Fe-Doped Red Fluorescent Carbon Dots for Caffeine Analysis in Energy Drinks Using a Paper-Based Sensor

Area of Science:

• Analytical Chemistry
• Materials Science
• Nanotechnology

Background:

• Caffeine detection in energy drinks is crucial for quality control and consumer safety.
• Existing methods can be costly, time-consuming, or require specialized equipment.
• Development of sensitive, selective, and portable detection techniques is needed.

Purpose of the Study:

• To develop a highly sensitive and selective method for caffeine detection in energy drinks.
• To utilize eco-friendly synthesized iron and nitrogen co-doped carbon dots (Fe-NCDs) as fluorescent probes.
• To create a portable, low-cost sensing platform using a microfluidic paper analytical device (µPAD) coupled with smartphone detection.

Main Methods:

• Synthesis of uniform, quasi-spherical Fe-NCDs via an eco-friendly hydrothermal method.
• Fabrication of a µPAD embedding Fe-NCDs for fluorescence-based caffeine sensing.
• Quantification of caffeine using smartphone imaging and ImageJ software analysis of fluorescence enhancement.

Main Results:

• Fe-NCDs exhibited strong red photoluminescence suitable for sensing.
• A linear correlation between fluorescence enhancement and caffeine concentration (1-40 µg/mL) was observed.
• Achieved low limits of detection (0.024-0.032 µg/mL) with high selectivity and validated accuracy in commercial samples.

Conclusions:

• The developed Fe-NCD-based µPAD system offers a sensitive, selective, and cost-effective method for on-site caffeine detection.
• This approach provides an environmentally sustainable solution for energy drink analysis.
• The method holds significant potential for applications in food safety and quality control.