Control of Immobilization and Hybridization on DNA Chips by Fluorescence Spectroscopy

A new methodology for the analysis of DNA polymorphisms has been developed using specific oligonucleotide strand arrays bound to a solid silicon support recovered by a thin layer of silica. Arrays of directly synthesized oligonucleotides covalently fixed on Si/SiO₂ wafers have been designed at the macroscopic scale. Using suitable nucleotide-labeled units, the fluorescence emission technique has been used as an experimental control of the molecular network bound to the support and as a method for analyzing the hybridizing abilities of the corresponding oligonucleotide array. Fluorescein has allowed us to control the molecular density of the DNA strand resulting from a complete synthetic growing process. A specific protocol using both complementary and noncomplementary units labeled with two probes, Cy3 and Cy5, was used to distinguish clearly nucleotide units fixed on the array either as hybridized sequences or by the unavoidable adsorption process. The present performance of this fluorescence detection procedure will now be used with a scanning fluorescence device to perform the analysis at the microscopic scale.     

Etude rheologique de gels mixtes de poly(alcool vinylique) et d'alginate de sodium

Snake-cage hydrogels were prepared by the association of poly(vinyl alcohol) (PVA) and sodium alginate. The aim of this work is to study the viscoelastic properties of PVA networks having different molecular weights and trapping alginates of various mannuronate/guluronate ratios, molecular weights and aqueous concentration. The elastic and viscous moduli, G′ and G″, were found to depend on alginate concentration. With the sodium alginate (mannuronate/guluronate =1.78, M̄w=380 000), the elasticity was observed to be independent of the PVA molecular weight in the 7.5% to 10% (w/w) concentration range. Hydrogels elasticity was found to be sodium alginate nature-dependent only in the case of PVA with M̄w =22 000. Moreover, it seems that the viscoelastic parameters G′ and G″ become increasingly insensitive to the nature of sodium alginate as the molecular weight of PVA increases.     

Behavior of 1,1-diphenyl-2,5-dihydrophospholium salts toward bases: Ylide formation or ring opening

Efficient procedures are described leading to pure 3,4-R¹, R²-substituted 1,1-diphenyl-2,5-dihydrophospholium salts (R¹ = R² = CH₃, H; R¹ = CH₃, R² = H). Their behaviors toward bases such as nBuLi and tBuOK in THF or DMSO have been examined. According to the nature of the substituents R¹ and R², the complete monodeprotonation of these salts leads either to the corresponding pure five-membered cyclic ylide (and, in some cases, its prototropic isomer) or to a dienylphosphine resulting from a ring opening. The reactivity of the 3,4-dimethyl-disubstituted salt was especially studied. The corresponding monoylide functions as a good Wittig reagent, allowing stereoselective access to interesting alkadienylphosphine oxides and subsequently to trienes. However, in the presence of alkylating electrophiles, it reacts under an open dienylphosphine form giving rise to P-alkylated phosphonium salts. Nevertheless, this monoylide does not undergo further deprotonation into the corresponding cyclic diylide. Most of the synthetisized derivatives are original. © 1996 John Wiley & Sons, Inc.     

Free glycerol determination in biodiesel samples using palladium nanoparticles modified glassy carbon electrode associated with solid phase extraction

Journal of Solid State Electrochemistry - In this work, we developed a method for the quantification of free glycerol in biodiesel using electrochemical detection and solid phase extraction (SPE)....     

Pickering Emulsions Stabilized with Curcumin-Based Solid Dispersion Particles as Mayonnaise-like Food Sauce Alternatives

Pickering emulsions, which are emulsions stabilized by colloidal particles, are being increasingly positioned as novel strategies to develop innovative food product solutions. In this context, the present work aims to develop Pickering emulsions stabilized by natural-based curcumin-loaded particles produced by the solid dispersion technique as promising mayonnaise-like food sauce alternatives. Two particle formulations (KC1 and KC2) were produced using k-carrageenan as the matrix material and different curcumin contents, then employed in the preparation of three Pickering emulsion formulations comprising different oil fractions (φ) and particle concentrations (KC1 φ 0.4 (4.7%), KC2 φ 0.4 (4.7%) and KC2 φ 0.6 (4.0%)). The creaming index tests accompanied by the optical microscopy analysis evidenced the good stability of the developed products for the tested period of 28 days. The final products were tested concerning color attributes, pH, oxidative stability, textural, and nutritional composition, and compared with two commercial mayonnaises (traditional and light products). Overall, the produced emulsions were characterized by a bright yellow color (an appealing attribute for consumers), an acidic pH (similar to mayonnaise), and a considerably improved oxidative stability, implying a foreseeable longer shelf life. The sauce KC1 φ 0.4 (4.7%) showed a similar texture to the light commercial mayonnaise, being a promising alternative to conventional sauces, holding a low-fat content and potentially added benefits due to the curcumin and virgin olive oil intrinsic properties.     

