Self-assembled nanogels of cholesteryl-modified polysaccharides: Effect of the polysaccharide structure on their association characteristics in the dilute and semidilute regimes
Self-assembled nanogels of cholesteryl-modified polysaccharides: Effect of the polysaccharide structure on their association characteristics in the dilute and semidilute regimes
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DOI：
10.1021/bm070136q
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发表时间：
2007-08-01
影响因子：
6.2
通讯作者：
Akiyoshit, Kazunari
中科院分区：
文献类型：
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作者：
Akiyama, Eri;Morimoto, Nobuyuki;Akiyoshit, Kazunari
通过H-1核磁共振（NMR）光谱、尺寸排阻色谱结合多角度激光散射（SEC-MALLS）、动态光散射（DLS）、原子力显微镜（AFM）、荧光猝灭和荧光去极化测量研究了高度支化多糖甘露聚糖（Mw = 5.2 × 10（4）g/mol）的胆固醇衍生物在稀水溶液中的组装。在稀释状态下，每100个甘露糖单位含有类似1个胆固醇基的胆固醇基甘露聚糖（CHM）形成流体动力学半径（R-H）类似于20 nm的纳米凝胶，含有类似于8个大分子，通过由类似9个胆固醇基组成的疏水性纳米结构域结合在一起。它们的密度（Phi（h）（类似于0.02）显著低于由相同摩尔质量和胆固醇取代水平的线性多糖支链淀粉（CHP）的胆固醇衍生物形成的纳米凝胶的密度（类似于0.16）。在半稀释制度中，CHM纳米凝胶形成了一个大凝胶网络的浓度高于12.5%w/w，而CHP纳米凝胶进行大凝胶化仅高于8.0%w/w的阈值浓度，所揭示的振荡和稳态剪切粘度测量。CHM和CHP的溶液性质的差异反映了它们在分子水平上组装的差异，特别是疏水纳米结构域的大小和数量以及水合水平。它们归因于胆固醇基团的流动性的差异，其本身可以追溯到以下事实：在CHM中，胆固醇基团主要与短的寡甘露吡喃糖支链连接，而在CHP中，它们与聚合物主链连接。我们的研究提供了一种新的手段，纳米工程多糖纳米凝胶，可能会发现独特的生物技术应用。
The assembly of cholesteryl derivatives of the highly branched polysaccharide mannan Mw = (5.2 x 10(4) g/mol) in dilute aqueous solution was investigated by H-1 nuclear magnetic resonance (NMR) spectroscopy, size-exclusion chromatography coupled with multiangle laser scattering (SEC-MALLS), dynamic light scattering (DLS), atomic force microscopy (AFM), fluorescence quenching, and fluorescence depolarization measurements. In the dilute regime, cholesteryl-beating mannans (CHM) containing similar to 1 cholesteryl group per 100 mannopyranose units formed nanogels with a hydrodynamic radius (R-H) of similar to 20 nm containing similar to 8 macromolecules held together via hydrophobic nanodomains consisting of similar to 9 cholesteryl groups. Their density (Phi(h) (similar to 0.02) was significantly lower than the density (similar to 0.16) of nanogels formed by a cholesteryl derivative of the linear polysaccharide pullulan (CHP) of identical molar mass and level of cholesteryl substitution. In the semidilute regime, CHM nanogels formed a macrogel network for concentrations higher than 12.5% w/w, whereas CHP nanogels underwent macrogelation only above a threshold concentration of 8.0% w/w, as revealed by oscillatory and steady-shear viscosity measurements. The differences in the solution properties of CHM and CHP reflect differences in their assembly on the molecular level, in particular, the size and number of hydrophobic nanodomains and the hydration level. They are attributed to differences in the mobility of the cholesteryl groups which, itself, can be traced to the fact that in CHM the cholesteryl groups are predominantly linked to short oligomannopyranose branches, whereas in CHP they are linked to the polymer main chain. Our study provides a novel means to nanoengineer polysaccharide nanogels which may find unique biotechnological applications.