Preparation And Application Of Silver Nanoparticles Wrapped By Polyethyleneimine As SERS Substrate

The character of Surface enhanced Raman spectroscopy is high sensitivity,simple operation,quickly analysis,and so on.In recent years,Surface enhanced Raman spectroscopy has rapidly developed in the analysis of detection,and was widely used to detecting enviro nmental pollution,biological molecules,such as cancer marker.Substrate is the key to surface enhanced Raman spectroscopy,build a stable and efficient substrate is the precondition of this technology is used in practical application.In this paper,we prepared silver nanoparticles which is wrapped by polyethylenei mine(Ag@PEI NPs),this kind nanoparticle has high antioxidant property and build a new SERS substrate(Ag@PEI-FP-3),which the nanoparticles are assembled on the surface of filter.The new substrate has successfully used to detect Anionic dyes in food.In this article,polyethylenei mine(PEI)was chosen as reducing agent and protective agent,the reaction vessel of hydrothermal method has replaced by head space bottle,the Ag@PEI NPs,which is uniform morphology,size distribution and strong oxidation resistance,has prepared by one-step.At same time,Ag@PEI NPs has strong antioxygenic property.Because this silver nanoparticle was prepared through the strong interaction between silver and nitrogen which is from PEI,nano-silver was wrapped by a large of PEI,which have much positive charged.One of the result is that made zeta potential of Ag@PEI NPs increasing(up to +44.3 ± 5 mV),so this substrate is suitable for the detecting of organic anionic or inorganic anionic ion.Another result is that,due to the large electron-donating group-N in PEI,it can effectively prevent silver nanoparticles from being oxidized.Exposed in air for three month,Ag@PEI NPs is still can keep enhancement activity.In order to further improve the sensitivity and application of Ag@PEI NPs in analysis of detection.In this article.combining or assembling Ag@PEI NPs on fiber base material with negative charged through the electrostatic interaction of the negatively charged of fiber and the positively charged of Ag@PEI NPs.Comparing the SERS enhancement ability,signal uniformity and operability of practical application of Ag@PEI-activated carbon(Ag@PEI-AC),Ag@PEI-cotton wool(Ag@PEI-CW),Ag@PEI-cotton cloth(Ag@PEI-CC),Ag@PEI-filter paper(Ag@PEI-FP-1)was prepared through in situ growth method,and Ag@PEI-FP-2,Ag@PEI-FP-3 prepared through adsorption.It's found that Ag@PEI-FP-3 is the best.The filter paper of Ag@PEI-FP-3 was pretreated by NaOH,that made filter paper fibers are fluffy,and is beneficial to making Ag@PEI NPs to enter into fiber layer and form a three-dimensional substrate,and the sensitivity has greatly increased.Using Ag@PEI-FP-3 as the substrate to establish a analysis method of detecting anionic dyes brilliant blue and amaranth,the concentration of brilliant blue exists a good linear relationship between Raman intensity in the range of 0.001~10 ppm,with a detection limit of 0.5 ppb.Use this method to detect the content of brilliant blue in Fanta,which has a lot of amaranth,without any pretreatment,measured the standard addition recovery rate of brilliant blue was 100.4% ~ 100.4%;In Fanta,the concentration of amaranth exists a good linear relationship between Raman intensity in the range of 0~10 ppm and the concentration of amaranth in Fanta is 7.62 ppm.