Electrochemical detection of glutathione by using thymine-rich DNA-gated switch functionalized mesoporous silica nanoparticles.

A novel electrochemical sensor for highly sensitive and selective detection of glutathione (GSH) was developed coupled thymine-Hg-thymine (T-Hg-T) coordination with mesoporous silica nanoparticles (MSN). Hg ions could specifically interact with thymine bases to form strong and stable T-Hg-T complexes. And the electroactive molecules-methylene blue (MB) was sealed in the inner pores of MSN with a unique sequential thymine (T)-rich DNA in the presence of Hg. After the target was added, the formed duplex DNA T-Hg-T complex could deform into single-stranded DNA by a competitive displacement reaction, leading to the release of MB entrapped in the MSN. Thus the target-dependent amount of released MB could be conveniently monitored with an n-dodecanethiol modified screen-printed gold electrode. Using GSH as a model target, the proposed assay showed a wide detection ranging from 1.0nM to 1.0μM with a detection limit of 0.6nM. This strategy was simple and universal for various analytes with different competitive displacement ligands, possessing a great potential for convenient biotools testing and commercial application.