Rhodamine-based highly sensitive colorimetric off-on fluorescent chemosensor for Hg2+ in aqueous solution and for live cell imaging

Abstract

A novel rhodamine-based highly sensitive and selective colorimetric off-on fluorescent chemosensor for Hg(2+) ions is designed and prepared by using the well-known thiospirolactam rhodamine chromophore and furfural hydrazone as signal-reporting groups. The photophysical characterization and Hg(2+)-binding properties of sensor RS1 in neutral N, N-dimethylformamide (DMF) aqueous solution are also investigated. The signal change of the chemosensor is based on a specific metal ion induced reversible ring-opening mechanism of the rhodamine spirolactam. The response of the chemosensor for Hg(2+) ions is instantaneous and reversible. And it successfully exhibits a remarkably "turn on" response toward Hg(2+) over other metal ions (even those that exist in high concentration). Moreover, this sensor is applied for in vivo imaging in Rat Schwann cells to confirm that RS1 can be used as a fluorescent probe for monitoring Hg(2+) in living cells with satisfying results, which further demonstrates its value of practical applications in environmental and biological systems.

Fluorescent Sensors for Measuring Metal Ions in Living Systems

“…The rhodamine thiospirolactam sensor “Lin Hg-1” was used to monitor Hg 2+ in HeLa cells, 244 and a similar sensor, RS1, was applied to rat Schwann cells. 245 Another type of modified rhodamine spirolactam sensor (Chen Hg-1) incorporates a thiolactone moiety, and this was the first sensor used to visualize Hg 2+ in C. elegans . 35c …”

Visualizing metal ions in cells: An overview of analytical techniques, approaches, and probes

“…Fluorescent tools to detect free Hg 2+ have been developed mostly based on rhodamine and these sensors have been applied in living cells [106–109]. For example, recently a rhodamine based chemosensor RS1, which combined a furaldehyde and a thiospirolactam rhodamine chromophore was used in rat Schwann cells [109].…”

“…Fluorescent tools to detect free Hg 2+ have been developed mostly based on rhodamine and these sensors have been applied in living cells [106–109]. For example, recently a rhodamine based chemosensor RS1, which combined a furaldehyde and a thiospirolactam rhodamine chromophore was used in rat Schwann cells [109]. Lastly, a protein-DNA duplex hybrid platform, similar to the sensor for Pb2+ described above has been used to create a highly selective ratiometric Hg 2+ sensor based on the transcription factor MerR [110].…”

1,3,4-Thiadiazol derivative functionalized-Fe3O4@SiO2 nanocomposites as a fluorescent probe for detection of Hg2+ in water samples

“…The limit of detection (LOD) of the probe was calculated to be 48.7 nM for Hg 2+ detection which satises the U.S. EPA (the U.S. Environmental Protection Agency) limits ($2 ppb) of Hg 2+ detection in drinking water and is a good record compared to some other reports. 38,[46][47][48] The selectivity of the synthesized probe was tested in presence of some interfering ions. Fig.…”