Evidence for Singlet-Oxygen Generation and Biocidal Activity in Photoresponsive Metallic Nitride Fullerene-Polymer Adhesive Films
The adhesive properties, as measured by bulk tack analysis, are found to decrease in blends of isomerically pure Sc(3)N@I(h)-C(80) metallic nitride fullerene (MNF) and polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer pressure-sensitive adhesive under white light irradiation in air. The reduction of tack is attributed to the in situ generation Of (1)O(2) and subsequent photooxidative cross-linking of the adhesive film. Comparisons are drawn to classical fullerenes C(60) and C(70) for this process. This work represents the first demonstration of (1)O(2) generating ability in the general class of MNFs (M(3)N@C(80)). Additional support is provided for the sensitizing ability Of Sc(3)N@I(h)-C(80) through the successful photooxygenation of 2-methyl-2-butene to its allylic hydroperoxides in benzene-d(6) under irradiation at 420 nm, a process that occurs at a rate comparable to that Of C(60). Photooxygenation of 2-methyl-2-butene is found to be influenced by the fullerene sensitizer concentration and O(2) flow rate. Molar extinction coefficients are reported for Sc(3)N@I(h)-C(80) at 420 and 536 nm. Evaluation of the potential antimicrobial activity of films prepared in this study stemming from the in situ generation of (1)O(2) led to an observed 1 log kill for select Gram-positive and Gram-negative bacteria.