Interactions of Cinnamycin-Immobilized Gold Nanorods with Biomimetic Membranes

The behavior of the cinnamycin immobilized on the gold nanorod(AuNR) was investigated using surface plasmon resonance(SPR). For the comparison of the immobilized cinnamycin, the study for the free cinnamycin was also conducted. The bilayer was fabricated by tethering 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanols on a gold surface to form a monolayer and then using liposomes to adsorb an outer layer on the tethered-monolayer. The liposomes were prepared with a desired ratio of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine to 1,2-dioleoyl-sn-glycero-3-phosphocholine (0:100, 5:95, 10:90, 20:80, and 30:70). After the cinnamycin was injected on the bilayers, the specific binding between the cinnamycin and the bilayer was monitored with SPR. The inclusion of DOPE in the outer layer clearly led to the specific binding of the cinnamycin on the membranes. Specifically, the binding behavior of the immobilized was different from that of the free. For the free cinnamycin, the binding amount of cinnamycin at 10% was two times more than that at 5%. For the immobilized cinnamycin, the amounts were identical for both compositions. However, the rate was much faster for the immobilized cinnamycin at 10% than 5%, compared to that for the free at both compositions. This difference was attributed to the mean-molecular areas of the cinnamycin and DOPE, and the steric effect of the AuNR. For the effects of the heat and storage, the immobilized enzyme showed less decrease in the relative binding amount than the free one.