A DSC and Raman Study of the Interaction between Tricresyl Phosphates (TCP) and Phospholipid Liposomes

This paper reports on the DSC and Raman measurements of hydrated multilamellar dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) liposomes in the presence of raw tricresyl phosphates (TCP) and pure tri-o-cresyl phosphate (TOCP). The results on TCP/DMPC and TOCP/DMPC liposomes showed no significant differences. Both the Tm decrease and DT1/2 increase, obtained by increasing the relative amount of TCP with respect to liposomes, suggested that the hydrophobic core is strongly affected by the presence of TCP molecules, whose deep penetration into the bilayer is prevented by the polar interactions between the P=O group of the TCP molecules and the polar head on DMPC. On the contrary, the TCP/DMPE and TOCP/DMPE systems showed a phase segregation that takes place in the presence of a very small amount of TCP, and occurs somewhat more easily in the presence of TOCP than of raw TCP. Both TCP and TOCP molecules interact mainly with the outer face of the bilayer and only secondly affect the hydrophobic core of membranes

Lipid geometrical isomerism: from chemistry to biology and diagnostics.

Lipidomics, the discipline regarding chemical and metabolic lipid fates in living organisms, has brought about a successful innovation to lipid research. Expansion of trans lipid research can be easily foreseen in analytics, chemical mechanisms, liposome and oil technology, lipidomics, and diagnostics. Innovative fields can also include the design of molecular switches, taking advantage of the different sensitivity of trans- and cis-containing membranes to physical and chemical stimuli, as well as the determination of biological and pharmacological strategies based on the tunable molecular interactions produced by the exchange of the natural cis with the unnatural trans geometry. The presence of trans lipids in membranes also has a profound influence on temperature sensitivity as tested by insertion of a probe sensitive to the lipid environment, such as cis-parinaric acid, using accurate stopped-flow fluorescence measurements

Train-the-trainer booklet bioeconomy and the UrBioFuture experience

Objective of this training is to bring your attention, as educators, to the importance of the bioindustry and the opportunities that it creates for the young people. In this booklet we will share with you tailored made educational and multimedia materials so you can use it in your classes and become the Ambassadors of UrBioFuture Experience

Structural Lesions of Proteins Connected to Lipid Membrane Damages Caused by Radical Stress: Assessment by Biomimetic Systems and Raman Spectroscopy

Model systems constituted by proteins and unsaturated lipid vesicles were used to gain more insight into the effects of the propagation of an initial radical damage on protein to the lipid compartment. The latter is based on liposome technology and allows measuring the trans unsaturated fatty acid content as a result of free radical stress on proteins. Two kinds of sulfu rcontaining proteins were chosen to connect their chemical reactivity with membrane lipid transformation, serum albumins and metallothioneins. Biomimetic systems based on radiation chemistry were used to mimic the protein exposure to different kinds of free radical stress and Raman spectroscopy to shed light on protein structural changes caused by the free radical attack. Among the amino acid residues, Cys is one of the most sensitive residues towards the attack of free radicals, thus suggesting that metal-Cys clusters are good interceptors of reactive species in metallothioneins, together with disulfides moieties in serum albumins. Met is another important site of the attack, in particular under reductive conditions. Tyr and Phe are sensitive to radical stress too, leading to electron transfer reactions or radical-induced modifications of their structures. Finally, modifications in protein folding take place depending on reactive species attacking the protein

Biomimetic Models of Radical Stress and Related Biomarkers

The biological consequences of free radical production is the central subject of a very lively scientific debate, focusing on the estimation of the type and extent of damage, as well as the efficiency of the protective and repair systems. When studying free radical based chemical mechanisms, it is very important to establish biomimetic models, which allow the experiments to be performed in a simplified environment, but suitably designed to be in strict connection with cellular conditions. The biomimetic modeling approach has been coupled with physical organic chemistry methodologies and knowledge of free radical reactivity. Molecular basis of important processes have been identified, building up molecular libraries of products concerning unsaturated lipids, sulfur-containing proteins and nucleic acids, to be developed as biomarkers. Ongoing projects in our group deal with lipidomics, genomics and proteomics of free radical stress and some examples will be described

Biomimetic Chemistry on Tandem Protein/Lipid Damages under Reductive Radical Stress

