Fluorescence Sensing Techniques for Ascorbic Acid Detection

Fluorescence sensing has emerged as a versatile and sensitive approach for quantifying ascorbic acid in food, biological fluids and environmental samples. By exploiting the unique photophysical properties of nanomaterials and coordination complexes, researchers have developed “turn-on” and “turn-off” probes in which the emission intensity responds selectively to ascorbic acid via redox reactions, competitive binding or energy-transfer mechanisms. Common platforms include carbon-based quantum dots, metal-ion chelates and semiconductor nanocrystals. Surface functionalisation and heteroatom doping (for example with nitrogen, fluorine or sulphur) tune optical response and improve water solubility, while careful choice of quenching agents such as metal ions or conjugated polymers ensures low detection limits and high selectivity. These advances enable rapid, low-cost assays for pharmaceutical quality control, food processing and real-time monitoring of antioxidant levels in living cells.

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Researchers have synthesised water-soluble carbon dots via a hydrothermal route using citric acid and ethylenediamine, then formed a Fe³⁺–carbon dot complex that is quenched until ascorbic acid reduces Fe³⁺, restoring fluorescence. This platform achieved detection limits in the low micromolar range and demonstrated accurate ascorbic acid measurement in fruit extracts. A second study introduced green, one-pot microwave synthesis of nitrogen/fluorine co-doped carbon dots that exhibit stable single-colour emission. These probes switch off upon Fe³⁺ addition and switch on upon ascorbic acid introduction, with detection limits around one micromolar and elucidation of quenching via inner filter effect and static mechanisms. Finally, a fluorescence resonance energy transfer sensor based on CdS quantum dots and polydopamine offered an “off-on” response: ascorbic acid inhibited polydopamine formation and prevented energy transfer, yielding linear fluorescence recovery across physiologically relevant concentrations and minimal interference from common biomolecules.

Fluorescence Sensing Techniques for Ascorbic Acid Detection publication trend

The graph below shows the total number of articles in fluorescence sensing techniques for ascorbic acid detection across all publications each year (not limited to Nature Index journals).

Technical terms

Fluorescence quenching: A process by which a fluorophore’s emission is reduced through interactions such as energy transfer, collisional deactivation or ground-state complex formation.

Quantum yield: The ratio of emitted photons to absorbed photons, indicating the efficiency of fluorescence emission from a given probe.

Carbon dots: Nanoscale, carbon-based particles with tunable fluorescence, high water solubility and easy surface modification for sensing applications.

Fluorescence resonance energy transfer (FRET): A non-radiative energy transfer mechanism between a donor fluorophore and an acceptor molecule when in close proximity, used to report molecular interactions.

Inner filter effect: Attenuation of excitation or emission light by an absorbing species in solution, often contributing to apparent fluorescence quenching.

References

1. Synthesis of Fluorescent Carbon Dots and Their Application in Ascorbic Acid Detection. Molecules (2021).
2. One-Step Synthesis of Nitrogen/Fluorine Co-Doped Carbon Dots for Use in Ferric Ions and Ascorbic Acid Detection. Nanomaterials (2022).
3. Ascorbic Acid Sensor Based on CdS QDs@PDA Fluorescence Resonance Energy Transfer. Molecules (2022).