Ho Tracey T M, Bremmell Kristen E, Krasowska Marta, Stringer Damien N, Thierry Benjamin, Beattie David A
Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia.
Soft Matter. 2015 Mar 21;11(11):2110-24. doi: 10.1039/c4sm02552k.
Fucoidan is a sulfated polysaccharide that is extracted primarily from seaweed. The polymer contains a natural variation in chemistry based upon the species of seaweed from which it is extracted. We have used two different fucoidans from two different seaweed species (Fucus vesiculosus - FV; and Undaria pinnatifida - UP) as polyanions for the formation of polysaccharide-based polyelectrolyte multilayers (PEMs), to determine if the chemistry of different fucoidans can be chosen to fine-tune the structure of the polymer film. Partially acetylated chitosan was chosen as the polycation for the work, and the presented data illustrate the effect of secondary hydrogen bonding interactions on PEM build-up and properties. Ellipsometry and quartz crystal microbalance with dissipation monitoring (QCM-D) measurements performed during film build-up enabled detailed measurements of layer thickness, adsorbed mass, and the dynamics of the multilayer formation process. High quality atomic force microscopy (AFM) images revealed the differences in morphology of the PEMs formed from the two fucoidans, and allowed for a more direct layer thickness measurement. X-ray photoelectron spectroscopy (XPS) confirmed the chemistry of the films, and an indication of the altered interactions between chitosan and fucoidan with variation in fucoidan type, but also with layer number. Distinct differences were observed between multilayers formed with the two fucoidans, with those constructed using UP having thinner, denser, less hydrated layers than those constructed using FV. These differences are discussed in the context of their varied chemistry, primarily their difference in molecular weight and degree of acetylation.
岩藻依聚糖是一种主要从海藻中提取的硫酸化多糖。该聚合物的化学组成因提取所用海藻的种类而存在天然差异。我们使用了来自两种不同海藻（墨角藻 - FV；裙带菜 - UP）的两种不同岩藻依聚糖作为聚阴离子来形成基于多糖的聚电解质多层膜（PEMs），以确定是否可以选择不同岩藻依聚糖的化学组成来微调聚合物膜的结构。部分乙酰化壳聚糖被选作此项工作的聚阳离子，所呈现的数据说明了二级氢键相互作用对PEMs形成及性质的影响。在膜形成过程中进行的椭偏测量和带耗散监测的石英晶体微天平（QCM-D）测量能够详细测量层厚度、吸附质量以及多层膜形成过程的动力学。高质量的原子力显微镜（AFM）图像揭示了由两种岩藻依聚糖形成的PEMs在形态上的差异，并实现了更直接的层厚度测量。X射线光电子能谱（XPS）证实了膜的化学组成，并表明壳聚糖与岩藻依聚糖之间的相互作用随岩藻依聚糖类型以及层数的变化而改变。观察到用两种岩藻依聚糖形成的多层膜之间存在明显差异，使用UP构建的多层膜比使用FV构建的多层膜具有更薄、更致密、水合程度更低的层。这些差异在其化学组成变化的背景下进行了讨论，主要是它们在分子量和乙酰化程度上的差异。
