Research And Application Of Fluorescent Silver Nanoclusters In Chemiluminescence System

Noble metal nanomaterials,which possess distinct optical,electrical,magnetic,thermal and chemical properties,were expected to provide new opportunities for the development of analytical chemistry.In recent years,nanomaterials have been applied in many fields including nanoelectronics,nanochemistry,biotechnology,environmental monitoring,medicine and so on.In this dissertation,we mainly focused on the noble metal nanomaterials unique optical capability and the specific analysis function of silver nanomaterials in chemiluminescence(CL)area of potential applications.The fluorescent silver nanoclusters(Ag NCs)were firstly applied in the enhancement of Ce(?)-Na2SO3 CL system.The main points of this thesis are outlined as follows:1.Fluorescent silver nanoclusters was synthesized using self-prepared PMAA as the template under photoreduction in a very simple,commercial and nontoxic approach.The Ag NCs were firstly applied in the enhancement of CL intensity.Results indicated that Ag NCs were excellent luminophors and energy acceptors in the enhancement of CL intensity.UV-Visible spectra,CL spectra and fluorescence spectra studies were carried out before and after the CL reaction to investigate the CL enhancement mechanism.It is proposed that the electronic energy of the excited state intermediate SO2*that originates from the CL reaction is transferred to Ag NCs to form an electronically excited Ag NC*whose emission is observed.2.Chemiluminescence was elicited in the system Ce(?)-Na2SO3 enhanced by Ag NCs in acidic condition,which was markedly inhibited in the presence of Cu2+ in this work.It was founded that Cu2+ quenched the emission by binding with the free carboxylic groups of PMAA polymers that surround the emissive Ag NCs,which then resulted in the reduced CL intensity.Based on these observations,a new CL method was developed for the Cu2+ in the range of 2.0 × 10-10?1.0 × 10-7 mol·L-1 with the detection limit of 1.2 × 10-10 mol·L-1.The possible CL mechanism of system was further explored.3.Cysteine is an important biologically active and thiol-containing compound.Cysteine inhibited the CL intensity of the Ce(?)-Na2SO3-Ag NCs system under suitable condition.By virtue of the specific response,a new,simple,and sensitive CL method for detecting cysteine has been developed.CL spectra,UV-Visible spectra and fluorescence spectra were acquired to investigate the possible CL mechanism.Cysteine binds onto the Ag NCs surface through the sulfur atom,remove the original carboxylic groups.The amount of carboxylic groups absorbed on the surface of Ag NCs might be reduced,which result in the inhibitive phenomenon.The present assay allows for the selective determination of cysteine in the range of 5.0 × 10"9 mol·L-1 to 1.0 × 10-6 mol·L-1 with a detection limit of 2.5 × 10-9 mol·L-1(3?).