An N-capping asparagine–lysine–proline (NKP) motif contributes to a hybrid flexible/stable multifunctional peptide scaffold

Structural diversity drives multiple biological activities and mechanisms of action in linear peptides. Here we describe an unusual N-capping asparagine-lysine-proline (NKP) motif that confers a hybrid multifunctional scaffold to a computationally designed peptide (PaDBS1R7). PaDBS1R7 has a shorter α-helix segment than other computationally designed peptides of similar sequence but with key residue substitutions. Although this motif acts as an α-helix breaker in PaDBS1R7, the Asn5 presents exclusive N-capping effects, forming a belt to establish hydrogen bonds for an amphipathic α-helix stabilization. The combination of these different structural profiles was described as a coil/N-cap/α-helix scaffold, which was also observed in diverse computational peptide mutants. Biological studies revealed that all peptides displayed antibacterial activities. However, only PaDBS1R7 displayed anticancer properties, eradicated Pseudomonas aeruginosa biofilms, decreased bacterial counts by 100–1000-fold in vivo, reduced lipopolysaccharide-induced macrophages stress, and stimulated fibroblast migration for wound healing. This study extends our understanding of an N-capping NKP motif to engineering hybrid multifunctional peptide drug candidates with potent anti-infective and immunomodulatory properties.

An unusual N-capping asparagine-lysine-proline (5NKP7) motif yields a coil/N-cap/α-helix multifunctional scaffold in a computer-made peptide selective for anionic surfaces and with anticancer, antibacterial, antibiofilm, anti-infective (in vivo), and immunomodulatory potential.     

Minerals in Pregnancy and Their Impact on Child Growth and Development

During pregnancy, women undergo metabolic and physiological changes, and their needs are higher, to maintain growth and development of the fetus. If the nutritional status of the expectant mother is not satisfactory, some maternal and neonatal complications can occur. In the second and third trimester of pregnancy, there is a reserve of nutrients in the fetus that can be utilized after birth; thereby, children present an accelerated growth in the first years of life, which is a proven response to the available nutrition pattern. However, if such a pattern is insufficient, there will be deficits during development, including brain function. Therefore, despite many recent published works about gestational nutrition, uncertainties still remain on the mechanisms of absorption, distribution, and excretion of micronutrients. Further elucidation is needed to better understand the impacts caused either by deficiency or excess of some micronutrients. Thus, to illustrate the contributions of minerals during prenatal development and in children, iodine, selenium, iron, zinc, calcium, and magnesium were selected. Our study sought to review the consequences related to gestational deficiency of the referred minerals and their impact on growth and development in children born from mothers with such deficiencies     

Corrosion Behavior of Biocompatible Stainless Steels in Physiological Medium for Non‐invasive Diagnosis of Small Fiber Neuropathies Applications

A non‐invasive device based on measurements of electrochemical skin conductance can detect small fiber neuropathy, a sweat gland dysfunction implicated in several diseases. The measurement is related to sweat composition and notably to chloride concentration. To optimize the electrode material, in vitro experiments are performed in mimetic sweat solutions. This work reports on the resistance to pitting corrosion of biocompatible stainless steels (AISI 304L, AISI 430, AISI 430T, D2205) in sweat mimicking electrolyte at pH 7 with variable chloride concentration, to determine the most sensitive material to sweat composition. AISI 430 is promising due to its high sensitivity to chloride concentration variations.     

Electrochromic and electrochemical properties of copolymer films based on EDOT and phenylthiophene derivatives

Journal of Solid State Electrochemistry - The poly(3,4-ethylenedioxythiophene-co-3-phenylthiophene) (P(EDOT-co-3PT)) and poly(3,4-ethylenedioxythiophene-co-3-(4-fluorophenyl)thiophene)...