Biomimetic droplets for artificial engagement of living cell surface receptors: the specific case of the T-cell

Liquid colloids, in the form of droplets grafted with specific biomolecules, are emerging as potential biomimetic systems. Here we show for the first time the possibility of forming hybrid conjugates between an advanced living cell model, the T-cell of the Jurkat cell line, and a specifically grafted droplet. Using T-cells expressing a fluorescent chimeric protein associated with the TCR/CD3 complex and fluorescent ligand-grafted droplets, we demonstrate formation of an interfacial contact concentrated in linking molecules, the morphology and dynamics of which strongly depend on the targeted receptor. The sequence of events ranges from the initial concentration of molecules following an unbound molecule gradient to active actin-driven spreading and fragmentation of the contact, ending with droplet internalization. We observed synchronized colocalization of receptors and ligands driven by cell dynamics and closely mirrored by the droplet interface. Using intracellular calcium probe Fura-2, we also showed that the cell/droplet interaction can trigger the T-cell signaling cascade. By examining molecular dynamics using FRAP measurements, we observed a nearly frozen cell droplet joining interface. Taken together, our results point to liquid colloids as promising new tools both for probing cell surface interactions and receptor dynamics and for manipulating biological cell functions.     

Use of 1,10-phenanthroline in diiron dithiolate derivatives related to the [Fe-Fe] hydrogenase active site

Treatment of [Fe(2)(micro-pdt)(CO)(6)] (pdt = S(CH(2))(3)S) with 1,10-phenanthroline (phen) in refluxing toluene affords the asymmetric complex [Fe(2)(micro-pdt)(CO)(4)(phen)] (1); the protonation of with HBF(4).OEt(2) in CD(2)Cl(2) at 203 K has been monitored by (1)H NMR.     

On the transition moment of the CO2 40°1II-00°0 band near 7740 cm-1

Using intensity measurements on the CO₂ 40°1_II-00°0 band obtained by Valero and Boese, we have expanded the F(m)-factor for the parallel band by using the Herman-Wallis formula. We have calculated the transition moment and determined the coefficients in the expansion of F(m).     

Synthesis and characterization of functional fluorinated telomers

The synthesis and characterizations of fluorinated telomers based on vinylidene fluoride (VDF) by iodine transfer polymerization (ITP) are presented. These telomers were prepared in the presence of ω‐iodoperfluorinated functional chain transfer agents, C₆F₁₃I or C₄F₉I. ITPs were initiated by thermal decomposition of bis(4‐tert‐butylcyclohexyl) peroxydicarbonate (BBCHPDC), in solution (in the presence of acetonitrile). The obtained telomers were characterized by different analyses such as elemental analyses, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy, size exclusion chromatography, X‐ray diffraction (XRD), and finally by thermal analyses such as differential scanning calorimetry (DSC) and thermogravimetric analyses. These technical analyses enabled one to assess their chemical structures, various thermal properties, and their crystalline forms. The assignments of the characteristic signals obtained by ¹⁹F NMR spectroscopy enabled one to calculate the average degrees of polymerization (DPn) and percentages of ? CH₂CF₂I end group functionalities that depend on the initiator and the fractionation process after reaction. A good control of polymerization was shown by the absence of reversed ? CH₂CF₂? CF₂CH₂? (VDF–VDF dyads) and narrow polydispersity indices (<1.2). The XRD and DSC evidenced the influence of the chain length of the telomers on the crystallinity rate (>70%) and indicated two crystalline forms, α and β, that depended on DPn values. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

The Molecular Complexes of Calix[4]resorcinolarene with Diglycidylmethyl Phosphonate

The formation of strong molecular complexes of calix[4]recorcinolarene with the polyfunctional phosphoorganic compound diglycidylmethyl phosphonate was observed in organic media. Complexes of different compositions were obtained with the ratio of the initial reagents of 1 : 1 and 1 : 4. Three complexes were isolated and characterized by elemental analysis; their ¹H and ¹³C NMR spectroscopic parameters are also discussed.     

LC/ESI-MS n and 1H HR-MAS NMR analytical methods as useful taxonomical tools within the genus Cystoseira C. Agardh (Fucales; Phaeophyceae)

Species of the genus Cystoseira are particularly hard to discriminate, due to the complexity of their morphology, which can be influenced by their phenological state and ecological parameters. Our study emphasized on the relevance of two kinds of analytical tools, (1) LC/ESI-MSⁿ and (2) ¹H HR-MAS NMR, also called in vivo NMR, to identify Cystoseira specimens at the specific level and discuss their taxonomy. For these analyses, samples were collected at several locations in Brittany (France), where Cystoseira baccata, C. foeniculacea, C. humilis, C. nodicaulis and C. tamariscifolia were previously reported. To validate our chemical procedure, the sequence of the ITS2 has been obtained for each species to investigate their phylogenetic relationships at a molecular level. Our study highlighted the consistency of the two physico-chemical methods, compared to “classical” molecular approach, in studying taxonomy within the genus Cystoseira. Especially, LC/ESI-MSⁿ and phylogenetic analyses converged into the discrimination of two taxonomical groups among the 5 species. The occurrence of some specific signals in the ¹H HR-MAS NMR spectra and/or some characteristic chemical compounds during LC/ESI-MSⁿ analysis could be regarded as discriminating factors. LC/ESI-MSⁿ and ¹H HR-MAS NMR turned out to be two relevant and innovative techniques to discriminate taxonomically this complex genus.     

Synthesis of 2-(N-Benzylpyrrolyl)-benzimidazoles Using Polyphosphoric Acid Prompted Cyclocondensation

Synthesis of a series of 2-substituted benzimidazoles was carried out for screening anti-inflammatory activities. 2-(N-benzylpyrrolyl)-benzimidazoles 9a-k were synthesized from N-benzyl-2-pyrrole carboxylic acids 8a-d and 4-substituted-1,2-phenylenediamines by cyclocondensation utilizing polyphosphoric acid (PPA) as condensing agent. The N-benzyl-2-pyrrole carboxylic acids were prepared by standard method of N-benzylation of 2-pyrrole carboxylate using NaH/DMF and appropriately substituted benzyl halides followed by alkaline hydrolysis.