanocytes as well as in the evaluation of the presence of melanin. Hierarchical cluster analysis and principal component analysis led to a satisfactory separation of malignant from dysplastic and normal melanocytes. Also, on enlarging the clustering with spectra from Reed and dermal nevi, the multivariate analysis segregated well the spectral data into discrete clusters, allowing the obtaining of reliable average spectra for analysis at the molecular level of the main groups or components responsible for the biological and biochemical changes. The most significant spectral characteristics appear to be related to differences in secondary protein structures, in nucleic acid conformation, in intra- and intermolecular bonding. In all cases, supervised and unsupervised spectral analyses resulted in satisfactory agreement with histopathological findings.

Complexes of azobisindoles with π-organic acceptors

Complexes of azobisindoles with tetracyanoethylene and tetracyanoquinodimethane were studied by UV-Vis, FT-IR, Raman, NMR and X-ray spectroscopies. FT-IR and Raman spectra, as well as X-ray analysis, gave useful information on the participation of various sites to the association, through analysis of CN and N=N vibrational modes, while UV-Vis and NMR spectra were less helpful. The crystal structure of complexes 1-ethyl-2-phenyl-3-(1-ethyl-2-phenyl-3-azoindole)indole/TCNE,3a and 1,2-diphenyl-3-(1,2-diphenyl-3-azoindole)indole/TCNQ,5b are reported. In the two complexes, the distances between donor and acceptor planes range between 3.4 and 3.5 Å; in3a tetracyanoethylene faces the phenyl ring of the indole, while in5b the superposition of tetracyanoquinodimethane with the donor is negligible. Compound3a,P−1,a=9.504(2),b=9.513(3),c=8.941(2) Å, α=97.81(4), β=103.38(3), γ=84.14(2)°,Z=2,Dcalc=2.55 g cm−3; compound5b,P−1,a=12.648(3),b=12.205(2),c=7.263(3) Å, α=103.69(2), β=91.23(3), γ=110.61(2)°,Z=2,Dcalc=2.53 g cm−3.

Electrospun Nanostructured Fibers of Collagen-Biomimetic Apatite on Titanium Alloy

Titanium and its alloys are currently the mainly used materials to manufacture orthopaedic implants due to their excellent mechanical properties and corrosion resistance. Although these materials are bioinert, the improvement of biological properties (e.g., bone implant contact) can be obtained by the application of a material that mimics the bone extracellular matrix. To this aim, this work describes a new method to produce nanostructured collagen-apatite composites on titanium alloy substrate, by combining electrospinning and biomimetic mineralization. The characterization results showed that the obtained mineralized scaffolds have morphological, structural, and chemical compositional features similar to natural bone extracellular matrix. Finally, the topographic distribution of the chemical composition in the mineralized matrix evaluated by Fourier Transform Infrared microspectroscopy demonstrated that the apatite nanocrystals cover the collagen fibers assembled by the electrospinning.

Reactivity of Ubiquinones and Ubiquinols with Free Radicals

The reactivity of quinones 1–4 and of the corresponding quinols 5–8 towards carbon- and oxygen-centred radicals were studied. All quinones bearing at least one nuclear position free, readily react with alkyl and phenyl radicals to afford the alkylated quinones 12–24; however, quinones 1 and 3 reacted with 2-cyano-2-propyl radical to yield products (the mono- and di-ethers 9–11) derived from the attack on the carbonylic oxygen. The reactions carried out on quinones with the benzoyloxy radical led to no reaction products and in the case of Q10, the isoprenic chain also remained unchanged. Quinols 5–8 reacted only with oxygencentred radicals (benzoyloxy and 2-cyano-2-propylperoxy radicals) to give the corresponding quinones. The isoprenic chain of Q10 did not undergo attack even with peroxy radicals. Carbon-centred radicals resulted unable to abstract hydrogen from the studied quinols.

Fourier transform infrared spectrometry investigation of solvent effect on NH and CO stretching modes in N-acylaminopyridines

Abstract Infrared determinations on N-acetyl- and N-benzoylaminopyridines in a set and in mixtures of solvents are reported and discussed in terms of bulk and solute-solvent interactions. Contributes from bonded modes have been characterised and attributed. The nature and the position of the substituents on the pyridine ring and the type of environment markedly influence the structural changes.

The effect of bivalent metal ions on complexes DNA–liposome: a FT-IR study

Abstract Triple complexes of calf thymus DNA with dimyristoylphosphatidylcholine (DMPC) liposome and bivalent metal ions (Me 2+ ) have been studied by Diffuse Reflectance Fourier Infrared Spectroscopy. By comparing spectra with the ones of the binary systems arising by coupling any two of the three components, more insight on A, B, Z conformational changes in DNA, as well as on chain packing, has been obtained.

Fourier transform infrared spectroscopy Part V. Vibrational studies on phenanthroline-perchloric acid complexes

Abstract Infrared spectra of phenanthrolines-perchloric acid hydrogen-bonded complexes are discussed together with x-ray results and theoretical calculations in order to verify the participation of ortho-hydrogens or ortho-methyls of phenanthroline in the complex formation. The role of through-bond and through-space contributions to hydrogen bonding is considered.