photo #5813581

The explanation of the carbon polymers forming when vinegar is added to my tap water. Nanoparticle (NP) clusters with diameters ranging from 20 to 100 nm are reversibly assembled from 5 nm gold (Au) primary particles coated with glutathione (GSH) in aqueous solution as a function of pH in the range of 5.4 to 3.8. As the pH is lowered, the GSH surface ligands become partially zwitterionic and form interparticle hydrogen bonds that drive the self-limited assembly of metastable clusters in <1 min. https://pubs.acs.org/doi/abs/10.1021/acs.langmuir.7b02446