Functionalisation of Inorganic Material Surfaces with Staphylococcus Protein A: A Molecular Dynamics Study

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Molecular Biophysics

Background:

• Staphylococcus protein A (SpA) from Staphylococcus aureus binds to antibody Fc regions, enabling antibody extraction.
• SpA's integration with inorganic materials offers potential for novel diagnostics and therapeutics.

Purpose of the Study:

• To investigate Staphylococcus protein A (SpA) adsorption on diverse inorganic surfaces using molecular dynamics simulations.
• To understand the influence of surface charge on SpA orientation and structural integrity.

Main Methods:

• Fully atomistic molecular dynamics simulations were employed.
• Adsorption of SpA was studied on negatively charged silica, positively charged, and neutral surfaces.

Main Results:

• SpA, negatively charged at pH 7, adsorbed on all simulated inorganic surfaces.
• Adsorption on charged surfaces resulted in more specific protein orientation compared to neutral gold surfaces.
• SpA structure remained largely intact across all surfaces.
• Optimal adsorption occurred on negatively charged, siloxide-rich silica, preserving Fc binding site accessibility.

Conclusions:

• Electrostatic interactions predominantly govern SpA adsorption on inorganic surfaces.
• Findings are transferable to various inorganic materials, guiding the design of SpA-based diagnostic and therapeutic applications.
• SpA's selective adsorption properties can be leveraged for antibody conjugation to nanoparticles.