Mariana Pinteala

Binding fullerenol c 60 (Oh) 24 to dsDNA

The first C60(OH)24-DNA complex and its fluorescence enhancement is reported. The enhanced fluorescence intensity of fullerenol C60(OH)24 is in proportion to the concentration of DNA in the range of 1 × 10−9 to 8 × 10−5 molL−1 and the detection limit was 1.3 ng mL−1. Fullerenol C60(OH)24 binds significantly to the phosphate backbone of native dsDNA and to base-pairs within the major groove of sodium salt of dsDNA.

Synthesis and photocrosslinking of benzyl acrylate substituted polydimethylsiloxanes

This article deals with the synthesis of polydimethylsiloxanes (PDMSs) substituted with chain or end benzyl acrylate groups by the hydrosilation of appropriate hydro-siloxanes, followed by phase transfer catalysed reaction of chloromethylated aromatic groups with the sodium salt of acrylic acid. Differential scanning photocalorimetry (DPC) was used to study the crosslinking behaviour of the mentioned functional PDMSs in the presence of different photoinitiators. The reaction rate, the final conversion and the inhibition period characterizing the crosslinking were found to be dependent on reaction atmosphere, light intensity, nature and concentration of photoinitiator and on polymer functional groups content.

Multilayer lectin-glyconanoparticles architectures for QCM enhanced detection of sugar-protein interaction.

Multivalent biorecognition of lectin layers by glyconanoparticle sugar-clusters has been used to generate multilayer nanoplatform architectures in a QCM sensing setup.

Theoretical study on β-cyclodextrin inclusion complexes with propiconazole and protonated propiconazole.

Summary The synthesis of the β-cyclodextrin/propiconazole nitrate inclusion complex and the advantages of the encapsulation of this drug were recently reported, but the experimental data only partially revealed the structure of the supramolecular complex due to the limitations in understanding the intermolecular association mechanism. The present work describes the equilibrium molecular geometries of β-cyclodextrin/propiconazole and β-cyclodextrin/protonated propiconazole, established by the AM1 and PM3 semi-empirical methods. The affinity between different parts of the guest molecule and the cyclodextrin cavity was studied considering that propiconazole possesses three residues able to be included into the host cavity through primary or secondary hydroxyl rims. The results have revealed that the most stable complex is formed when the azole residue of the propiconazole enters the cavity of the cyclodextrin through the narrow hydroxyl’s rim.

Synthesis and characterisation of thermomesogenic polysiloxanes with 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione units in the main chain

The synthesis of the first two liquid crystalline polysiloxanes bearing 3,6-diaryl-2,5-dihydropyrrolo-[3,4-c]pyrrole-1,4-dione units in their main chain are described. Investigations on their thermotropic phase behaviour by polarising microscopy reveal nematic or smectic enantiotropic phases, respectively.

Hybrid fullerene conjugates as vectors for DNA cell-delivery

The present study reports fullerene conjugates that act as efficient binders of double stranded DNA (dsDNA) into cytofriendly polyplexes. The conjugates are designed to generate dendrimeric structures, having C60 as the core and bearing linear or branched PEI and polyethyleneglycol (PEG) arms (∼2 kDa). Simple and reproducible synthesis pathways provided C60-PEI and C60-PEG-PEI conjugates. They were able to bind linear and plasmidic dsDNA and they form particulate polyplexes of 50 to 200 nm in diameter. The resulted polyplexes toggle between the anionic and cationic state at nitrogen to phosphorous ratios (N/P) of about 5, as revealed by their zeta potential and became colloidally stable at N/P ratios above 10, as determined by atomic force microscopy (AFM). They are electrophoretically unbreakable starting with N/P ratios of 3 and of 5 when salmon sperm DNA and pEYFP-C1 plasmid, respectively are loaded. Both C60-PEI·pEYFP and C60-PEG-PEI·pEYFP polyplexes are non-cytotoxic against HEK 293T cells in culture and exhibit transfection efficiency better than 25% (N/P ratios above 20) and 6% (N/P ratios above 60) respectively, measured by flow cytometry. For comparison, the commercial SuperFect® from Qiagen (positive control) was able to provide an efficiency of 15-20%, under similar conditions. Moreover, the C60-PEG-PEI conjugate is as performant as the positive control in terms of expression of EYFP reporter gene in cultured cells and exhibited high cytocompatibility, determining cell proliferation up to 200%. Our study proved that C60-PEG-PEI is effective vector for DNA delivery being, in addition, easily synthesizable, practically non-cytotoxic and as efficient the commercially available transfection tools.

