Cluster-mediated assembly of lipid-coated carbon nanotubes for biomimetic water channels

The biomimetic design of artificial water channels, particularly carbon nanotube porins (CNTPs), seeks to replicate the exceptional permeability and selectivity of biological aquaporins for water purification and biomedical applications. However, the fundamental fabrication step-the self-assembly of lipid coatings around carbon nanotubes (CNTs)-remains a molecular-scale "black box," hindering rational design. Here, we employ molecular dynamics simulations to uncover the mechanistic pathway and energetic landscape governing the formation of lipid-coated CNTs. We reveal a universal cluster-mediated assembly mechanism: lipids pre-assemble into clusters in solution before cooperatively coating the CNT. Crucially, we identify two distinct thermodynamic end-states-partially wrapped (PWS) and fully wrapped states-whose stability is tunable by the CNT's dimensions and lipid cluster size. Free-energy calculations demonstrate that increasing CNT length or diameter selectively stabilizes the PWS, driving a thermodynamic transition from co-existence to PWS dominance. These findings provide fundamental insights into the self-assembly kinetics of lipid-CNT systems and offer valuable theoretical guidance for the rational design and tunable fabrication of functional CNTPs.