Water is a common medium and looks simple, yet its interaction mechanisms with molecules and materials are very complicated. Therefore, intermolecular interactions of load-bearing polysaccharides with water determine the structure and properties of polysaccharides in aqueous systems. In this presentation, the recent advances in understanding metal-ligand interactions, cation-pi interactions, hydrogen bonding of carbohydrates will be presented. We directly have measured these interactions using a surface forces apparatus (SFA) in aqueous solutions and some insights has been discovered. Some case studies which apply the insights from the measured interactions to translate to the design of advanced materials, especially nano-cellulose/chitin based materials, will be also introduced.