Study On Portable Strategies For The Detection Of Antioxidant And Al³⁺ Based On Carbon Dots

Due to the simple synthesis,excellent optical properties and low toxicity,carbon dots(CDs)have shown broad application prospects.In this article,blue fluorescent CDs are synthesized using naringin as the precursor,followed with the characterization of basic structures and optical properties.Besides,the portable strategies for determining antioxidant and Al³⁺are developed based on this CDs.The main results are as follows:(1)Blue fluorescent CDs are synthesized with naringin as the precursor.The average size of CDs is 1.17 nm,the surface groups include epoxy groups,hydroxyl groups and carboxyl groups,the quantum yield(QY)is 28.33%,and the fluorescence peak locats at 420nm when excited by 360 nm light.The CDs have excitation-dependent fluorescent property,p H-dependent fluorescence property and anti-photobleaching property.(2)Based on the quenching effect of MnO₂ on blue fluorescent CDs,and the characteristics of MnO₂ catalyzing the oxidation of o-phenylenediamine(OPD)to o-phenylenediamine oxide(OPDox),a portable stragety is developed for the determination of antioxidatnt.Taking glutathione(GSH)as a standard,it's shown that the fluorescence at420 nm of CDs recovers,while the fluorescence at 560 nm of OPDox weakens after introducing GSH into the CDs/MnO₂/OPD system.Therefore,according to the ratio of fluorescence intensity at 420 nm and 560 nm of the detection system,the GSH could be detected through fluorescence spectrometry with the detection limit of 1.89 n M.At the same time,based on the intensity changes in two types fluorescence of CDs and OPDox in this system,portable detection of GSH can be achieved with the help of smartphone,UV lamp and RGB analysis software.The detection limit is 8.33 n M.Finally,this portable strategy can be further applied to the determination of antioxidant properties of food(lemon)and has a significant positive correlation with the traditional DPPH method(Pierce correlation coefficient is 0.9027).(3)Based on the blue fluorescent CDs,a portable detection strategy for Al³⁺is constructed.Al³⁺induces blue fluorescent CDs to agglomerate,which causes the increase of conjugated?system,and further induces the generation of a new fluorescence peak at 500nm of CDs.Using the ratio of fluorescence intensity at 500 nm to 420 nm(I₅₀₀/I₄₂₀)as the detection signal,Al³⁺could be detected by fluorescence spectrometry with the detection limit of 6.15 n M.At the same time,based on the fluorescence color of CDs under UV light changes from blue to green when the Al³⁺concentration gradually increases,Al³⁺could be detected by smartphone and RGB analysis software to identify the change in fluorescence color of CDs,with a detection limit of 6.72 n M.In addition,the higher specificity and spiked recovery(90.46-105.23%)could meet the detection of Al³⁺in real samples.