Twisted Intramolecular Charge Shuttle (TICS) Enables Ultrafast Ratiometric Sensing and Imaging of Nitrite.

Area of Science:

• Analytical Chemistry
• Chemical Sensing
• Molecular Engineering

Background:

• Ratiometric fluorescence sensing provides enhanced reliability but lacks generalizable design mechanisms.
• Developing efficient probes for analytes like nitrite (NO2-) remains a significant challenge.

Purpose of the Study:

• To introduce a novel, mechanism-driven strategy for ultrafast and sensitive nitrite detection.
• To establish the twisted intramolecular charge shuttle (TICS) process as a versatile platform for probe design.

Main Methods:

• Engineered a pyronin fluorophore by incorporating an o-phenylenediamine (OPD) fragment.
• Utilized the TICS process, modulated by nitrite, to generate a ratiometric fluorescence response.
• Developed a portable device for on-site nitrite quantification and imaged endogenous nitrite in plants.

Main Results:

• Achieved a low nitrite detection limit of 6.6 nM with an ultrafast response time of 18 seconds.
• Demonstrated the probe's utility in a portable device for rapid food and water analysis.
• Successfully visualized endogenous nitrite dynamics in living plants under environmental stress.

Conclusions:

• The TICS process offers a powerful, mechanism-driven approach for designing advanced ratiometric fluorescence probes.
• This strategy represents a shift from empirical screening to rational molecular engineering for chemical sensing.
• The developed probe enables rapid, sensitive, and visual detection of nitrite in diverse real-world scenarios.