Functionalized nanocomposite coating of a glass surface for oligonucleotide immobilization

A new type of coating for manufacturing DNA chips was constructed on the basis of an organicinorganic nanocomposite based on the polyvinylbutyral-tetraethoxysilane copolymer. The organosilicon composite was functionalized by introduction of ethanolamine vinyl ether copolymers, which contain amino groups and anchor vinyloxide units capable of reacting with silanol groups of the nanocomposite. The resulting coatings form a film on glass slides with a high surface density of amino groups (up to 700 groups/nm²) suitable for three-dimensional immobilization of oligonucleotides. The use of bifunctional reagents (e.g., phenylene diisothiocyanate) for the attachment of oligonucleotides bearing amino linkers to the amino-containing surface provides an immobilization density of 0.5–1.6 pmol/mm². Immobilization with a higher density (10–12 pmol/mm²) was achieved for attachment to amino-containing glass slides upon the use of oligonucleotides containing a selectively activated terminal phosphate group. The activation of oligonucleotides was carried out with the triphenylphosphine-dithiodipyridine pair in the presence of dimethylaminopyridine N-oxide. The resulting DNA chips were shown to be useful in principle for DNA detection.     

Gas chromatographic separation of PCB atropisomers on cyclodextrin stationary phases

Gas chromatographic study on chiral separation of PCBs was performed in a series of capillary columns coated with 0.1-μm film of modified cyclodextrin (CD) stationary phases. The preparation of columns included the investigation into the effect of the content of cyclodextrin derivative in polysiloxane, the type of polysiloxane and temperature of analysis on the quality of separation and retention of atropisomers of 15 selected PCB congeners. The separation properties towards PCBs of stationary phase heptakis(2,3-di-O-methyl-6-O-tert-butyl-dimethylsilyl)-β-CD dissolved in SE-30, SE-54, and OV-1701, were compared with those of 6-monokis-octamethylene-permethyl-β-CD anchored to polydimethylsiloxane polymer (ChirasilDex column, Chrompack, Middelburg, The Netherlands) and octakis(2,6-di-O-methyl-3-O-pentyl)-γ-CD in OV-1701 (MEGA, Legnano (MI), Italy). The correctness of quantitative enantiomer ratio determination was assesed by splitless analysis of PCBs reference solutions in concentration of 1.25–125 ng/ml (PCBs 45 and 91) and 2.5–250 ng/ml (PCB 95) (the PCB congeners are numbered according to IUPAC). Chirality 10:540–547, 1998. © 1998 Wiley-Liss, Inc.     

Magnetic polysiloxane-polyvinyl alcohol composite as solid-phase in chemiluminescent assays

A polysiloxane and polyvinyl alcohol interpenetrating polymer network was synthesised and its ferromagnetic derivative was used as solid support for antigen covalent immobilisation in chemiluminescent assays. Only 0.625 g of either Trypanosoma cruzi or Schistosoma mansoni antigens immobilized onto the magnetic particles (2.5 mg) were sufficient to detect the correspondent human IgG within a nanogram scale.     

Experiments on in vivo biofilm formation and in vitro adhesion of Candida species on polysiloxane liners

doi:10.1111/j.1741‐2358.2009.00329.x
Experiments on in vivo biofilm formation and in vitro adhesion of Candida species on polysiloxane liners Objectives: Microorganisms may colonise polysiloxane soft liners leading to bio‐deterioration. The aim of this study was to investigate in vitro adhesion and in vivo biofilm formation of Candida species on polysiloxane surfaces. Methods: The materials used in this study were Molloplast B, GC Reline soft, Mollosil Plus, Silagum Comfort and Palapress Vario. The in vitro retention of clinical isolates of Candida albicans to the relining and denture‐base materials by microscopic (scanning electron microscopy, SEM), conventional culturing methods and antimicrobial properties of these materials were studied. Candida found on materials and mucosa following long‐term use were identified and quantified, and biofilms covering the surfaces were investigated by SEM. Results: There was a significant decrease in the number of cells attached in vitro to saliva‐coated surfaces compared with non‐treated surfaces. An oral Candida carriage of 78% was found. Candida albicans, C. glabrata, C. intermedia and C. tropicalis were identified. In vivo biofilm formation on the liners appeared as massive colonisation by microorganisms. Conclusions: The results of the in vitro experiments suggest that salivary film influences early colonisation of different C. albicans strains. The film layer also minimises the differences among different strains. The Candida carriage of these patients was similar to denture‐wearing patients without soft liners.