Dual crosslinked iminoboronate-chitosan hydrogels with strong antifungal activity against Candida planktonic yeasts and biofilms.

Chitosan based hydrogels are a class of cross-linked materials intensely studied for their biomedical, industrial and environmental application, but their biomedical use is limited because of the toxicity of different organic crosslinkers. To overcome this disadvantage, a new strategy to produce supramolecular chitosan hydrogels using low molecular weight compounds able to form covalent linkages and H-bonds to give a dual crosslinking is proposed. For this purpose we used 2-formylphenylboronic acid, which brings the advantage of imine stabilization via iminoboronate formation and potential antifungal activity due to the presence of boric acid residue. FTIR and NMR spectroscopy indicated that the gelling process took place by chemo-physical crosslinking forming a dual iminoboronate-chitosan network. Further, X-ray diffraction demonstrated a three-dimensional nanostructuring of the iminoboronate network with consequences on the micrometer-scale morphology and on the improvement of mechanical properties, as demonstrated by SEM and rheological investigation. The hydrogels proved strong antifungal activity against Candida planktonic yeasts and biofilms, promising to be a friendly treatment of the recurrent vulvovaginitis infections.

Functional Polysiloxanes. 3. Reaction of 1,3-Bis(3-Glycidoxypropyl)-1,1,3,3-Tetramethyldisiloxane with Amino Compounds

Abstract Novel organofunctional disiloxanes were obtained by the reaction between 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane and aromatic amino compounds, i.e., aniline and p-aminobenzoic acid. The influence of the reaction conditions on the structure of the resulting compounds was followed.

Polyrotaxanes composed of β-cyclodextrin and polydimethylsiloxanes: synthesis, morphology and thermal behavior

Epoxy-terminated polydimethylsiloxanes (E-PDMSs) of different molecular weight M n were proved to undergo inclusion complexation into the inner cavity of β-cyclodextrin (β-CD), resulting in polyrotaxanes (PRots). The dethreading of the macrocycle was prevented by blocking the siloxane chain with a bulky substituent derived from 4-aminophenyltriphenyl methane (APhTPhM). As revealed by thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy (SEM), wide-angle X-ray diffraction and statistical analysis of SEM images, the thermal properties and the morphology of polyrotoxanes are dependent upon M n, β-CD/E-PDMS molar ratio and the presence of free β-CD in the complexes.

Design and synthesis of a new polymer network containing pendant spiroacetal moieties

The present work describes the synthesis, properties, and sensitive behavior of a set of copolymers based on itaconic anhydride with different molar ratios of 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5] undecane prepared through radical polymerization process, in the presence of 2,2-azobisisobutyronitrile as initiator. The chemical structure of the prepared copolymers was confirmed by FTIR and 1H NMR. The macromolecular compounds were characterized from the viewpoint of their thermal stability. The sensitivity of the new structures was evaluated by determining the hydrodynamic radius in interdependence with environmental conditions, and rheological properties were studied in terms of shear rate and viscosity. The versatility and untapped potential of these stimuli-sensitive polymeric systems generated by both comonomers – network formation, biodegradability and biocompatibility, gel formation capacity, binding properties, amphilicity, good oxidative and thermal stability, good films formers, acid pH sensitivity, the possibilities to modify the anhydride ring through suitably reactions – makes them promising agents for pharmaceutical delivery systems or support for bioactive compounds, among other applications.