The Sensitive Turn-On Fluorescence Detection of Ascorbic Acid Based on Iron(III)-Modulated Nitrogen-Doped Graphene Quantum Dots

Abstract

A rapid, selective and sensitive sensor based on the Fe(III) modulated nitrogen-doped graphene quantum dots (N-GQDs) was developed and applied as fluorescence sensor for ascorbic acid (AA) detection. The N-GQDs was one-step synthesized in an easy and green way using citric acid as the carbon source and urea as nitrogen source. The sensor was based on the different quenching effects of Fe(III) and Fe(II) on the fluorescence intensity of N-GQDs. The fluorescence of N-GQDs was quenched by Fe(III) via the strong selective coordination interaction between them. In the presence of AA, Fe(III) can be transformed to Fe(II) ascribed to the oxidation-reduction reaction, leading to the recovery of fluorescence. On the basis of this principle, a fluorescence sensor for AA detection was constructed. Under optimal conditions, the method showed a response to AA within a concentration range of 1.0-90 μmol L(-1) with a good linear relationship and the detection limit for AA was 18 nmol L(-1). The developed sensor was successfully applied for the determination of AA in beverage samples with quantitative recoveries from 95.3 % to 104.3 %.

Water Soluble Fluorescent Graphene Nanodots

“…Here, LOD has been calculated according to the formula: LOD=3(SD/k) where, SD is the standard deviation of the absorbance intensity at 400 nm in the absence of AA and k is the slope of the calibration curve. Moreover, we also compared the results of AA with previously reported work and detection limits found to be comparable with those reports [Table S2] . So far there is no report of FRET phenomenon of BSA‐GND conjugates used as probe for AA detection.…”

“…Moreover, we also compared the results of AA with previously reported work and detection limits found to be comparable with those reports [ Table S2]. [46][47][48][49][50][51][52][53] So far there is no report of FRET phenomenon of BSA-GND conjugates used as probe for AA detection. Thus, this phenomenon of FRET off of BSA-GND system using AA can be used as a tool for AA detection and estimation.…”

Direct observation of charge transfer between molecular heterojunctions based on inorganic semiconductor clusters

“…S12 and S13 †) failed to detect PL emission signals, which was attributed to the incorporation of Fe 2+ ions acting as good non-radiative recombination centers of electron-hole pairs. 52,53 Given that T3-InS and T4-FeInS clusters in T3-T4-FeInS were conrmed to be independent units by theoretical calculations and UV-vis absorption spectroscopy, the orbital hybridization of Fe 2+ ions with S 2À anions was thought to be conned to the T4-FeInS cluster. Therefore, we inferred that the suppression of possible T3-em PL may be ascribed to the photogenerated charge carrier transfer from T3-InS clusters to T4-FeInS clusters, identical to the dynamic process occurring in T3-T4-MnInS except for the different combination channels, i.e., nonradiative transition within Fe 2+ ions in the former case and radiative transition within Mn 2+ ions in the latter case ( Fig.…”

Supramolecular-Enhanced Charge Transfer within Entangled Polyamide Chains as the Origin of the Universal Blue Fluorescence of Polymer Carbon Dots

“…Fluorescent carbon dots (CDs) are a unique class of spherical nano-meter sized objects contributing to the most recent advances in the fields of sensors, [1][2][3][4][5][6] biosensors, [7][8][9][10] bioimaging, [11][12][13][14] drug delivery, [15][16][17][18] light emitting devices, [19][20] and photocatalysis. [21][22] Apart of their high fluorescent quantum yields, their use in diverse applications is based on their facile fabrication and a broad set of cheap precursor materials, their water solubility, low toxicity and good biocompatibility, as well as their favorable energy and charge transfer properties.…”