An irreversible paper-based profluorescent nitroxide probe for the selective detection of ascorbic acid

Area of Science:

• Analytical Chemistry
• Biochemistry
• Materials Science

Background:

• Ascorbic acid (vitamin C) is a vital antioxidant with numerous biological functions.
• Accurate detection of ascorbic acid is crucial for biological and nutritional studies.
• Existing detection methods may lack specificity or sensitivity for ascorbic acid.

Purpose of the Study:

• To develop a novel profluorescent nitroxide probe (ProN6) for selective ascorbic acid detection.
• To investigate the mechanism of ascorbic acid detection using the ProN6 probe.
• To evaluate the probe's performance in quantitative analysis of ascorbic acid.

Main Methods:

• Synthesis of a profluorescent nitroxide probe, ProN6.
• Detection of ascorbic acid via a switch-on fluorescence method.
• Kinetic fluorescence studies and Density Functional Theory (DFT) calculations.
• Application of the probe as a paper-based fluorescent sensor.

Main Results:

• ProN6 selectively detected ascorbic acid over other reductants via a cascade reductive lactonization.
• The probe exhibited a switch-on fluorescence mechanism, preventing reoxidation and ensuring high detection precision.
• ProN6 demonstrated higher reactivity and a lower Gibbs free energy for ascorbic acid-induced cyclization compared to ProN5 and ProN7.
• Sensitive detection limits were achieved: 77.9 nM in solution and 195.9 μM on paper.
• Accurate quantitative analysis of ascorbic acid in commercial supplements was demonstrated using the paper-based sensor.

Conclusions:

• The synthesized ProN6 probe offers a sensitive and specific method for detecting ascorbic acid.
• The probe's unique mechanism and paper-based application provide a practical tool for vitamin C analysis.
• This work contributes to the development of advanced fluorescent probes for biochemical analysis.