Unveiling the physical chemistry of silica binding peptide adsorption

Silica-binding peptides (SBPs) are versatile tools for functionalizing silica surfaces in biotechnology, yet the mechanisms underlying their adsorption remain poorly understood. Here, we develop a predictive molecular theory that integrates peptide structure, electrostatic and short-range interactions, and charge regulation effects to model SBP adsorption onto silica. This coarse-grained approach effectively captures the dependence of adsorption on pH, salt concentration, and peptide concentration. We highlight the critical role of residue composition and sequence order in determining binding affinity. Our results reveal that local environmental changes near the surface modulate peptide charge, thus modulating adsorption. For example, at low peptide concentrations and high ionic strength, peptides adopt preferred orientations at the surface. This framework offers new physicochemical insights into peptide-surface interactions and provides a powerful tool for the rational design of SBPs with tailored surface affinity for applications in biosensing, protein immobilization, and nanobiotechnology.