Solid-phase microextraction gas chromatography/mass spectrometry: a new method for species identification of truffles

This study describes a rapid method to identify different truffle species by analysis of their volatile compound fraction using static headspace solid-phase microextraction gas chromatography/mass spectrometry. The volatile organic compounds (VOCs) were extracted using a new 2-cm 50/30 microm DVB/CAR/PDMS fiber placed for 10 min in the headspace of the truffle sample with the vial maintained at 20 degrees C (in a thermostatically controlled analysis room). The mass spectra of the VOC chromatograms were represented as 'fingerprints' of the analysed samples. Next, stepwise factorial discriminant analysis afforded a limited number of characteristic fragment ions that allowed a classification of the truffle species studied. This new method provides an effective approach to rapid quality control and identification of truffle species by analysis of their volatile fraction. Moreover, this method offers the advantage of minimizing thermal, mechanical, and chemical modifications of the truffles, thereby reducing the risk of analytical artifacts.     

Novel Biologically Inspired Collagen Nanofibers Reconstituted by Electrospinning Method

The possibility to prepare bioinspired collagen nanofibers by electrospinning from aqueous suspension of telopeptide-free collagen molecules avoiding both organic solvents and blends with any synthetic and natural polymers has been investigated. The results have highlighted the need for a basic atmosphere between the needle and the ground collector in order to increase the environmental pH during the collagen molecules self-assembly along the electrostatic force lines. Morphological, spectroscopic and calorimetric analyses carried out on the electrospun collagen nanofibers have opened the possibility to take advantage of this new approach in order to prepare an ideal biomimetic reinforcing component of new biomedical and surgical biomaterials.     

Reactive Phenanthrene Derivatives as Markers of Amino Groups in Fluorescence Microscopy of Surface Modified Micro-Zeolite L

Journal of Fluorescence - Two reactive phenanthrene derivatives, 4-(1H phenanthrol [9,10-d] imidazole-2-yl) benzaldehyde (PIB) and 6,9-dimethoxyphenanthro[9,10-c]furan-1,3-dione (PA) with high...     

Calorimetric and Raman investigation of cow’s milk lactoferrin

Lactoferrin (LF), a non-heme iron-binding protein of blood plasma and milk with antioxidant, cariostatic, anticarcinogenic, and anti-inflammatory properties, has been studied by differential scanning calorimetry (DSC) and Raman spectroscopy over a wide pH range (4.0–9.0). Using these two techniques, the modifications in the quantity of iron bounded in the cow’s milk LF and in the secondary structures, as a function of pH and heating, have been evaluated. DSC curves showed higher value of denaturation temperatures and enthalpy changes when LF was saturated with iron (holo-form) than when it was in its unsaturated form (apo-form). The denaturation curves of the protein solutions at pH ≥ 5.5 confirming that LF is a mix of apo- and holo-forms; on the contrary at pH 4.0, the holo-form is practically absent. Spectroscopic investigation showed that, as a function of pH, the content of α-helix increases up to pH 7.4, followed by a small decrease by further pH increase. The β-sheet percentage exhibits the opposite behavior, while the random-coil and turn structures do not change noticeably. In contrast, after heat-induced denaturation, strong variations were observed in the secondary structure, with an evident increase of β-sheet and decrease of the α-helix percentage. Finally, both thermal and spectroscopic analysis pointed out that the structure of cow’s milk LF is strictly sensible to pH variation and it has the highest thermal stability at physiological pH.     

On the interaction between supercritical CO2 and epoxides combining infrared absorption spectroscopy and quantum chemistry calculations

The nature and strength of the interactions occurring between epoxides and CO(2) have been investigated by combining infrared spectroscopy with quantum chemistry calculations. A series of infrared absorption experiments on four model epoxide molecules highly diluted in supercritical CO(2) have been performed at constant temperature T = 40 °C for various CO(2) pressures varying from 1 to 30 MPa. Then, we carried out a theoretical analysis based on quantum chemistry calculations using Density Functional Theory (B3PW91 and CAM-B3LYP) and ab initio (MP2) computational methods. A very good agreement between experimental and calculated vibrational frequency shifts of the epoxide ring vibrations group was obtained using the CAM-B3LYP functional, hence validating the calculated optimized geometries of the epoxide-CO(2) complexes. Whatever the epoxide considered, CO(2) is found to be on average above the oxygen atom of the epoxy ring and interacts with the carbon atom of CO(2) through a Lewis acid-Lewis base type of interaction. The substituents on the epoxide ring are found to influence the stability of the epoxide-CO(2) complexes mainly because of the partial charge on the oxygen atom that is sensitive to the nature of the substituent.     

Determining the structure and mode of action of microbisporicin, a potent lantibiotic active against multiresistant pathogens

Antibiotics blocking bacterial cell wall assembly (beta-lactams and glycopeptides) are facing a challenge from the progressive spread of resistant pathogens. Lantibiotics are promising candidates to alleviate this problem. Microbisporicin, the most potent antibacterial among known comparable lantibiotics, was discovered during a screening applied to uncommon actinomycetes. It is produced by Microbispora sp. as two similarly active and structurally related polypeptides (A1, 2246-Da and A2, 2230-Da) of 24 amino acids linked by 5 intramolecular thioether bridges. Microbisporicin contains two posttranslational modifications that have never been reported previously in lantibiotics: 5-chloro-trypthopan and mono- (in A2) or bis-hydroxylated (in A1) proline. Consistent with screening criteria, microbisporicin selectively blocks peptidoglycan biosynthesis, causing cytoplasmic UDP-linked precursor accumulation. Considering its spectrum of activity and its efficacy in vivo, microbisporicin represents a promising antibiotic to treat emerging infections.