Study On The Synthesis Of Fluorescent Carbon Dots And Its Application For Metal Ions And Curcumin Analysis

In recent years,carbon dots as a new fluorescent carbon nanomaterial,have drawn great attention by the specialists in many countries.Compared with traditional organic dye molecules and semiconductor quantum dots,carbon dots have several advantages,such as tunable excitation and emission wavelengths,good light stability,resistant to photobleaching,no light flickering fluorescent properties,which made it have good potential applications in biochemical analysis,photocatalytic technology,bio-imaging,drug delivery,fluorescent probes and other areas.So far,great progress has been made in synthesis,modification,and luminescent property of carbon dots,exploring novel methods for large scale synthesis of carbon dots is still highly significative.T his article mainly explores new synthesis mothods of carbon dots,optical properties and their applications for the determination of chromium,curcumin and Pd2+.The main aspects are as follows:1.Fluorescent carbon dots for sensitive detection of Cr(?)in aqueous media and its application in test papersChromium(?)is proved to be highly carcinogenic and mutagenic and can exert an adverse impact on gene expression and cardiovascular system,leading to nephritis,dermatosis,various types of cancers,thus sensitive and rapid sensor for monitoring Cr(?)is in urgent demand.In this work,a facile fluorescent assay for sensitive and selective detection of Cr(?)was proposed using carbon dots(PCDs)from phytic acid and ethanediamine as nanoprobe.The obtained carbon dots are well dispersed,morphologically uniform with spherical shape,water soluble and stable with massive amino and hydroxyl groups on the surface.A series of experiments revealed that the quenching principle of the PCDs-Cr(?)system is a combination of IFE and static quenching.The present method provides the advantages of high sensitivity and selectivity,short testing time and so on.A good linear quenching was observed in the range of 1.0-400 ?M with a detection limit of 0.24 ?M(?/S = 3)under the optimized condition.The nanoprobe was employed for detecting Cr(?)in real water samples including river water and tap water with satisfactory recovery.Furthermore,the green fluorescence PCDs exhibited high biocompatibility,low cytotoxicity and can be used as fluorescent ink and biolabeling.Moreover,with the addition of Cr(?),the color changes of PCDs can be easily observed by the naked eye under a UV lamp,based on this,Cr(?)test papers were fabricated for spot quick detection of Cr(?).2.Sensitive chemosensor for Pd2+ using fluorescent carbon dots from natural materialAs a rare platinum-group element,Palladium has been widely used in fuel cells,jewelry,electronic device,catalysts and drug synthesis.Palladium is harmful to human health,such as leading to allergic reactions,DNA damage and inhibitory effect on the activity of enzyme.Therefore,sensitive and effective methods to detect trace palladium are significant.We proposed a sensitive fluoresc ence detection of Pd2+ using carbon dots as chemosensor.The CDs were synthesized via hydrothermal carbonization method using C hinese water chestnut as carbon source.The synthesized fluorescent CDs were characterized transmission electron microscopic(TEM),the results revealed the nanodots were well separated from each other.Besides,the CDs possess high fluorescence quantum yield,good chemical stability and stability against photobleaching,good water-solubility and biocompatibility.The fluorescence intensity of CDs can be obviously quenched in the presence of Pb2+.The decreased intensity was linearly correlated with the concentrations of Pb2+ in the range of 0.4-200 ?M(R2 = 0.9948).The detection method is simple,sensitive and accuracy.In addition,the CD-based probe was validated with real water samples with good spiked recoveries of 97.88%-103.27%.3.One-step hydrothermal approach to fabricate N-doped carbon dots and its application in the detection of curcuminCurcumin can not only be used as a coloring agent,but also be well applied in medical field due to its antioxidant,anti-inflammatory,anti-oxidant,anticarcinogenic,anti-microbial properties.Thus,investigation of the detection of curcumin with a sensitive assay is essential for clinical medicine and pharmacology.We have synthesized N-CDs based on chrysanthemum and ethanediamine via a one-step hydrothermal route.This method has several advantages,such as low cost,easy operation,green and none pollution,etc.we also studied the morphology of carbon dots and fluorescent properties and stable performance,etc.The strong blue emission of the N-CDs can be effectively quenched by curcumin based on IFE.The method is sensitive,fast and selective with a low detection limit of 20.81 ng m L-1.The proposed method has been successfully applied to detect curcumin in urine samples with the average spiked recovery of 97.50%-103.60%(RSD < 3.06%,n=3).