The Preparation Of Silver Nanomaterials For The Detection Of Phenolic Pollutants

Nanometer materials is a new type of material rising from the last century,it is defined that the scale of the material in the three-dimensional space at least one-dimensional within the scope of nanoscale,and we know that the scope of nanoscale materials is usually composed of several to hundreds of thousands of atoms of a collective,research shows that when the nanometer materials size reduces to a certain value,due to the quantum size effect and small size effect,the electronic energy near the Fermi level is separated and quantized,and the materials will emission fluorescence when the materials was excitated.Quantum dots and nanoclusters are two kinds of newly nanometer fluorescent materials,compared with the traditional fluorescent materials,good luminous performance and resistance to photobleaching,quantum dots,and the broad excitation peak can realize synchronous excitation that use one excitation light to achieve different emission peaks of quantum dots,and narrow emission peak also could reduce the interference of other emission peaks,thus it can be used for multi-color mark,which would greatly promote the application of quantum dots in many fields.Nanoclusters,another fluorescent nanomaterial,it is different from quantum dots,consist of an number of atoms or ions by a specific form to form a microstructure,compared with quantum dots,although the excitation peak is narrower and the emission peak is wider than quantum dots,the good luminous performance and resistance to photobleaching,good biocompatibility,mild synthetic conditions,less using of the poisonous and harmful heavy metals made it widely used in many fields.On the basis of silver fluorescent nanomaterials,this work introduced three new methods of nanomaterials and their applications in the fluorescence analysis field.1)We used sulfur powder and hydrazine hydrate reacted to get a new form of sulfide,on the premise of the glutathione(GSH)as the modifier,GSH and sulfide was used to react with silver nitrate to synthesis new near infrared Ag2S quantum dots.In order to obtain the best experiment condition,we investigated the synthesis and analysis conditions of the fluorescence analysis with bisphenol A.Since the dosage of modifier could reflect on the particle size and fluorescence emission peak range of the final synthesis of quantum dots,this part would focuse on the investigating of the proportion of silver and the modifier by exploring the various synthesis conditions,When the concentration ratio of AgNO3:GSH at 10:25,we find that the fluorescence quantum dots had a better fluorescence and the emission was located in near infrared region,the Ag2S QDs also had a fluorescence response with bisphenol A,at the same when the pH of salutation is 4,the fluorescence response is the largest,the equation for fluorescence detecting is F0/F = 0.086 CBPA + 0.9697,and the linear correlation coefficient is 0.9811,the infrared spectra before and after reaction showed that the synthesis mechanism for silver nanoclusters is glutathione combined with Ag and sulfhydryl,the results of fluorescence detecting bisphenol A indicated that fluorescence response was matched with Stern-Volumer equation which indicated that the mechanism is a dynamic quenching mechanism and the good recovery rate in the environment samples also showed that it had a good practicability.2)We synthesized the silver nanoclusters with a rapid reaction,sodium borohydride used as reducing agent,we carry out the synthesis reaction of silver nanoclusters for fluorescent probes with different raitos of silver nitrate and bovine serum albumin(BSA),which had a fluorescence response of nitro phenol,the difficulity of this part is the proportion of modifier and silver which could affect the fluorescence peak,when the concentration of nitric acid silver and modifying agent are all 5 mM,and the pH was 8,the fluorescence response with nitro phenol was best,and the linear correlation coefficient of the detecting equation was 0.9901,which indicated a better precision,and the fluorescence response which matched with Stern-Volumer equation showed that the fluorescence quenching was a dynamic quenching mechanism.High sensitive,strong anti-jamming capability and good recovery rate showed that material had a good practicability and high potential of application.3)Although the siver nanoclusters have many advantages,it also could be interference easily by the environment in the fluorescence analysis and the silver nanoclusters had difficulity in the recognition of the analogue analyte,in order to improve the selectivity and expand the application of silver nanoclusters,we introduce a new method to synthesize the fluorescence probe,in this work we combined molecular imprinting technique with silver nanoclusters,the GSH moderfied silver nanoclusters was used as the fluorescent signal source,bisphenol A(BPA)used as template molecule,3,ammonia propyl-triethoxy silane(APTES)was functional monomer,ethyl orthosilicate(TEOS)was crosslinking agent and acetic acid worked as the catalyst,we used sol-gel method to synthesize the molecularly imprinted polymers which have a specific recognition ability of bisphenol A,the highlight and difficulty of this experiment were the ratio of polymers and silver nanoclusters.We carried out a series of experiments to obtain the best reacted parameter,and UV-vis,FTIR,nuclear magnetic,TEM and other testing means were used to investigate the reaction mechanism during the process of preparation and detection mechanism has carried on the exploration of bisphenol A,UV-vis and nuclear magnetic were used to make sure whether the template molecules had been removed completely or not,TEM,SEM showed that synthetic material of uniform particle size,and the size is about 200 nm,infrared spectra showed that the mechanism of before and after synthesis,the glutathione reacted with Ag through the thiol group,UV-vis spectra showed that the molecular imprinting polymer detection of bisphenol A(BPA)is an electron transfer mechanism,and then we also successfully applied it to the practical samples recovery tests,the difficulty of this part of the experiment is the controlling of the proportion of nano clusters and the polymer due to the proportion had a directly influence on the sensitivity,accorded to the experiment,when the synthesized volume ratio of silver nanoclusters and MIP(V(APTES):V(TEOS)= 1:1)is 5:0.5,the selectivity of system with bisphenol A is best,and the polymer imprinting factor of bisphenol a is 4.5,in the standard recovery test samples,the high imprinting factor and good recovery indicated that the new preparation of fluorescent probes had a good practical value and application prospect.