The emergence of antibiotic and anti-inflammatory agents in aquatic and terrestrial systems is becoming a serious threat to human and animal health worldwide. Because pharmaceutical compounds rarely exist individually in nature, interactions between various compounds can have unforeseen effects on their fate. This work demonstrates this important possibility for the case of two typical antibiotic and anti-inflammatory agents (nalidixic acid (NA) and niflumic acid (NFA)) bound at surfaces of eight different soil- and sediment-building minerals. Our multidisciplinary study, which makes use of column transport experiments, vibration spectroscopy and periodic density functional theory calculations, reveals an important increase in NFA binding caused by unforeseen intermolecular interactions with mineral-bound NA. This enhancement is ascribed to the formation of a NFA-NA dimer whose energetically favored formation (-0.5 eV compared to free molecules) is predominantly driven by van der Waals interactions. This novel form of binding opens new possibilities for accurately predicting the fate of co-existing antibiotics and anti-inflammatory agents in nature.<br/>

Drug co-binding at mineral surfaces

253rd National Meeting (2017)

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