Evidence for Considerable Metal Cation Concentrations from Lithium Intercalation Compounds in the Nano–Bio Interface Gap

An experimental investigation of how electrostatics and ion dissolution impact the interaction between nanosheets of lithium intercalation compounds and supported lipid bilayers has revealed evidence for considerable metal cation concentrations in the nanosheets–bilayer (the “nano–bio interface”) gap. Specifically, elevated concentrations of aqueous metal ions in the 1 mg/L concentration regime produce vibrational sum frequency generation signal intensity changes that are commensurate with the induction of compositional membrane asymmetry. This outcome is consistent with the notion that the induction of bilayer asymmetry by LiCoO 2 nanosheets occurs through a noncontact mechanism that primarily involves the interaction of negatively charged lipids with dissolved ions concentrated within the electrical double layers present in the nano–bio interface gap. Our findings provide a possible avenue for redesign strategies that mitigate noncontact interactions between nanomaterials and biological interfaces, enabling the design of new energy storage materials with reduced environmental impacts.