Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Tokyo, Japan.
Chem Asian J. 2012 Jan 2;7(1):201-6. doi: 10.1002/asia.201100606. Epub 2011 Nov 4.
A nanocylindrical wall structure was obtained by layer-by-layer (LbL) assembly of poly-L-arginine (PLA) and human serum albumin (HSA) and characterized by scanning electron microscopy (SEM), scanning force microscopy (SFM), and cryogenic transmission electron microscopy (cryo-TEM). SEM and SFM measurements of a lyophilized powder of (PLA/HSA)(3) nanotubes yielded images of round, chimney-like architectures with approximately 100 nm wall thickness. Cryo-TEM images of the hydrated sample revealed that the tube walls are composed of densely packed HSA molecules. Moreover, when small-angle X-ray scattering was used to characterize the individual PLA and HSA components in aqueous solutions, maximum diameters of approximately 28 nm and 8 nm were obtained, respectively. These values indicate the minimum thickness of wall layers consisting of PLA and HSA. It can also be concluded from SEM as well as from cryo-TEM images that the protein cylinders are considerably swollen in the presence of water. Furthermore, HSA retains esterase activity if assembled in nanotubes, as indicated by measurements of para-nitrophenyl acetate hydrolysis under semi-physiological conditions (pH 7.4, 22 °C). The enzyme activity parameters (Michaelis constant, K(m), and catalytic constant, k(cat)) were comparable to those of free HSA.
通过层层（LbL）组装聚-L-精氨酸（PLA）和人血清白蛋白（HSA），得到了纳米圆柱形壁结构，并通过扫描电子显微镜（SEM）、扫描力显微镜（SFM）和低温透射电子显微镜（cryo-TEM）进行了表征。对（PLA/HSA）（3）纳米管冻干粉末进行 SEM 和 SFM 测量，得到了具有约 100nm 壁厚的圆形、烟囱状结构的图像。水合样品的 cryo-TEM 图像显示，管壁由紧密堆积的 HSA 分子组成。此外，当使用小角 X 射线散射来表征水溶液中的单个 PLA 和 HSA 成分时，分别获得了约 28nm 和 8nm 的最大直径。这些值表示由 PLA 和 HSA 组成的壁层的最小厚度。SEM 和 cryo-TEM 图像还表明，在存在水的情况下，蛋白质圆柱体明显肿胀。此外，如果在纳米管中组装，HSA 保留酯酶活性，如在半生理条件（pH 7.4，22°C）下测量对硝基苯乙酸酯水解时所表明的。酶活性参数（米氏常数 K(m)和催化常数 k(cat))与游离 HSA 相当。
