A smartphone-integrated ratiometric fluorescent sensor for ascorbic acid determination using microplasma-enabled...

Area of Science:

• Analytical Chemistry
• Materials Science
• Biochemistry

Background:

• Ascorbic acid (AA) is a vital nutrient, and its accurate quantification in food matrices like fruits is crucial for quality control and nutritional assessment.
• Existing methods for AA detection can be complex, time-consuming, or require specialized laboratory equipment, limiting their application in field settings.
• Developing a rapid, sensitive, and user-friendly sensing platform for AA determination remains an important goal in food analysis.

Purpose of the Study:

• To develop a switchable ratiometric fluorescent sensing platform for the visual and quantitative determination of ascorbic acid (AA) in fruits.
• To integrate nitrogen-doped carbon dots (N-CDs) and Rhodamine B into a smartphone-assisted sensing system for enhanced accessibility and usability.
• To evaluate the performance of the developed platform in terms of sensitivity, selectivity, and applicability to real fruit samples.

Main Methods:

• Synthesis of blue-emission nitrogen-doped carbon dots (N-CDs) using liquid dielectric barrier discharge microplasma, with characterization of their size and quantum yield.
• Fabrication of a ratiometric fluorescent sensing platform utilizing the fluorescence quenching of N-CDs by Hg²⁺ and subsequent recovery by AA (turn-off/turn-on mechanism).
• Development of a smartphone-assisted detection method by converting fluorescence color changes to RGB values for visual and quantitative analysis of AA, alongside traditional fluorescence spectrometry.

Main Results:

• The synthesized N-CDs exhibited an average size of 3.65 nm and a quantum yield of 18% at 345 nm excitation.
• The sensing platform demonstrated good linearity for AA detection in the ranges of 3-170 μM (spectrometer) and 5-170 μM (smartphone).
• Achieved low detection limits of 0.98 μM (spectrometer) and 2.90 μM (smartphone), with satisfactory recovery rates in real fruit samples.

Conclusions:

• The fabricated switchable ratiometric fluorescent platform based on N-CDs and Rhodamine B enables sensitive and visual determination of ascorbic acid (AA).
• The smartphone-assisted sensing capability significantly enhances the practicality and accessibility of AA analysis, particularly for on-site fruit quality assessment.
• This innovative platform holds promise for widespread application in food safety and nutritional monitoring.