A sensitive fluorescence nanoplatform for monitoring benzoyl peroxide in food using carbon dots coupled with glutathione capped gold nanoparticles as FRET probe.

Herein, a sensitive fluorescence nanoplatform for benzoyl peroxide (BPO) detection is constructed from carbon dots (CDs) and glutathione capped gold nanoparticles (GSH-AuNPs). The fluorescence of CDs is first quenched due to the fluorescence resonance energy transfer (FRET) effect in the presence of GSH-AuNPs, and then effectively recovered when adding BPO. The detection mechanism lies in the aggregation of AuNPs in a high salt background due to oxidation of GSH caused by BPO, thus the amount of BPO is reflected by the variations of the recovered signals. The linear range and detection limit in this detection system is found to be 0.05-200 µM (R2 = 0.994) and 0.1 µg g-1 (3σ/K), respectively. Several possible interferents with high concentration show little influence on BPO detection. The proposed assay exhibits good performance for BPO determination in wheat flour and noodles, demonstrating its applicability for facile monitoring BPO additive amount in real foods.

Lanthanum ions assisted non-enzymatic ratiometric fluorescence probe for monitoring fenthion residues in agro-product samples.

In this work, a La3+ assisted glutathione-capped gold nanoclusters and carbon dots (GSH-Au NCs/CDs) nanoplatform for sensitive detection of fenthion (FEN) is fabricated. The fluorescence response of GSH-Au NCs significantly increases due to aggregation-induced emission enhancement (AIEE) effect induced by La3+, which is further enhanced with adding FEN due to the coordination between La3+ and FEN. Taking the fluorescence intensity of CDs as the signal background, the ratiometric fluorescence of GSH-Au NCs and CDs has a good linear relationship with the FEN concentration from 0.01 to 1.10 µg mL-1, and detecting FEN exhibits a good sensitivity at a low detection limit of 6.74 ng g-1. The La3+ assisted GSH-Au NCs/CDs nanoplatform demonstrates desirable selectivity and applicability for monitoring trace level of FEN in fruit and vegetable samples. The non-enzymatic strategy by taking advantage of successive AIEE of GSH-Au NCs has a great potential for facile screening organophosphate pesticides in agro-products.

Silver ions involved fluorescence "on-off" responses of gold nanoclusters system for determination of carbendazim residues in fruit samples.

Herein, a fluorescence "on-off" system was developed for monitoring carbendazim (CBZ) residues in fruit samples, based on glutathione-gold nanoclusters (GSH-Au NCs) and silver ions (Ag+). First, the fluorescence intensity of GSH-Au NCs was greatly enhanced (turn on) with aggregation-induced emission enhancement (AIEE) effect in the presence of Ag+, then fluorescence quenching occurred (turn off) with adding CBZ by the chelation between CBZ and Ag+. The quenching degree was well linearly dependent on CBZ concentration covering from 0.5 to 20 µM. Moreover, the GSH-Au NCs-Ag+ system exhibited superior selectivity towards CBZ and was sensitive for the determination of CBZ in apple and orange juices with a low detection limit of 0.12 µM. The recoveries of CBZ spiked in fruit samples ranged from 81.0 % to 111.4% with the relative standard deviations less than 6.6%, demonstrating its great potential for monitoring CBZ residues in fruit samples.