| Metal nanoclusters(MNCs)has unique properties such as strong light stability,large Stokes shift,low toxicity and so on.In addition,the synthesis process of metal nanocluster is simple to operate.The nanoclusters with different particle sizes and luminescence performance can be prepared by controlling the synthesis conditions.In this paper,the natural biomolecules-silk fibroin(SF)was used as protective agent to prepare copper nanoclusters(Cu NCs),silver nanoparticles(Ag NPs)and nickel nanoclusters(Ni NCs).And based on the mechanism of aggregation induced emission(AIE),nano etching,and fluorescence quenching,p H,ion,and molecular sensing system are established,respectively.Chapter 1: We summarized the synthesis,properties and applications of MNPs.And we briefly proposed the work content of this paper.Chapter 2: A simple one-pot green method synthesized fluorescent silk fibroin(SF)protected copper nanoclusters(Cu NCs)possessing unique aggregation/assembly induced emission enhance(AIEE)characteristics with the assistance of sulfide ion in aqueous solution.The interaction of Cu NCs with S2-was further investigated by fluorescence spectroscopy,UV–vis absorption spectroscopy,X-ray photoelectron spectroscopy(XPS),and Fourier transform infrared(FTIR)spectroscopy.It demonstrated that the S2-can induced the ultrasmall Cu nanoclusters of ca.2.8 nm orderly assembled to large nanoparticles of uniform rod-like with the size(47.5 ± 2.2)×(15.3 ± 2.2)nm by transmission electron microscopy(TEM).And the fluorescence intensity of the dispersed Cu NCs was increased with the increase of absolute quantum yield from 1.6% to 4.9%.More importantly,the assembly large Cu nanoparticles are also monodispersed in size and morphology,which provides a distinctive advantage for analytical applications.Based on this,SF@Cu NCs can be developed into a practical nanosensor for “turn-on” luminescence detection for S2-with a highly sensitive and selectivity.The linear response with the S2-concentrations range from 5.0 μM to 110.0 μM and detection limit was 0.286 μM.We demonstrated this assembled nanostructure as a powerful analytical platform for S2-detection.Chapter 3: An environmentally friendly approach to synthese the fluorescent Ag NPs was presented with the protecting agent of silk fibroin protein(SF)in alkaline conditions.The bifunctional nanoprobe were employed for S2-and p H sensor.With the addition of S2-,an impressive luminescence enhancement of SF@Ag NPs was observed.And TEM showed that the larger particle size Ag NPs were etched into small size Ag NCs.Therefore,the synthesis SF@ Ag NPs was higher selectivity to S2-and can be used ratio sensor to determinate S2-.Moreover,the SF@Ag NPs can be also developed into a p H sensor baseing on the protonation and deprotonation mechanisms of SF@Ag NPs.The fluorescence of SF@Ag NPs enhanced with the increasing of p H,and the size of Ag NPs were etched into small size.So,this study provides new ideas for the investigation of single probes for multiple target detection.Chapter 4: Fluorescent nickel nanoclusters(Ni NCs)was successful prepared using SF as the template.The prepared Ni NCs possessed strong blue-green fluorescence and higher quantum yield of 15.26%.It can be used to detected the H2O2 and tetracycline(TCs)in aqueous solution with different signal response.The fluorescence peak of the probe changed proportionally with the addition of TCs.The fluorescence intensity of SF@Ni NCs decreases at 475 nm,while the fluorescence intensity at 525 nm increases with the concentration of TCs,and one iso-emission point occurs at about 500 nm.However,the fluorescence spectra of SF@Ni NCs at 475 nm was quenching by H2O2.Therefore,this method can be used to detect TCs and H2O2.In addition,the synthesized SF@Ni NCs have low toxicity to enter cells,which makes it possible to be further applied in the field of bioimaging.Chapter 5: The metal nanoparticles as fluorescent sensing in the detection of ion、p H and molecule in this paper is summarized,and the related future work is narrated. |
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