If silver nanoparticles kill bacteria by penetrating the cell membrane, why don't they also kill human cells on contact?
The nanoparticles from your sock will most certainly not reach to your foots cell membrane (Walls are for plants/fungi)  because of the thick layer of dead skin, oils, than about 30 cell thick cornified layer (stratum corneum) build up from practically dead cells (with no nuclei or organelles) but lots of filamentous keratine. This is the most outer shell of your epidermis followed by layers and layers of 4 other tissue types , then comes the &quot;actual&quot; skin dermis and the hypodermis beneath.



If some of the silver-sock -nanoparticles would actually make it through there to basal tissue and reach the cells plasmamembrane, they enter via endocytosis, and start to release Ag+ they break all kinds of things, because Ag+ is cytotoxic it induces ROS, damages you Mitochondira, disturb some pathways... you get the point.

However this was proven to happen within human in vitro celllines.



a few in vivo studies showed that Ag-NPs cause adverse effects on reproduction, malformations, and morphological deformities indifferent non-mammalian animal model.

Says &quot;Review: A systematic review on silver nanoparticles-induced cytotoxicity: Physicochemical properties and perspectives
https://doi.org/10.1016/j.jare.2017.10.008