A method is presented to prevent microbial adhesion to solid surfaces exploiting the unique properties of polymer brushes. Polyacrylamide (PAAm) brushes were grown from silicon wafers by atom transfer radical polymerization (ATRP) using a three-step reaction procedure consisting of immobilization of a coupling agent γ-aminopropyltriethoxysilane, anchoring of an ATRP initiator 4-(chloromethyl)benzoyl chloride, and controlled radical polymerization of acrylamide. The surfaces were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ellipsometry, and contact-angle measurements. The calculated grafting density pointed to the presence of a dense and homogeneous polymer brush. Initial deposition rates, adhesion after 4 h, and detachment of two bacterial strains (Staphylococcus aureus ATCC 12600 and Streptococcus salivarius GB 24/9) and one yeast strain (Candida albicans GB 1/2) to both PAAm-coated and untreated silicon surfaces were investigated in a parallel plate flow chamber. A high reduction (70−92%) in microbial adhesion to the surface-grafted PAAm brush was observed, as compared with untreated silicon surfaces. Application of the proposed grafting method to silicone rubbers may offer great potential to prevent biomaterials-centered infection of implants.

The present paper gives an account of the results of a systematic investigation on the fungicidal It is shown that among these compounds one structural Within this type the influence on theThe toxicity of organo-tin compounds towards some other organisms is mentioned briefly. The final section deals with possibilities for practical applications of organo-tin compounds From the results of laboratory tests the preservation properties of organo-tin compounds.type in particular exhibits a very high fungicidal activity.activity of the nature of the various groups linked to tin has been investigated.as a consequence of their biocidal properties. of wood seems the most promising possibility.

The preparation, according to t he slightly modified procedure of Finholt et al., of the following organo-tin hydrides is described: tri ethyltin hydride, tri-n-propyltin hydride, tri-n-butyltin hydride, triphenyltin hydride, di-n-propyltin dihydride, di-n-butyltin dihydride, diphenyltin dihydride and n-butyltin trihydride.In addition, the preparation of the intermediate n-butyltin trichloride is described.

The reversible manipulation of the helix screw sense in surface-grafted poly(β-phenethyl-L-aspartate) (PPELA) films by means of external stimuli was investigated. Ringopening polymerization of β-phenethyl-L-aspartate N-carboxyanhydride initiated from primary amino-functionalized silicon and quartz substrates results in surfacegrafted PPELA films in which the end-grafted polypeptide chains have a right-handed R-helical conformation. Upon annealing of the film at 150 °C for 30 min, a helix screw sense inversion takes place and the grafted chains adopt a left-handed π-helical conformation. In the solid state, this left-handed π-helical form is completely stable and cannot be changed by reheating and/or cooling. Upon immersion of the annealed grafted film in chloroform or other helicogenic solvents, the grafted polypeptide chains completely revert to their original right-handed R-helical form. Successive annealing and solvent treatment steps show that this helix sense inversion cycle can be repeated many times.

Using a chemical cross-linking procedure, surface-grafted polyglutamate films with a permanently perpendicular helix orientation were prepared. A surface-grafted alpha-helical polyglutamate film containing polymerizable side groups was synthesized by ring-opening terpolymerization of 50 molar% gamma-methyl-L-glutamate N-carboxyanhydride (NCA), 30% gamma-stearyl-L-glutamate NCA and 20% gamma-4-vinylbenzyl-L-glutamate NCA initiated from a silicon substrate functionalized with primary amino groups. The average tilt angle of the end-grafted helices in this film is approximately 66 degrees , indicating a nearly parallel helix orientation with respect to the substrate surface. After swelling of the grafted terpolyglutamate film in stearyl methacrylate and subsequent radical cross-linking, the average helix tilt angle decreases to about 11 degrees, indicating an almost perpendicular helix orientation. The film thickness increases accordingly from 151 A before to approximately 390 A after cross-linking. Extensive solvent treatment of the cross-linked film shows that the perpendicular helix orientation is permanent.

The preparation of a number of unsymmetrical tri‐n‐alkyltin acetates is described. From the antifungal test results of these compounds it appears that a single rule governs the activity of both symmetrical and unsymmetrical tri‐n‐alkyltin acetates, namely that it is the total number of carbon atoms present in the alkyl groups, rather than the nature of the groups, which governs the fungitoxicity of the compounds; this is greatest for a total of 9–12 carbon atoms.

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Es wird eine Übersicht über den gegenwärtigen Stand der Organozinn-Forschung gegeben. Zahlreiche neue, teilweise hier erstmals mitgeteilte Synthesen erlauben es, eine Fülle interessanter Verbindungen herzustellen. Auf einige neue Anwendungsmöglichkeiten von bestimmten Typen von Organozinn-Verbindungen wird hingewiesen. Besonders aussichtsreich erscheint die Verwendung im Pflanzenschutz.Einleitung Die Kohlenstoff-Verbindungen der Metalle der vierten Hauptgruppe des Periodensystems müssen zu den stabilsten Organometall-Verbindungen überhaupt gerechnet werden. In diesen metallorganischen Verbindungen ist die Metall-Kohlenstoff-Bindung verhältnismäßig inert, sowohl gegen hydrolysierende als gegen oxydierende Einflüsse. Dementsprechend sind, im Gegensatz zu den meisten anderen metallorganischen Verbindungen, die organischen Derivate der Elemente der vierten Hauptgruppe zu Alkylierungen oder Arylierungen nur wenig geeignet.Diese hohe Stabilität hängt zusammen mit der in dieser Hauptgruppe immer wieder auftretenden Hybridisierung der s-und der p-Elektronenbahnen in der Valenzhülle zu der tetraedrischen sp 3 -Konfiguration. Hierdurch haben in dieser Hauptgruppe alle Verbindungen vom Typus R 4 M in großen Zügen übereinstimmende physikalische und che-*) Erweiterte Fassung eines Vortrags, gehalten am 28. November 1957 auf der Vortragstagung "Organozinn-Verbindungen des Zinn-Informationsbüros (Düsseldorf) in Frankfurt/Main.