El-Maghrabey Mahmoud, Yamamichi Aya, Abdel-Hakim Ali, Kishikawa Naoya, Kuroda Naotaka
Department of Analytical Chemistry for Pharmaceuticals, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt.
Antioxidants (Basel). 2025 Aug 22;14(9):1034. doi: 10.3390/antiox14091034.
Antioxidants have drawn much interest owing to their capacity to shield the human body from reactive oxygen species (ROS). Therefore, it is essential to develop a quick and easy assay for the evaluation of antioxidants and for imaging their distribution in food. Herein, we describe a fluorescence measurement platform for assessing and visualizing antioxidant capacity. Our method is based on using the composite of graphene quantum dots (GQDs) with Fe (Fe-GQDs) as a reagent for evaluating and imaging the antioxidant capacity in foods using a fluorescence turn-off-on strategy. The fluorescence of GQDs was found to be selectively quenched with Fe at pH 3.5. Upon addition of an antioxidant, Fe is reduced to Fe, and the fluorescence of GQDs is regained. Next, we investigated the fluorescence intensity after the reaction of Fe-GQDs with seven typical antioxidants, and it showed excellent sensitivity down to 0.60 µM of antioxidant. Next, using Fe-GQDs as a reagent, we developed a paper-based fluorescence imaging method for antioxidants in foods. Furthermore, we analyzed the distribution of antioxidant capacity on cucumber and carrot slices (tips, central parts, and shoulders). Next, the antioxidant capacity of cucumber and carrot slice extracts was measured, and the results were consistent with the fluorescence imaging results of the intact slices.
抗氧化剂因其能够保护人体免受活性氧（ROS）的侵害而备受关注。因此，开发一种快速简便的方法来评估抗氧化剂并成像其在食物中的分布至关重要。在此，我们描述了一种用于评估和可视化抗氧化能力的荧光测量平台。我们的方法基于使用石墨烯量子点（GQDs）与铁的复合物（Fe-GQDs）作为试剂，采用荧光开关策略来评估和成像食物中的抗氧化能力。发现在pH 3.5时，GQDs的荧光会被铁选择性猝灭。加入抗氧化剂后，铁被还原为亚铁，GQDs的荧光得以恢复。接下来，我们研究了Fe-GQDs与七种典型抗氧化剂反应后的荧光强度，结果表明其对低至0.60 μM的抗氧化剂具有出色的灵敏度。接下来，以Fe-GQDs为试剂，我们开发了一种用于食物中抗氧化剂的纸质荧光成像方法。此外，我们分析了黄瓜和胡萝卜切片（尖端、中部和肩部）上抗氧化能力的分布。接下来，测量了黄瓜和胡萝卜切片提取物的抗氧化能力，结果与完整切片的荧光成像结果一致。
