The Synthesis And Application Of Novel Fluorescent Probes Based On Platinum Nanoclusters

Metal nanoclusters?NCs?consisting of several metal atoms with narrow size distribution have been gaining much attention as novel fluorescent markers and considered to be effective candidates for organic fluorophore and quantum dots,owing to their excellent optical properties,sub-nanometer size and hypotoxicity.Compared with other NCs?Au NCs,Ag NCs and Cu NCs?,PtNCs have higher fluorescence quantum yield?QY?,being regarded as one of the future direction in NCs development.Recently,synthesis of PtNCs is focus in heating,stirring or etching methods.All the rational methods are time-consuming and the products are always unstable.Furthermore,applications of PtNCs just concentrate upon bioimaging field.Therefore,the designation of novel methods and development of application are two key issues in PtNCs researching.To solve these key scientific issues,in this dissertation,we have successfully synthesized BSA and/or PEI protected PtNCs as well asbimetallic Au/PtNCs by ultrasonic-assistant and hydrothermal methods.As fluorescence probes,these NCs have been applied in the detection of S^2-,nitroimidazole and tetracyclinemedicines.The contents are as follow:?1?Highly fluorescent?quantumyield,QY = 17 %?Pt16 nanoclusters?Pt16NCs@BSA?have been prepared via a one-step ultrasonic-assistance method by using cheap and easily available ascorbic acid as reductant and bovine serum albumin?BSA?as a stabilizing agent in aqueous solution.The fluorescence properties of the PtNCs@BSA can be easily controlled by optimizing conditions,and the products are extremely stable and could be used for the detection of sulfide ions(S^2-)in solutions as a specific luminescence sensor.The present synthesis method is performed in one step,being cost-effective with a particularly short reaction time,which could be extended to the synthesis of other kinds of protein-protected PtNCs.?2?A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine?PtNCs@PEI?is described.The products are characterized well by UV–vis absorption,fluorescence spectra,X-ray photoelectron spectroscopy?XPS?and high-resolution transmission electron microscopy?HR-TEM?imaging.The PtNCs@PEI possess high quantum yield at 28 %,which is the relatively high one among the reported PtNCs;especially,the synthesis is in one-step and the reaction time is much shorter?<1 h?than the related methods.In addition,the PtNCs@PEI has large Stocks-shift??150 nm?,high tolerability to the extreme p H and high ionic strengths,and excellent photo-stability under UV–vis irradiation,laid the foundation for the practical bio-applications.Finally,the obtained PtNCs@PEI are used to determine trace amount of metronidazole?MTZ?in buffer solution in showing a linear response over a concentration range of 0.25–300 ?M and a low detection limit of 0.1 ?M.Furthermore,the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probes to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body.?3?A novel fluorescence probe based on bimetallic Au/PtNCs protected by polythioetherimide?Au/PtNCs@PEI?is successfully fabricated using one-pot hydrothermal method.The reaction time is much shorter?< 1h?than the most methods of mono-and bi-NCs.The Au/PtNCs@PEI are characterized by HR-TEM,XPS,fluorescence lifetime and steady state spectrometer,UV/Vis/NIR absorption and fluorescence spectroscopy.The bimetallic NCs have large Stocks-shift?¹50 nm?,high tolerability to the extreme p H and high ionic strengths,and excellent photo-stability under UV-vis irradiation.In addition,the probe is used to detect the tetracyclines?TCs?on the basis of fluorescence quenching and distinguish chlortetracycline?CTC?well form other TCs in presence of Al³⁺,which increase the fluorescence intensity reversely.The linear response range for CTC is from 0.5 ?M to 30 ?M,and the limit of detection is evaluated to be 0.5 ?M.Finally,the strategy is successfully used to the determination of CTC in milk and the recovery ranged is test from 97.2 % to 102.7 %.