| In recent decades,a large number of research team have contributed to the prepared of a variety of surface enhanced Raman scattering(SERS)substrates to enhance the Raman signal of the target analytes.Especially,silver(Ag)and gold(Au)nanostructures have been widely used because they have high plasmonic activities in the range of visible near-infrared regions.However,the uniformity of enhancement efficiency of ordinary SERS substrate cannot be guaranteed due to the degree of agglomeration of metal nanoparticles is difficult to control and measure.To overcome these disadvantages,it is necessary to develop a SERS substrate with uniform,controllable and reproducible structure.Therefore,in this paper,we introduced the polydopamine(PDA)which has many special properties,such as adhesive,reactivity,adsorption,reducing,chelation,hydrophilicity and so on.The stimulus responsive poly N-isopropylacrylamide(PNIPAAm)combined with the noble metals of Ag and Au,the prepared of three different dynamic SERS substrates by simple and effective method and realization of pesticides,organic dyes,organic pollutants and quantitative detection in situ.Specific content are as follows:1.We reported a simple and fast method to prepare a composite material of polydopamine(PDA)adlayer covered cubic AgCl core,which was inlaid with Ag nanoparticles(NPs),shortly named as AgCl/ PDA /AgNPs.The resultant AgCl/ PDA/AgNPs could be employed as Surface-enhanced Raman scattering(SERS)substrate for in-situ detection and the SERS activity could be further greatly improved due to the production of more AgNPs upon laser irradiation.With 4-mercaptopyridine(4-Mpy)as the probe molecule,the enhancement factor could reach 107.Additionally,such SERS substrate shows good reproducibility of detection with relative standard deviation at 7.32% and long term stability(after storage for 100 days under ambient condition,SERS intensity keeping more than 75%).In-situ elevating SERS activity of AgCl/PDA/AgNPs inducing by laser may be beneficial to sensitive analysis in practical fields.2.Since the above composite have reactivity due to the existence of PDA on the surface.It is easy to be modified by sulfhydryl containing temperature sensitive poly(N-isopropylacrylamide)(PNIPAAm-SH)to become a multi stimulus responsive dynamic SERS substrate.The addition of halide salts to the modified SERS substrate(AgCl/PDA/AgNPs@PNIPAAm)system can not only induce the phase transition of PNIPAAm at room temperature,but also enrich the trace material,which leads to the further enhancement of the SERS signal of the analyte.Therefore,the substrate can be used for the detection of methylene blue(MB)and the detection limit could reach1 pM.Our findings may be contribute to the development of the green and low-cost SERS substrates and will allow the fast and quantitative detection of trace organic molecules.3.We present the synthesis of polydopamine particle-gold composites(PDA-Au)and unique release of AuNPs@PDA core@shell nanoparticles(NPs)from the PDA-Au upon external stimuli.The PDA-Au was prepared by controlled synthesis of AuNPs on the PDA particles.Upon ultraviolet irradiation or ultrasonic treatment on the PDA-Au,the synthesized AuNPs within the PDA could be burst-released as a form of AuNPs@PDA.The PDA-Au composite showed outstanding photothermal conversion ability under ultraviolet irradiation due to the ultrahigh loading of the AuNPs within the PDA,leading to a remote-controlled explosion of the PDA-Au and rapid formation of numerous AuNPs@PDA.The release of the AuNPs@PDA could be instantly stopped or re-started by off or reboot of ultraviolet,respectively.In addition,we completed a qualitative and quantitative detection of PAHs in water environment due to the presence of ?-? interactions between PAHs and PDA on the surface of AuNPs@PDA.Thus we demonstrated that the PDA-Au NPs exhibited excellent and sustained performances for the detection of PAHs in water due to its capability of the continuous production of fresh AuNPs@PDA during the reuse. |
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