Nitrogen-doped graphene quantum dots based fluorescent probe for highly sensitive detection of thiosulfate anion and oxidative compounds

Owing to the huge threat to human health and environment from thiosulfate anion (S₂O₃²⁻) widely used in various fields, the development of an effective detection method for S₂O₃²⁻ is urgently desired. Herein, we developed an iodine (I₂) mediated nitrogen-doped graphene quantum dots (I₂-mediated N-GQDs) as a fluorescence “off-on” probe for S₂O₃²⁻ by iodimetry reaction oriented strategy. Firstly, I₂ interacted with N-GQDs to form non-fluorescent N-GQDs/I₂ complex due to the inner filter effect (IFE). In the presence of S₂O₃²⁻, the iodimetry reaction between I₂ and S₂O₃²⁻ disintegrated N-GQDs/I₂ complex and re-switched on the quenched photoluminscence of N-GQDs. The I₂-mediated N-GQDs nanoprobe with a limit of detection down to 93 pM has been successfully used to sense S₂O₃^2- in biological fluids and living cells. Moreover, the I₂-mediated N-GQDs/S₂O₃²⁻ nanoplatform could further detect oxidative compounds such as hydrogen dioxide, dichromate, permanganate, iron ion (III), copper ion (II), and cerium ion (IV).