LCI Engineering for Improved Polystyrene Binding: The Impact of Aromatic Amino Acid Substitutions

Polystyrene (PS) is a widely used synthetic polymer with applications in biosensing, medical devices, and packaging. PS often requires surface modifications to enhance biocompatibility, adhesion, and chemical functionality. Material-binding peptides (MBPs) provide a biobased and scalable approach for PS functionalization. Therefore, optimizing their binding properties can ensure stable and efficient binding under industrial application conditions. In this study, we systematically explored how aromatic amino acid substitutions (His, Phe, Trp, and Tyr) affect the PS binding ability of the MBP named liquid chromatography peak I (LCI). A total of 178 aromatic amino acid substitutions were evaluated across all 47 positions of LCI, resulting in the identification of 56 substitutions across 32 positions that improved the PS binding. Among these, the LCI-L4H variant showed the most impoved binding to PS and was further biophysically characterized to determine the surface coverage by surface plasmon resonance (SPR). SPR analysis showed that L4H increased the coating density from 7.90 to 9.18 pmol/cm² (5.52 × 10¹² molecules/cm²), which corresponds to surface coverage of approximately 82%. Molecular dynamics (MD) simulations revealed that the LCI-L4H variant is more compact in size and interacts more frequently through π-π interactions with PS. The high surface coverage and the diversity of the provided functional groups of LCI make the MBP-binding coating a promising alternative to chemical or physical methodologies used in PS functionalization.