Real-time monitoring of the dissolution of silver nanoparticles by using a solid-contact Ag⁺-selective electrode

The dissolution kinetics of silver nanoparticles (Ag NPs) to Ag⁺ ions is a critical factor determining the toxicity of silver nanoparticles. In this work, a solid-contact Ag⁺-selective electrode (Ag⁺-ISE) is fabricated and used to monitor the dissolution of Ag NPs. Ordered mesoporous carbon is compared with disordered mesoporous carbon as the solid-contact material for the Ag⁺-ISE. The ordered mesoporous carbon based solid-contact Ag⁺-ISE shows a linear potential response in the range of 1.0 × 10^-6-1.0 × 10^-3 M AgNO₃ with the slope of 55.6 ± 0.8 mV/dec (n = 7) and the detection limit of 10^-6.8 M. The solid-contact Ag⁺-ISE is used to monitor the concentration changes of Ag⁺ during spontaneous dissolution of Ag NPs in deionized water, and the dissolution kinetics of Ag NPs is consistent with that obtained by inductively coupled plasma-mass spectrometry (ICP-MS). Stimulated dissolution of Ag NPs induced by addition of H₂O₂ to the Ag NP solution is also investigated by the proposed solid-contact Ag⁺-ISE. This work provides a fast tool for charactering the dissolution of Ag NPs to Ag⁺ in real time, which is important for studying the toxicology of nanoparticles.