Using particle tracking to probe the local dynamics of barley 尾-glucan solutions upon gelation
- 作者：Thomas Moschakis ; tmoschak@agro.auth.gr ; Athina Lazaridou ; Costas G. Biliaderis
- 关键词：尾-Glucans ; Particle tracking microrheology ; Gelation ; Microstructure
- 刊名：Journal of Colloid and Interface Science
- 出版年：2012
- 期刊代码：125_00219797
- 类别：ch
- 出版时间：1 June, 2012
- 卷：375
- 期：1
- 页码：50-59
- 文件大小：2046 K
摘要
The sol-gel transition of aqueous barley 尾-glucan solutions which undergo gelation with ageing has been studied by conventional bulk rheology, phase contrast microscopy and particle tracking microrheology. Characterisation of the primary structure of the 尾-glucan isolate was carried out by enzymic methods and HPLC. The Brownian diffusion of fluorescent microspheres (0.75 渭m diameter, carboxylate-coated particles) was used to probe the spatial mechanical properties of the gelling systems at the scale of microns; the potential use of passive particle tracking to study biopolymer gelling systems that present spatial heterogeneities is thus explored. For the 尾-glucan gels cured at 25 掳C both microrheology and bulk rheology revealed that with increasing the polysaccharide concentration the gelation time decreased, while the gelation rate and gel strength of the barley 尾-glucan gels increased. The particle tracking method had higher sensitivity and could map molecular ordering and structural heterogeneities in the evolving polysaccharide network at a micro-level. That is, different size pores were generated upon ageing with regions of depleted or less amount of 尾-glucan molecules. Furthermore, this method could detect changes in the fine structure of the system before such events can be registered by bulk rheological measurements; i.e. microheterogeneity and aggregation of 尾-glucan chains were revealed by particle tracking at earlier temporal stages of the experiment.