Molecular dynamics insights into the selective adsorption of biogenic amines by a crosslinked β-cyclodextrin-citric...

Crosslinked cyclodextrin (CD)-based polymers, particularly those formed with citric acid (CA), have demonstrated promising potential for the adsorption of polar trace contaminants due to their environmentally benign nature and tunable physicochemical properties. In this study, we developed a molecular model of a crosslinked β-cyclodextrin-citric acid polymer (p-β-CD-CA). We investigated its structural features and adsorption behavior towards three biogenic amines (BAs): histamine (HIS), tryptamine (TRP), and putrescine (PUT), using atomistic molecular dynamics (MD) simulations. The polymer model was validated based on simulated molecular weight, density (1.47 g/cm³), and glass transition temperature (T_g≈74 °C), showing strong agreement with experimental data. Adsorption studies were conducted under both aqueous and vacuum conditions to assess dynamic behavior, interaction energies, and hydrogen bonding characteristics. HIS exhibited the strongest binding affinity, followed by TRP and PUT, with interaction energies significantly more favorable in vacuum environments. Detailed analyses of solvent-accessible surface area (SASA), root mean square deviation (RMSD), hydrogen bonding, and radial distribution functions (RDFs) highlighted the central role of water-mediated hydrogen bonding. These findings emphasize the selectivity of p-β-CD-CA for BAs and its potential application in targeted environmental and biomedical adsorption strategies.