Fujii Shigekatsu, Morita Tomoyuki, Kimura Shunsaku
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Kyoto, Japan.
Bioconjug Chem. 2007 Nov-Dec;18(6):1855-9. doi: 10.1021/bc700159c. Epub 2007 Oct 18.
A novel cyclic octapeptide carrying a fullerene unit and poly(ethylene glycol) at the side chain (cyclo8-C 60 + PEG) was synthesized, and its monolayer formation at the air/water interface and on a substrate was studied. Surface pressure-area per molecule isotherms indicated that cyclo8-C 60 + PEG formed a stable monolayer at the air/water interface. The cyclo8-C 60 + PEG monolayers prepared from various spreading volumes (i.e., from various initial areas per molecule) overlapped nicely on a single curve, suggesting that the molecules were uniformly dispersed on the surface without aggregation of the fullerene units. The uniform dispersibility is due to the scaffold effect of the cyclic peptide unit to keep the fullerene units away from each other. The formed monolayer could be quantitatively transferred onto a solid substrate. UV-vis absorption spectroscopy of the Langmuir-Blodgett (LB) monolayer showed that the electronic structure of the fullerene unit was not affected by the formation of the monolayer. Cyclic voltammetry of the LB monolayer in an aqueous solution containing redox species indicated that the LB monolayer was densely packed. Furthermore, reversible redox peaks attributed to the one-electron reduction of the fullerene unit were observed, showing that the redox property of the fullerene unit was also retained in the monolayer. It is thus concluded that the cyclic peptide is a good candidate as a scaffold for stable monolayer formation at the air/water interface and for intact immobilization of the fullerene moiety onto a substrate.
合成了一种在侧链带有富勒烯单元和聚乙二醇的新型环状八肽（环八 - C60 + PEG），并研究了其在空气/水界面和基底上的单分子层形成情况。分子的表面压力 - 面积等温线表明，环八 - C60 + PEG在空气/水界面形成了稳定的单分子层。由不同铺展体积（即每分子的不同初始面积）制备的环八 - C60 + PEG单分子层在一条曲线上很好地重叠，这表明分子在表面均匀分散，富勒烯单元没有聚集。这种均匀分散性归因于环状肽单元的支架效应，使富勒烯单元彼此远离。形成的单分子层可以定量转移到固体基底上。朗缪尔 - 布洛杰特（LB）单分子层的紫外 - 可见吸收光谱表明，富勒烯单元的电子结构不受单分子层形成的影响。在含有氧化还原物质的水溶液中对LB单分子层进行循环伏安法研究表明，LB单分子层紧密堆积。此外，观察到归因于富勒烯单元单电子还原的可逆氧化还原峰，表明富勒烯单元的氧化还原性质在单分子层中也得以保留。因此可以得出结论，环状肽是在空气/水界面形成稳定单分子层以及将富勒烯部分完整固定在基底上的良好支架候选物。
