Ionophore-Based SERS Sensing for Electrolyte Cations

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Nanotechnology

Background:

• Selective detection of electrolyte cations is crucial for various applications.
• Existing methods often face challenges with sensitivity, selectivity, or matrix interference.
• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity but requires tailored platforms for specific analytes.

Purpose of the Study:

• To develop a SERS-based platform for selective detection of electrolyte cations.
• To investigate the mechanism of signal enhancement through molecular reorientation.
• To demonstrate the platform's efficacy in complex biological samples.

Main Methods:

• Utilizing silver nanoparticles functionalized with chromoionophore I (CHI).
• Exploiting cation-induced reorientation of CHI on the SERS substrate.
• Employing Nuclear Magnetic Resonance (NMR) spectroscopy to confirm conformational changes.
• Applying SERS to detect Ca2+ and Na+ in various matrices, including human serum.

Main Results:

• Demonstrated cation-induced reorientation of CHI molecules from endwise to edgewise configuration.
• Observed enhanced SERS signals due to improved dipole-field coupling.
• Achieved detection limits of 0.1 μM for Ca2+ and 1 μM for Na+ with high selectivity.
• Successfully quantified Ca2+ in undiluted human serum, overcoming matrix interference.

Conclusions:

• The developed SERS platform offers a sensitive and selective method for electrolyte cation detection.
• Molecular reorientation of CHI is a key mechanism for signal transduction and enhancement.
• This approach shows significant potential for advancing ion detection capabilities in complex biological and environmental samples.