Non-DLVO adhesion of F-specific RNA bacteriophages to abiotic surfaces: Importance of surface roughness, hydrophobic and electrostatic interactions

We report on the adhesion features of three F-specific RNA-phages (MS2, GA and Qβ) onto surfaces (1-dodecanethiol gold-coated surface, glass, polypropylene and stainless steel) that significantly differ with regard to their surface roughness and hydrophobic/hydrophilic balance. The number of adhered phages on the surfaces is quantified using RT-PCR. Adhesion experiments are performed under static conditions in the absence of bulk phages aggregation (1 mM and 100 mM NaNO3 electrolyte, pH 7). The nanoscale surface features and the hydrophobicity of the deposition substrates are quantitatively addressed using Atomic Force Microcopy and Chemical Force Microscopy. The hydrophobicity of the phages is evaluated from their propensity to adhere onto flat and highly hydrophobic surface. Results show that, regardless of electrolyte concentration and surface roughness, the adhesion capacity of phages systematically follows the hydrophobicity sequence MS2 < Qβ < GA. The capacity of each phage to adhere onto the surfaces increases with increase in the degree of hydrophobicity and/or the roughness of the deposition substrate. Increasing the electrostatic interactions between phages and deposition surface by decreasing solution ionic strength leads to a reduction in surface concentration of adhered phages except for cases where the roughness of the deposition surface is significant. Altogether, the results obtained confirm the limited ability of the classical DLVO theory to predict the adhesion of complex viral (nano)particles to surfaces and emphasize the necessity to take into account the roughness of the deposition substrate and the hydrophobicity degree of both viruses and surfaces.