Similarities and Differences Between Cyclodextrin−Sodium Dodecyl Sulfate Host−Guest Complexes of Different Stoichiometries: Molecular Dynamics Simulations at Several Temperatures

Abstract

An extensive dynamic and structural characterization of the supramolecular complexes that can be formed by mixing α-, β-, and γ-cyclodextrin (CD) with sodium dodecyl sulfate (SDS) in water at 283, 298, and 323 K was performed by means of computational molecular dynamics simulations. For each CD at the three temperatures, seven different initial conformations were used, generating a total of 63 trajectories. The observed stoichiometries, intermolecular distances, and relative orientation of the individual molecules in the complexes, as well as the most important interactions which contribute to their stability and the role of the solvent water molecules were studied in detail, revealing clear differences and similarities between the three CDs. Earlier reported findings in the inclusion complexes field are also discussed in the context of the present results. For any of the three native cyclodextrins, the CD(2)SDS(1) species in the head-to-head conformation appears to be a promising building block for nanotubular aggregates both in the bulk and at the solution/air interface, as earlier suggested for the case of α-CD. Moreover, the observed noninclusion arrangements involving β-CD are proposed as the seed for the premicellar (β-CD)-induced aggregation of SDS described in the literature.

Stereochemical features of the physisorption of linear molecules in β-cyclodextrin

“…The type of molecules that can be introduced in the cavity to form an inclusion complex, depends mainly on geometric factors rather than on chemical properties, however these are evidently not the only factors, it is shown that the ability of CDs to form supramolecular assemblies is also due to the effect of conformational adaptation of the host and the guest molecules. In some cases the CD hardly modifies his atomic positions by the inclusion complex formation [3,4], but there are some compounds capable of changing the truncated cone shaped structure of CDs to nanocylinder-like blocks [5,6]. The present work considers the CD cavity like a conical geometry, to take into account these structural changes it could be applied the characteristics of a continuum model for the interaction energy of a cylindrical structure for CDs studied in previous work [7].…”

Molecular Dynamics Study of the Factors Influencing the β-Cyclodextrin Inclusion Complex Formation of the Isomers of Linear Molecules

“…The interaction energy between -CD and a linear molecule is represented by the van der Waals contribution, modelled by a Lennard-Jones (6,12) potential. It depends on two parameters ( , ), where is the depth of the well and is the position where the repulsive branch crosses zero [22][23][24].…”

“…A well-known experimental finding is the existence of an appropriate size of the guest to reach maximum binding affinity in each CD [4][5][6][7], but there is no theoretical justification for this result and the factors influencing this affinity are not known. CDs and their inclusion complexes have been theoretically studied using different computational methods: molecular mechanics (MM) [8,9], molecular dynamics (MD) [6,10], and Monte Carlo simulations (MC) [11,12], where all the atoms of both CDs and guest molecules have been described.…”

Supramolecular Proteoglycan Aggregate Mimics: Cyclodextrin‐Assisted Biodegradable Polymer Assemblies for Electrostatic‐Driven Drug Delivery

“…[9] Some of the 1:2 and 2:1 mol/mol host-guest Abstract: Self-assembled, noncovalent polymeric biodegradable materials mimicking proteoglycan aggregates were synthesized from inclusion complexes of cationic surfactants with g-cyclodextrin and the natural anionic polymer hyaluronan. The amorphous structure of this ternary system was proven by X-ray diffraction and thermal analysis.…”