Synthesis Of Doped Carbon Dots And Au Nanoclusters And The Application In Fluorescence Analysis

As a novel fluorescent nanomaterial,carbon dots have drawn tremendous attention due to their great optical properties,robust chemical inertness,low toxicity,and good biocompatibility.In addition,to promote the practicability of carbon dots,eco-friendly and simple precursors and preparation methods need to be developed.Based on the above analysis,we have carried out related research on the synthesis,property and application in analytical detection of novel fluorescent carbon dots.In addition,with the continuous advancement of the economy,a large number of harmful and toxic pollutants need to be paid attention and research in the environment,such as persistent organic pollutants.Some traditional methods have been used for detecting these pollutants,such as chromatography,electrochemical method,and atomic absorption spectroscopy.But these methods have the disadvantages of high cost,long time-consuming and cumbersome detection process,it is difficult to achieve rapid and effective determination.The ratiometric fluorescence method has developed rapidly in analysis because of its stability,high selectivity,high sensitivity and easy operation.In this work,a ratiometric fluorescence sensor is constructed based on bovine serum albumin-stabilized Au nanoclusters（BSA-AuNCs）.The main contents are as follows:Part 1:Green Synthesis of Blue Fluorescent P-doped Carbon Dots for the Selective Determination of Picric Acid in an Aqueous MediumA fluorescence method for the determination of picric acid（PA）using phosphorus-doped carbon dots（P-CDs）,synthesized from beta-cyclodextrin and sodium pyrophosphate,is described.The P-CDs are very uniform and monodisperse with a diameter of about 2.8 nm.Under an excitation of350 nm,the P-CDs emit bright blue fluorescence with an emission peak at 440 nm.The as-synthesized P-CDs serve as a sensitive,selective,and label-free fluorescent probe for the detection of PA.Based on an inner filter effect between PA and P-CDs,a linear response is obtained for PA from 0.1 to 10μM with a detection limit of 82 nM.Finally,this sensing system has been demonstrated to have practicability for PA detection in the environmental water samples.Part 2:Proton-controlled synthesis of red-emitting carbon dots and application for hematin detection in human erythrocytesThe red-emitting nitrogen-doped carbon dots（N-CDs）are synthesized using o-phenylenediamine by a one-step method,which can serve as a fluorescent probe for“turn off”detection of hematin in human red cells.The red-emitting N-CDs can be obtained only in an acidic condition and the emission of the red-emitting N-CDs is pH-dependent,indicating a proton-controlled synthesis and emission.The red-emitting N-CDs are 2.7 nm in mean size and have a uniform dispersion and exhibit a high quantum yield（12.8%）and great optical property.The developed sensing system for hematin displays a linear response from 0.4 to 32μM with the detection limit of0.18μM.Importantly,this fluorescent probe demonstrates a good potential practicability for the quantitative detection of hematin in the complex matrixes.Part 3:Ratiometric fluorescence method for malachite green detection based on dual-emission BSA-protected gold nanoclustersThe ratiometric fluorescence measurement has drawn great attention due to its selective and sensitive sensing property for numerous analytes.In this sensing system,a ratiometric fluorescence method is described for the determination of malachite green（MG）based on bovine serum albumin-stabilized Au nanoclusters（BSA-AuNCs）with dual emission.The as-prepared BSA-AuNCs exhibit two emission peaks around 430 and 610 nm under a single excitation,which may be from the intrinsic structure of BSA and AuNCs,respectively.As MG was added,the fluorescence at 610 nm was obviously quenched,and the fluorescence intensity at 430 nm decreased slowly,which might be mainly ascribed to fluorescence resonance energy transfer and dynamic quenching.The fluorescence intensity ratio of F₄₃₀/F₆₁₀ shows good linearity for detecting MG in the 0.3-20μM range with a low detection limit of 0.19μM.In addition,the ratiometric sensing strategy is successfully applied to real water samples,which reveals its potential practicability for detecting MG in environmental water samples.