Estimation of Nanoparticle’s Surface Electrostatic Potential in Solution Using Acid–Base Molecular Probes. III. Experimental Hydrophobicity/Hydrophilicity and Charge Distribution of MS2 Virus Surface

Abstract

MS2 bacteriophage is often used as a model for evaluating pathogenic viruses’ behavior in aqueous solution. However, the questions of the virus surface’s hydrophilic/hydrophobic balance, the charge distribution, and the binding mechanism are open. Using the dynamic light scattering method and laser Doppler electrophoresis, the hydrodynamic diameter and the ζ-potential of the virus particles were measured at their concentration of 5 × 1011 particles per mL and ionic strength 0.03 M. The values were found to be 30 nm and −29 or −34 mV (by Smoluchowski or Ohshima approximations), respectively. The MS2 bacteriophage surface was also investigated using a series of acid–base indicator dyes of various charge type, size, and structure. Their spectral and acid–base properties (pK a ) are very sensitive to the microenvironment in aqueous solution, including containing nanoparticles. The electrostatic potential of the surface Ψ was estimated using the common formula: Ψ = 59 × (pK a i – pK a ) in mV at 25 °C. The Ψ values were −50 and +10 mV, respectively, which indicate the “mosaic” way of the charge distribution on the surface. These data are in good agreement with the obtained ζ-potential values and provide even more information about the virus surface. It was found that the surface of the MS2 virus is hydrophilic in solution in contrast to the commonly accepted hypothesis of the hydrophobicity of virus particles. No hydrophobic interactions between various molecular probes and the capsid were observed.

Estimation of Nanoparticle’s Surface Electrostatic Potential in Solution Using Acid–Base Molecular Probes I: In Silico Implementation for Surfactant Micelles

“…It should be noted that the described method is used not only for the investigation of micellar-like systems, such as calixarene aggregates, cucurbiturils, polyelectrolytes, and phospholipid bilayers, , but for a variety of different systems as well, such as detonated nanodiamond particles, fullerenols, metal surfaces, and air bubbles . Proteins were also examined with this method, up to a complete bacteriophage virus capsid …”

“…50 Proteins were also examined with this method, 51 up to a complete bacteriophage virus capsid. 52 Interestingly, the same factors accounted for in eq 2 cause the so-called "protein error", hindering pH determination with indicators. 53,54 2.5.…”

Complete Virion Simulated: All-Atom Model of an MS2 Bacteriophage with Native Genome

“…The final charge of the complete virion in our conditions was found to fluctuate around −153|e|, indicating negative surface potential and ζpotential, in accordance with the available experimental information. 29 More detailed information is provided by the RDFs of the ions with respect to the capsid center (see Figure 9b). Within the capsid (at r < 10 nm), the RDFs of the cations have numerous local minima and maxima despite long time and ensemble averaging.…”

Biomolecular Electrostatic Phenomena: An Evergreen Field

“…15 Finally, dynamic light scattering methods and laser Doppler electrophoresis were used to analyze the hydrophilic/phobic character of the MS2 bacteriophage virus. 16 Approximately one-third of the contributions to this virtual special issue concerned methodological aspects, considered from many different points of view. Improvements to continuum models were discussed regarding a better prediction of water molecule distribution around negatively charged solutes, 17 and introducing better analytical estimates of the interaction energy of dielectric particles in a solvent obeying the linearized Poisson−Boltzmann equation.…”

“…Interestingly, a combination of experimental and simulation techniques was used to investigate how the solute electronic structure can condition the reaction field generated by the surrounding solvent . Finally, dynamic light scattering methods and laser Doppler electrophoresis were used to analyze the hydrophilic/phobic character of the MS2 bacteriophage virus …”