On the Mechanism of Interactions Between Tetracycline and New Chitosan‐Based Materials: Experimental Development Guided by Computational Methods

ABSTRACT In this paper, we employ computational methods to guide the development of new chitosan‐based materials for adsorbing tetracycline in its zwitterionic form (zTC). As tentative materials, we consider three polymers: chitosan (CTS) and chitosan functionalized with either 1‐naphthaldehyde (RCN) or 2‐hydroxy‐1‐naphthaldehyde (RCN1). Electronic structure calculations and molecular dynamics simulations are applied to investigate the adsorption of tetracycline on monomers of CTS, RCN, and RCN1 and, thus, provide molecular‐level insight about the relevant interactions. The computational results indicate that the adsorption mechanism of tetracycline on both RCN and RCN1 monomers is mainly controlled by van der Waals and π – π interactions, while the directional character of H‐bonding does not favor the adsorption on CTS at all. In turn, electronic structure calculations show that the density of low‐energy configurations is greater for zTC–RCN1 than for zTC–RCN, which is likely to favor the adsorption of tetracycline on RCN1. In addition, molecular dynamics simulations confirm that the stability of the complexes follows the order zTC–RCN1 > zTC–RCN > zTC–CTS. To assess the real efficiency of these materials to adsorb tetracycline, we synthesize RCN and RCN1 polymers which are then used in the adsorption experiments. These reveal that the promising RCN1 polymer is actually the most effective one for removing tetracycline from water.