Environment-sensing merocyanine dyes for live cell imaging applications

Area of Science:

• Biochemistry and Molecular Biology
• Cell Biology
• Chemical Biology

Background:

• Environmentally sensitive fluorescent dyes are crucial for visualizing and quantifying protein activation in living cells.
• Merocyanine dyes offer superior brightness, long excitation/emission wavelengths, and detectable fluorescence changes, making them ideal for live cell imaging.

Purpose of the Study:

• To systematically investigate how structural modifications affect the photophysical properties of merocyanine dyes.
• To develop novel fluorescent biosensors for detecting endogenous protein activation, specifically Cdc42, in living cells.

Main Methods:

• Synthesis of a library of 25 merocyanine dyes by combining 5 donor and 5 acceptor heterocycles.
• Optimization of four promising dyes for imaging applications, including adding reactive side chains and improving aqueous solubility via a one-pot method.
• Development of a biosensor for Cdc42 activation using the optimized dyes.

Main Results:

• The study identified four merocyanine dyes with optimal properties for specific imaging tasks.
• Dye mero60 demonstrated a remarkable 1470% increase in fluorescence intensity upon binding activated Cdc42 in vitro.
• The developed dye-based biosensors successfully reported the activation of endogenous Cdc42 within living cells.

Conclusions:

• Structural modifications can fine-tune merocyanine dye properties for enhanced biosensing applications.
• The novel merocyanine dye-based biosensors are effective tools for real-time monitoring of protein activation in cellular environments.
• These biosensors provide a valuable method for studying cellular signaling pathways, such as Cdc42 activation, in live cells.