Water Structuring over the Hydrophobic Surface of Cellulose

Abstract

Many important biological solutes possess not only polar and hydrogen-bonding functionalities but also weakly hydrating, or hydrophobic, surfaces. While the aggregation of these hydrophobic surfaces has been shown to play an important role in the aggregation of individual chains of cellulose, it is not known whether the water structuring imposed by these hydrophobic surfaces more closely resembles that associated with small hydrophobic solutes like methane and fats or more closely resembles that associated with extended hydrophobic surfaces like mica or waxy planes. By using molecular dynamics simulations to characterize the water molecule orientations over different regions of the 100 surface of cellulose in contact with water, it was found that the hydrophobic strips of the cellulose crystal are sufficiently narrow that they hydrate like a fatty acid chain, rather than like a more extended surface, suggesting that their aggregation would be dominated by entropy rather than enthalpy.

Revealing the Hydrophobicity of Natural Cellulose by Single-Molecule Experiments

“…Yet, the axial direction of the ring is hydrophobic since the hydrogen atoms of C−H bonds are located on the axial positions of the ring. 9,12,13 Thus, NC is actually an amphiphilic molecule.…”

On the anomalous temperature dependence of cellulose aqueous solubility

“…In relation to this observation, it is interesting to note that cellulose has a strong amphiphilic character, with much of its properties in aqueous environments, including solubility, thus being governed by hydrophobic effects (Bergenstråhle et al 2010;Miyamoto et al 2014;Lindman et al 2010;Medronho et al 2012). It is tempting to assume that similar mechanisms as for purely hydrophobic substances could be important for carbohydrates as well.…”

Paper-based plasticizer-free sodium ion-selective sensor with camera phone as a detector

“…In addition, although cellulose paper is usually considered highly hydrophilic because water readily adsorbs and spreads, its remarkable hydrophobic nature originating from some non-hydrogen bonding, and non-polar protons on cellulose haves also been well recognized. 33,34 This hydrophobic feature is expected to further enhance the residence of the ion sensing components on the filter paper owing to hydrophobic interactions when paper is soaked in water. Indeed, after soaking a paper circle with the 9/32’’ sensing area in 1 mL Tris buffer for 24 h under gentle shaking, the level of KTFPB and CH 1 that leached into the aqueous phase are less than 2%, and the amount of sodium ionophore VI present in the aqueous phase is about 5%.…”