Two types of gold nanoparticles, covered with SiO 2 shell and located on the SiO 2 large nanoparticle-carrier, have been synthesized and used as antiviral agents against adenoviruses. Both antiviral effect and virucidal action of the nanoparticles have been studied. It has been shown that both types of nanoparticles demonstrate antiviral action. Dependence of antiviral activity of nanoparticles on their concentration has been studied. Nonmonotonic dependence of the antiviral effect on nanoparticles concentration has been observed and discussed. The antiviral action of complex nanoparticles against adenovirus is important because of low toxicity of the gold nanoparticles covered with SiO 2 shell and of Au-SiO 2 carrier nanoparticles.

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There are many experiments demonstrating antiviral activity of non-functionalised nanoparticles. However, there is no unified view on the interaction between the nanoparticles and viruses, which could explain all the features of this action. The idea of physical reasons of antiviral activities of non-functionalised nanoparticles against various viruses has been proposed previously and applied for explanation of our experimental results. As the features of antiviral action of nanoparticles are similar to some features of near-field interactions, the main reason of antiviral activities is supposed to be the near-field interaction between the virus and the nanoparticle. In the work the proposed mechanism is justified, described, discussed and applied for explanation of existed experimental results on antiviral activity of non-functionalised nanoparticles of different research groups. It is shown that the mechanism allows explaining various experimental results. Consequently, we demonstrate that the near-field interaction between the virus and the nanoparticles may be the main reason for antiviral action of the nanoparticles.

Wide range of applications of nanoparticles causes the need to study their properties, and the influence of the interparticle interaction on the formation of the nanosystem properties is a well-known experimental phenomenon. The aim of this work is to study the influence of interparticle interactions on the properties of nanosystems theoretically. The influence of the interparticle interaction was simulated based on the near-field interaction potential and local field distribution. The local field distribution in the system was calculated using the Green function method and the concept of the effective susceptibility. The results show that interaction between nanoparticles can be neglected if the distance between them is bigger than the critical one. Expressions for evaluation of the efficiency of the interparticle coupling were proposed and compared with the existing experimental results. The results of the simulation are in good agreement with the measured values of the critical interparticle distance. The approach may be useful for simulation of interactions in the system of many nanoparticles and for engineering of nanostructures for different applications.

The antiviral activity of nonfunctionalized gold nanoparticles (AuNPs) against herpes simplex virus type-1 (HSV-1) in vitro was revealed in this study. We found that AuNPs are capable of reducing the cytopathic effect (CPE) of HSV-1 in Vero cells in a dose- and time-dependent manner when used in pretreatment mode. The demonstrated antiviral activity was within the nontoxic concentration range of AuNPs. Interestingly, we noted that nanoparticles with smaller sizes reduced the CPE of HSV-1 more effectively than larger ones. The observed phenomenon can be tentatively explained by the near-field action of nanoparticles at the virus envelope. These results show that AuNPs can be considered as potential candidates for the treatment of HSV-1 infections.