The study of radical stress in the biological environment needs a comprehensive vision of all possible reactive species and their mechanisms. Among them, reductive stress is evaluated for its selective target of sulfur-containing compounds. The selective attack of reducing species like H• atoms or eaq?/H+ to sulfur-containing amino acid residues has been proved in different substrates, peptides and proteins. The transformations include methionine to ?-aminobutyric acid and cysteine/cystine residues to alanine, as recognized in several sequences so far, such as RNase A, lysozyme, Met-enkephalin, amyloid ?-peptide and metallothioneins. The amino acid desulfurization is accompanied by the formation of low-molecular-weight sulfur-centered radicals that may cause geometrical cis–trans isomerization of unsaturated fatty acid residues in lipid bilayer. Thus, tandem protein/lipid damage is accomplished. Progress in research has given us a more comprehensive overview of the protein modifications and their roles, and the chemical biology approach will make its vital contribution to the study of free radical reactions, linking chemistry to biology and medicine

Emerging imaging techniques applied to chemical-physical and spatial characterisation of biochar

Biochar, a carbon-rich material produced through the pyrolysis of agricultural biomasses (e.g. crop residues, wood biomass and animal litter) and solid wastes, represents a win-win solution for a rationale waste management. A sustainable biochar use requires an identification and standardization of certain qualities and characteristics because chemical, structural and morphological properties depend on burned matrix, pyrolysis conditions, rate of heating-slow versus fast pyrolysis and the duration of charring. The aim of this work was to better identify the physical-chemical and spatial characteristics of biochars by applying two emerging imagining techniques, the 2D automated optical image analysis and hyperspectral enhanced dark-field microscopy (EDFM), in addition to SEM analysis. The biochars were obtained from three different biomasses: vineyard pruning residues (PR), anaerobic cattle digestate (CD) and litter poultry (PL) at two pyrolysis temperatures (350 and 550C). 2D optical image analysis confirmed that the biomass composition and the pyrolysis temperature mainly influenced the different physical structures of the biochar samples. In particular, PR biochar was characterized by broken and fragmented structure with irregular and rough particle surface, completely different by the original PR wood cell. This result was also supported by SEM micrograph. The EDFM imaging analysis evidenced the disappearance of four endmembers due to the thermal degradation of PR vegetal products, composed primarily by hemicellulose, cellulose and lignin. As regards the biochar from PL, the pyrolysis produced smaller particles with regular and smoother surface compared to the original biomass. This phenomenon was more evident after the treatment at the highest temperature. The great susceptibility to the temperature might depend on minor morphological homogeneity of PL in comparison with other biomasses. Finally, beyond circularity and convexity increasing after CD charring, pixel intensity decreased by increasing the temperature, indicating changes in chemical composition. Indeed, CD biochar produced at 550C exhibited the most regular particle size and shape, probably due to the formation of semi-crystalline aggregates. In conclusion, 2D automated optical image analysis and hyperspectral enhanced dark-field microscopy are resulted to be effective in determining the chemical-physical properties of biochar particles, and so they can be considered as promising imaging techniques in this filed. More investigations are need in order to validate both techniques on biochars from different origin

Raman spectroscopy: a useful tool to probe protein structural changes

Raman spectroscopy has become a versatile tool in protein science and biotechnology thanks to the improved instrument sensitivity which has increased the signal-to-noise ratio. Thus, this technique can be successfully used for determination of protein secondary structure, identification of metal coordination sites, hydrogen bonding, oxidation state and local environments of selected residues (i.e. Cys, Tyr, Trp), protein-ligand and -DNA interactions, etc. The advantages of this spectroscopic technique are its extreme sensitivity to changes in structure and molecular interaction and its non-destructive nature. In particular, in our lab, Raman spectroscopy has been recently used for obtaining structural information on changes induced by different stimuli: \u2022 thermal aggregation: beta-lactoglobulin and bovine serum albumin; \u2022 presence of metal ions: metallothioneins; \u2022 adsorption of biomedical devices: self-assembling peptides; \u2022 damages induced by radical stress: human serum albumin; \u2022 thermal or chemical denaturation: lysozime

Stimulated Adsorption of Humic Acids on Capped Plasmonic Ag Nanoparticles Investigated by Surface-Enhanced Optical Techniques

The adsorption of humic substances on Ag nanoparticles (AgNPs) is of crucial environmental importance and determines the toxicity of these NPs and the structure of adsorbed organic matter. In this work, the adsorption of two standard soil and leonardite International Humic Substances Society humic acids was studied on AgNPs of different sizes, shapes (spherical and star-like), and interfacial chemical compositions. Surface-enhanced optical (Raman and fluorescence) spectroscopies were used to follow the specific chemical groups involved in this adsorption. By means of the latter optical techniques, information regarding the binding mechanism and the macromolecular aggregation can be deduced. The influence of the surface chemical composition induced by the different functionalizations of the interfaces of these NPs is highly important regarding the chemical interactions of these complex organic macromolecules. The surface functionalization with positively charged alkyl diamines led to a large increase in the adsorption as well as a strong structural rearrangement of the macromolecule once adsorbed onto the surface