Study Of Liquid-liquid Interfacial Self-assembled AuNPs Arrays For Rapid And Sensitive Detection Of Paes By SERS

Objective: In recent years,a large number of pollution incidents of Phthalates plasticizers(PAEs)occur frequently.PAEs can enter the body through the skin,digestive tract,respiratory tract,and other paths,so that it will seriously endanger people's body.The conventional detection methods such as chromatography require complex sample preparation process,which are time-consuming,thus restricting the development of rapidly detecting PAEs.The Surface-enhanced Raman Spectroscopy(SERS),with narrow linewidth and molecular fingerprint features,can provide fast and sensitive detection for trace analytes.The purpose of this study was to develop a SERS active substrate by interfacial self-assembled Au nanoparticles(AuNPs)arrays for in situ,rapid and sensitive detection of PAEs.Moreover,three kinds of AuNPs with different sizes were assembled by the interface self-assembly method,and the relationship between the number of hot spots in per unit area and the SERS intensity was examined.Methods: Firstly,spherical AuNPs with the diameter of about 18 nm were prepared by the classical citrate method.The AuNPs arrays were prepared at cyclohexane/water interface by using AuNPs colloids as aqueous phase,the cyclohexane as oil phase,as well as the addition of the absolute ethanol as the inducer.We investigated the reproducibility and sensitivity of the AuNPs arrays by using crystal violet as a Raman probe.Then,we added butyl benzyl phthalate(BBP,a kind of PAEs)molecules to the commercial liquor,cyclohexane was mixed with liquor to extract the BBP spiked into liquor;the AuNPs arrays were assembled for detection of BBP molecules spiked into liquor by using supernatant CYH as organic phase.Moreover,the dual-analyte detection for BBP at organic phase and edible sunset yellow at aqueous phases was also investigated.Finally,the AuNPs arrays with lager size AuNPs prepared by seed growth method were prepared.Crystal violet was used as probe molecules to compare SERS intensity between three kinds of Au Ns arrays.Results:1.Spherical AuNPs with the diameter of about 18 nm were prepared by the classical citrate method.The highly close-packed AuNPs arrays were successfully assembled at liquid-liquid interface.The sensitivity of this SERS substrate for CV was low to0.04 ppm,the relative standard deviations(RSD)was 6.70%,indicating the high reproducibility and sensitivity of SERS measurements.The sensitivity of detection of BBP in ethanol solution was low to 0.1 ppm,and different types of commercial liquor spiked with 1.3 mg/kg BBP were detected,indicating the high sensitivity for BBP detection by using the self-assembly AuNPs arrays.Taking the advantages of interfacial assembly,the dual-analyte detection for BBP(30 mg/kg)at organic phase and sunset yellow(10 mg/kg)at aqueous phases was also realized with high sensitivity and credible reproducibility by this SERS platform.2.The diameter of about 45 nm and 60 nm AuNPs were prepared by seed growth method,and both AuNPs colloids were assembled at cyclohexane/water interface by method of interfacial self-assembly for SERS detection.The crystal violet was used as the Raman probe,the relationship between the number of hot spots at per unit area and SERS intensity was studied.The results of SERS detection showed that detection limit of AuNPs arrays self-assembled by 45 nm AuNPs was 0.02 ppm,which was lowest.The detection limit of AuNPs arrays self-assembled by 60 nm AuNPs was 0.04 ppm,which was equal to AuNPs arrays self-assembled by 18 nm AuNPs.On the reproducibility of SERS,AuNPs arrays self-assembled by 18 nm AuNPs exhibited the best reproducibility with the relative standard deviation of6.70%.The relative standard deviation of AuNPs arrays self-assembled by 45 nm and 60 nm AuNPs were 11.40% and 10.70%,respectively.This is due to the fact that the size of 18 nm AuNPs is the most uniform,and the gap between the particles is also uniform.Conclusions: In this experiment,we fabricated a Surface-enhanced Raman Spectroscopy(SERS)platform based on the self-assembled AuNPs at liquid/liquid interface for rapid detection of PAEs in the liquor.The BBP molecules extracted from liquor directly participates in self-assembly process of AuNPs,thus allows the analytes to be loaded onto SERS-active nanogaps,providing the sensitive detection for BBP.The study of the relationship between the number of hot spots at per unit area and SERS intensity shows that the SERS intensity does not increase with the number of hot spots increases,indicating that SERS activity is strongest at the appropriate number of hot spots.