Physicochemically modulated fluorescence-scattering ratiometric sensor for selective and visual detection of levodopa

Area of Science:

• Analytical Chemistry
• Materials Science
• Biomedical Engineering

Background:

• Levodopa (LD) is a crucial drug for Parkinson's disease treatment.
• Accurate and sensitive detection of LD is essential for therapeutic drug monitoring.
• Existing detection methods may lack selectivity, sensitivity, or visual interpretability.

Purpose of the Study:

• To develop a facile fluorescence-scattering ratiometric sensor for visual and selective detection of levodopa (LD).
• To establish a novel physicochemical modulation strategy for LD sensing.
• To enable convenient and efficient assay of LD in real samples.

Main Methods:

• Design of a fluorescence-scattering ratiometric sensor utilizing polyethyleneimine (PEI) and gold nanoclusters (AuNCs).
• Exploitation of the reaction between alkalized LD products and PEI to modulate fluorescence and second-order scattering (SOS) signals.
• Incorporation of Au nanoclusters to enhance SOS signal and provide a stable red background fluorescence.

Main Results:

• The sensor exhibited synchronous changes in fluorescence intensity (at 420 nm) and SOS signal (at 675 nm) with increasing LD concentration.
• A linear relationship was observed between the fluorescence-to-SOS intensity ratio (F/(S/S_blank)) and LD concentration (50.0–30000.0 nM).
• The sensor achieved a limit of detection as low as 50.0 nM, allowing naked-eye identification via fluorescence color change.

Conclusions:

• The developed ratiometric sensor is smart, simple, and efficient for LD detection.
• The physicochemical modulation strategy offers a new and facile approach for selective and visual identification of LD.
• The sensor has been successfully applied to the convenient assay of LD in real samples.