Comparison of the interface between water and four surfaces of native crystalline cellulose by molecular dynamics simulations

Molecular Dynamic (MD) simulations were performed for the four surfaces of native crystalline cellulose. In all cases, only the topmost surface layer of the crystalline cellulose is structurally affected by the water outside the surface. Except for the glucose orientation repeat symmetry, the monoclinic 110 surface and the triclinic 010 surfaces are very similar. Likewise, the monoclinic 1-10 surface is very similar to the triclinic 100 surface. The two latter surfaces are denser and were found to be more hydrophilic than the two former. All surface layer molecules are equivalent in the monoclinic 110 and triclinic 010 surfaces, i.e., the odd/even duplicity breaks down for the monoclinic :110 surface, On the other hand, alternate molecules have different geometric and energetic properties in the monoclinic 1-10 and triclinic 100 surfaces, such that solvation of the triclinic 100 surface induces a translational asymmetry reminiscent of the monoclinic form. The results are discussed with respect to electron microscopy, scanning force microscopy, solid state NMR and protein binding data. (C) 1998 Elsevier Science Ltd. All rights reserved.