Estimation of the Negative Charge of Phi6 Virus and Its Variations with pH Using the Literature XPS Data

Electrostatic charge significantly influences microorganism–surface interactions, including viral adhesion and transmission. While bacterial surface charges are well characterized using electrophoretic mobility and X-ray photoelectron spectroscopy (XPS), similar studies for viruses are limited. This work bridges the gap by estimating the negative surface charge of the Phi6 bacteriophage using XPS data. A novel approach is applied, combining chemical functionalities derived from XPS with a system of equations to quantify surface polysaccharides, proteins, hydrocarbons, and negatively charged groups (RCOO− and R2PO4−). The results indicate a predominance of proteins on the viral surface and a pH-dependent negative charge: phosphate groups dominate at low pH (1–3), while both groups contribute equally at pH 4–9. These findings provide a deeper understanding of virus–surface interactions and underscore the importance of pH in modulating viral surface charge. This method, which surpasses traditional electrophoretic mobility techniques, offers new perspectives for studying viral adhesion and developing improved antiviral materials and disinfection strategies.