Construction Of Ferric Ion Sensing System Based On Nitrogen-doped Carbon Dots And Quality Evaluation Of Chinese Yam With Different Foliar Fertilizer Treatments

ObjectiveThe fluorescence sensing system based on nitrogen-doped carbon dots is constructed to realize the rapid and sensitive measurement of ferric ion,so as to replace the existing conventional methods.The content changes of components in Chinese yam treated with different foliar fertilizer were studied in order to evaluate its quality and provide guidance for clinical application and consumption of Chinese yam.MethodsThe fluorescent carbon dots were synthesized by microwave carbonization method,and the synthesis parameters such as the molar ratio of citric acid and urea,the material-to-liquid ratio of precursor and water,microwave reaction time,microwave firepower,and purification solvent were optimized.The optimized synthesis product is subjected to spectral characterization,morphology characterization,and structure characterization to determine the synthesized product.A ferric ion sensing system based on carbon dots was established,for the determination of the content of yam,and the quenching mechanism of nitrogen-doped carbon dots by ferric ion was studied.The Chinese yam samples treated with different foliar fertilizers were obtained through field experiments,and the contents of seven components in them were determined by conventional analysis methods.The weight of fresh individual Chinese yam was obtained for yield information,and the contents of water,polysaccharides and protein were measured by drying method,phenol-sulfuric acid colorimetry and Kjeldahl nitrogen determination methods,respectively.The amino acid content is determined by an automatic amino acid analyzer.High performance liquid chromatography-diode array detector(HPLC-DAD)simultaneously analyzes the content of allantoin,uracil and adenosine.ResultsThe green fluorescent carbon dots were synthesized by microwave carbonization method.The best synthesis parameters were citric acid and urea ratio 1:5,precursor-to-liquid ratio 0.49:1,reaction time 4min15 s,high firepower heating,purification solvent was n-butanol.The particle size is concentrated at 3.5-5nm,the excitation wavelength is at 520 nm,and the emission wavelength is 524 nm.The carbon dot is stored in a refrigerator at4°C for twelve weeks,and the fluorescence can remain relatively stable within1 hour of continuous irradiation.Based on CDs/Fe3+ sensing system,the content determination of four kinds of yam samples was successfully realized.The contents were0.780±0.021μg/g,2.981±0.052μg/g,1.243±0.015μg/g and 0.940±0.008μg/g respectively.The contents of different components in yam samples treated with different foliar fertilizers were different.Samples treated with foliar fertilizer Y1 exhibited the highest yield of 401.07±19.7,followed by samples treated with Y5,S,Y4,Y3,CK,and Y2;the content of water in Chinese yam sprayed with foliar fertilizer Y2(77.5%)was the highest,followed by that treated with Y3、Y4、Y1 、 Y5 、 CK and S;the percentage content of polysaccharide in samples sprayed with foliar fertilizer S(3.6687%)was the highest,followed by that treated with CK,Y5,Y3,Y4,Y2,and Y1;the percentage content of protein in Chinese yam sprayed with foliar fertilizer S(4.0179%)was the highest,followed by that treated with Y1,Y5,Y4,Y3,Y2,and CK;the percentage content of total amino acid in Chinese yam sprayed with foliar fertilizer S was the highest,which was 2.0668%,followed by that treated with Y1,CK,Y3,Y4,Y5,Y2;The percentage contents of uracil and allantoin in Chinese yam treated with fertilizer S were higher than that of CK control group,which were0.0030% and 0.00108%,respectively.And the percentage contents of adenosine in Chinese yam treated by foliar fertilizer S and Y4 were higher than that in CK control group,0.00044% and 0.00066%,respectively.ConclusionsThe fluorescence quenching system of ferric ions based on carbon dots established in this paper is suitable for the rapid determination of ferric ions in yam samples.The experimental results show that the ferric ion pollution of planted yam is small and has good performance.safety.According to the results of the study,the contents of 7 main components in yam sprayed with different foliar fertilizers have changed.This change is expected to provide a valuable reference for the multi-purpose cultivation and daily application of a yam.