An ascorbic acid sensor based on cadmium sulphide quantum dots.

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Biochemistry

Background:

• Vitamin C (ascorbic acid) is a vital nutrient with various health benefits.
• Accurate quantification of ascorbic acid is crucial for dietary monitoring and quality control.
• Existing detection methods may lack sensitivity or require complex sample preparation.

Purpose of the Study:

• To develop a novel Förster resonance energy transfer (FRET)-based fluorescence sensor for sensitive vitamin C detection.
• To utilize cadmium sulphide quantum dots (CdS QDs) and diphenylcarbazide (DPC) for ascorbic acid sensing.
• To validate the sensor's performance with real-world samples.

Main Methods:

• Formation of a QD-DPCD complex where DPC is oxidized to DPCD in the presence of CdS QDs.
• Utilizing FRET from CdS QDs to DPCD, leading to fluorescence quenching.
• Monitoring fluorescence recovery upon addition of ascorbic acid, which reduces DPCD back to DPC.
• Employing fluorescence lifetime analysis to confirm FRET mechanism.

Main Results:

• Demonstrated a FRET-based fluorescence quenching and recovery mechanism for ascorbic acid detection.
• Achieved a dynamic range of 60-300 nM and a low detection limit of 2 nM for ascorbic acid.
• Confirmed the FRET mechanism through fluorescence lifetime studies.
• Successfully applied the sensor to quantify ascorbic acid in orange juice and vitamin C tablets.

Conclusions:

• The developed FRET-based sensor provides a sensitive and accurate method for vitamin C detection.
• CdS QDs and DPC offer a promising platform for developing novel fluorescence-based analytical tools.
• The sensor's applicability to real samples highlights its potential for practical use in food analysis and health monitoring.