Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal.
Langmuir. 2010 Jul 6;26(13):11413-20. doi: 10.1021/la100903j.
Amphiphilic mannan (mannan-C(16)) was synthesized by the Michael addition of hydrophobic 1-hexadecanethiol (C(16)) to hydroxyethyl methacrylated mannan (mannan-HEMA). Mannan-C(16) formed nanosized aggregates in water by self-assembly via the hydrophobic interaction among C(16) molecules as confirmed by hydrogen nuclear magnetic resonance ((1)H NMR), fluorescence spectroscopy, cryo-field emission scanning electron microscopy (cryo-FESEM), and dynamic light scattering (DLS). The mannan-C(16) critical aggregation concentration (cac), calculated by fluorescence spectroscopy with Nile red and pyrene, ranged between 0.04 and 0.02 mg/mL depending on the polymer degree of substitution of C(16) relative to methacrylated groups. Cryo-FESEM micrographs revealed that mannan-C(16) formed irregular spherical macromolecular micelles, in this work designated as nanogels, with diameters ranging between 100 and 500 nm. The influence of the polymer degree of substitution, DS(HEMA) and DS(C(16)), on the nanogel size and zeta potential was studied by DLS at different pH values and ionic strength and as a function of mannan-C(16) and urea concentrations. Under all tested conditions, the nanogel was negatively charged with a zeta potential close to zero. Mannan-C(16) with higher DS(HEMA) and DS(C(16)) values formed larger nanogels and were also less stable over a 6 month storage period and at concentrations close to the cac. When exposed to solutions of different pH and aggressive conditions of ionic strength and urea concentration, the size of mannan-C(16) varied to some extent but was always in the nanoscale range.
两亲性甘露聚糖（甘露聚糖-C（16））是通过疏水性 1-十六烷硫醇（C（16））与羟乙基甲基丙烯酰胺化甘露聚糖（甘露聚糖-HEMA）的迈克尔加成合成的。通过疏水相互作用，甘露聚糖-C（16）在水中自组装形成纳米级聚集体，这一点通过氢核磁共振（1H NMR）、荧光光谱、低温场发射扫描电子显微镜（cryo-FESEM）和动态光散射（DLS）得到证实。通过荧光光谱法用尼罗红和芘计算出的甘露聚糖-C（16）的临界聚集浓度（cac），取决于 C（16）相对于甲基丙烯酰基团的聚合物取代度，范围在 0.04 至 0.02mg/mL 之间。cryo-FESEM 显微照片显示，甘露聚糖-C（16）形成了不规则的球形大分子胶束，在本工作中称为纳米凝胶，直径在 100 至 500nm 之间。通过 DLS 在不同 pH 值和离子强度以及作为甘露聚糖-C（16）和脲浓度的函数下研究了聚合物取代度 DS（HEMA）和 DS（C（16））对纳米凝胶尺寸和 zeta 电位的影响。在所有测试条件下，纳米凝胶带负电荷，zeta 电位接近零。具有较高 DS（HEMA）和 DS（C（16））值的甘露聚糖-C（16）形成较大的纳米凝胶，并且在 6 个月的储存期内以及在接近 cac 的浓度下也不太稳定。当暴露于不同 pH 值的溶液和离子强度和脲浓度的苛刻条件下时，甘露聚糖-C（16）的尺寸在一定程度上有所变化，但始终处于纳米级范围。
