Deposition and Aggregation Kinetics of Rotavirus in Divalent Cation Solutions

Aggregation kinetics of rotavirus in aqueous solutions and its deposition kinetics on silica surface in the presence of divalent (Ca2+, Mg2+) cations were studied using complementary techniques of time-resolved dynamic light scattering (TR-DLS) and quartz crystal microbalance (QCM). Within a reasonable temporal window of 4 h, aggregation could be observed at levels as low as 10 mM of Ca2+ and 20 mM of Mg2+. Attachment efficiencies were always greater in Ca2+ solutions of the same concentration, and the critical coagulation concentration (CCC) for rotavirus in Ca2+ solutions was slightly smaller than that in Mg2+ solutions. No aggregation was detected in Na+ solution within the temporal window of 4 h. Deposition experiments showed higher attachment coefficients in solutions containing Ca2+ compared to those obtained in Mg2+ solution. The classic Derjaguin−Landau−Verwey−Overbeek (DLVO) theory failed to predict both the aggregation behavior of rotavirus and its deposition on silica surface. Besides electrostatic interactions, steric repulsions and specific interactions with divalent cations were important mechanisms in controlling rotavirus deposition and aggregation. Experimental results presented here suggest that rotavirus is not expected to aggregate in groundwater with typical hardness (up to 6 mM Ca2+) and rotavirus deposition on silica soil would be more favorable in the presence of Ca2+ than Mg2+.