Medium dependent dual turn on/turn off fluorescence sensing for Cu²⁺ ions using AMI/SDS assemblies

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Materials Science

Background:

• Amiloride (AMI) is typically a non-fluorophore but can be modified for sensing applications.
• Anionic surfactants like sodium dodecyl sulfate (SDS) form dynamic assemblies (micelles) that can influence molecular behavior.
• Metal ion detection is crucial in environmental monitoring and biological studies.

Purpose of the Study:

• To investigate Amiloride (AMI) as a tunable fluorescent sensor for copper ions (Cu2+).
• To explore the role of sodium dodecyl sulfate (SDS) concentration and pH on AMI's sensing capabilities.
• To elucidate the mechanism behind AMI's fluorescence response in SDS-metal ion systems.

Main Methods:

• Utilized fluorescence spectroscopy to monitor changes in Amiloride's emission.
• Investigated Amiloride-SDS interactions at various concentrations and pH levels.
• Studied the effect of copper ion (Cu2+) addition on the Amiloride-SDS assemblies.

Main Results:

• Amiloride's fluorescence intensity and emission wavelength were significantly altered by SDS concentration and pH.
• SDS micellation was enhanced by increasing copper ion concentrations.
• Tunable 'turn on/turn off' fluorescence responses of Amiloride were observed for Cu2+ detection.
• Electrostatic interactions between metal cations and SDS drive Cu2+ ions to the vicinity of AMI within micelles.

Conclusions:

• Amiloride can be effectively utilized as a tunable fluorescent sensor for Cu2+ ions in SDS solutions.
• The pH and SDS concentration are critical parameters for optimizing Cu2+ sensing with Amiloride.
• The study provides a comprehensive understanding of the fluorescence mechanism for Cu2+ sensing using AMI-SDS assemblies.