The Application Of Fluorescent Nanoclusters Stabilized By Chicken Albumen And Peptides In The Analysis Of Metal Ions And Small Molecules

Due to their unique physical and chemical properties,noble metal nanoclusters are widely used in environmental monitoring,cell imaging,and medical fields.However,in the practical application,the detection of heavy metal ions and small biomolecules by noble metal nanoclusters still have problems such as poorer selectivity and time-consuming,which limits the broad application of the nanoclusters.In this thesis,we synthesized several different types of fluorescent nanoclusters,including chicken egg white stabilized silver and gold nanoclusters,histine stabilized gold nanoclusters and studied the analytical application of the nanoclusters in heavy metal ions small biological molecules by direct detection,masking agent and ligand exchange method.The results indicated that the method proposed here improved the selectivity and sensitivity of detection by using the nanocluster.The specific research contents are as follows:1.The uric acid level is an important indicator of human health that researchers widely study its analysis method.However,the traditional method for the detection of uric acid is usually complicated or have lower selectivity.In this thesis,chicken egg white(CEW)was used as a template for the synthesis of silver nanoclusters(Ag NCs).By studying the interaction between CEW-Ag NCs and uric acid(UA),we found that uric acid in the concentration range from 0.5?100 ?M could selectively and efficiently quench the fluorescence of CEW-Ag NCs linearly.Based on the specific interaction between nanoclusters and UA,a more rapid and simple method for the determination of uric acid in the was established.The method was also verified for practical sample detection in human fluids condition by standard addition method.2.Serum albumin is currently the most commonly used protein template for nanoclusters synthesis.To reduce the synthesis cost of nanoclusters,chicken egg white,which is purchased from a local market without further purification,was directly used to prepare fluorescence gold nanoclusters through a one-step,simple,fast,and green synthesis approach in aqueous solution.The as-prepared CEW-Au NCs has strong orange fluorescence emission,which can be quenched by mercury ions and copper ions sensitively.By using an EDTA masking method,mercury ions can be linearly detected with the limits of detection(LOD,3 o)of 0.510 ?M in the range from 0.60 to 10 p.M,within the presence of equivalent copper ions.3.Fluorescence of gold nanoclusters could be quenched by interacting with many heavy metals,such as mercury,copper,lead and so on.Thus,as an analytical probe,the detection selectivity of metal ions by gold nanoclusters is poor,especially for copper ions.In this thesis,two kinds of 10-atom Au nanoclusters with blue-green fluorescence were synthesized by ligand exchange method,and their applications in metal ion sensing were compared.It was found that the GSH-Au NCs which has fluorescence ermission hundred times higher than His-Au nanocluster,also has a highly selective quenching response to copper ion.Other common metal ions,such as Hg2+,Pb2+,Fe3+ and Zn2+,which could obviously quench or enhance the fluorescence of His-Au nanocluster,do not effect on glutathione-stabilized Au nanoclusters.We also discussed the possible quenching mechanism,studied the dynamic quenching process and also explored the application for Cu2+ detection.High selectivity detection of copper ions in the range of 0.5 to 300.0 ?M was achieved with a detection time of 5 min.At the same time,a visual detection method for copper ion,that may be used to warn whether the content of copper exceeded in waters by naked eyes observation was also be developed using the Au NCs probe.In summary,we synthesized several different types of fluorescent nanoclusters and studied the interaction between the nanoclusters and heavy metal ions,small biological molecules by direct detection,masking agent and ligand exchange method.The studies proposed here solved poor selectivity in analytical detection using the noble metal nanoclusters and realized selectivity detection of mercury ions,copper ions and uric acid in the real sample.