pH dependent reversible aggregation of Chitosan and glycol-Chitosan stabilized silver nanoparticles

► The pH dependent aggregation behaviour of Chitosan and glycol-Chitosan stabilized silver nanoparticles was investigated. ► The intensity of hyper-Rayleigh scattering (HRS) was found to increase till pH 9.0 ± 2.0 but dropped dramatically after that. ► The increase and decrease of HRS is attributed to the formation of noncentrosymmetric and centrosymmetric aggregates. ► The pH dependent aggregation behaviour was shown to be reversible over at least 10 pH cycles.