“Switch-On” Fluorescent Sensing of Ascorbic Acid in Food Samples Based on Carbon Quantum Dots–MnO₂ Probe

Abstract

This work describes a "switch-on" fluorescence approach for sensing of ascorbic acid (AA) in food samples. In the present method, the fluorescence intensity (FL) of carbon quantum dots (CQDs) was first quenched by addition of MnO2 nanosheets through an inner filter effect to form a CQDs-MnO2 probe. When reductive AA was introduced into the quenched CQDs solution, the added MnO2 was destroyed due to the redox reaction between AA and MnO2 nanosheets, and the FL of the system was recovered. Under the optimal conditions, the limit of detection for AA was 42 nM, with a wide concentration linear range of 0.18-90 μM. Furthermore, the as-fabricated fluorescent sensing system was successfully applied to the analysis of AA in fresh fruits, vegetables, and commercial fruit juices samples with satisfactory results.

Microwave-assisted Synthesis of N,S-co-carbon Dots as Switch-on Fluorescent Sensor for Rapid and Sensitive Detection of Ascorbic Acid in Processed Fruit Juice

“…Fresh fruits (kiwi, tomato, citrus reticulata, mango, and apple) samples were prepared according to the procedure described in a previous paper. 19 First, all of the samples were washed with ultrapure water and dried naturally in air at room temperature. These fruits were then accurately weighed and homogenized using a commercial blender.…”

“…17,18 Till now, various QDs fluorescence sensors (e.g. CdTe, 19 Cu-ZnCdS, 20 MnO2, MoS2, and AuNCs) have been developed for highly sensitive and selective detection of AA in real samples. 21,22 However, these QDs exhibited various limitations, including complicated and expensive preparation processes, poor biocompatibility, and negative effect on food and the environment.…”

“…Recently, N,S-co-CDs based fluorescence sensors, including N,S-co-CDs/Fe 3+ and N,S-co-CDs/MnO2 systems, have been applied to the detection of AA via "on-off-on" switchable model. 15,19 In the N,S-co-CDs/Fe 3+ system, the original fluorescence of N,S-co-CDs was firstly quenched by Fe 3+ and then recovered by AA, which exhibited lots of merits, such as higher selectivity, nontoxicity, and high photo-induced electron transfer. However, the preparation method for N,S-co-CDs is extensively focused on the hydrothermal method, which is limited by timeconsuming, rigorous experimental conditions, and difficulty of obtaining CDs powder directly.…”

‘Turn‐on’ fluorescence sensing of hydrogen peroxide in marine food samples using a carbon dots–MnO2 probe

“…[19][20][21][22][23][24] Combining fluorescent probes with other functional nanomaterials is a widely exploited strategy for construction of ideal sensors. [25][26][27][28] MnO 2 nanosheets, which have a large specific surface area and strong light absorption capability with wide wavelength range, are promising fluorescence quenchers that have attracted extensive attention in developing 'turn-off-on' fluorescence sensing systems [27,28] and electrochemical analysis systems. [29] Moreover, MnO 2 nanosheets can be reduced to Mn 2+ , which may benefit the environment and human health.…”

Redox luminescence switch based on Mn2+‐doped NaYF4:Yb,Er upconversion nanorods

“…The luminescence intensity of UCNRs was recovered after addition of AA, GSH or Cys due to MnO 2 was reduced to Mn 2+ , which has no quenching effect on UCNRs. The Cys, GSH and AA play key roles in biological systems . Aberrant levels of Cys, GSH and AA in humans could be caused many diseases, such as liver damage, skin lesion, AIDS, Alzheimer disease, cold, scurvy and caner .…”