Construction Of Novel SERS Nanoprobes And Its Application In Detection Of Heavy Metal And Pesticide Residues

Heavy metal and pesticide residues pose a serious threat to human health and the environment.The rapid detection and identification of them by efficient methods has great significance to practical needs and academic significance.In rencent years,Surface-enhanced Raman spectroscopy?SERS?can provide the characteristic vibrational fingerprint information on Raman spectroscopy by plasmon enhanced excitation and scattering.SERS technique has attracted increasing interest and been widely used in biomedicine,environmental monitoring,food safety and so on.More recently,a great deal of research effort has been devoted to construct novel nanoprobes in order to extract meaningful information with high sensitivity and selectivity.This paper provides a comprehensive idea to design two different types of nanoprobes based on noble metal?gold,silver?nanomaterials for application in heavy metal and pesticide residues.The main conclusions were as follows:?1?Fluorescent/SERS dual-sensing and imaging of intracellular Zn²⁺.Herin,we have developed fluorescent and SERS dual-mode probe for imaging of intracellular Zn²⁺based on N-?2-?bis?pyridine-2-ylmethyl?amino?ethyl?-2-mercaptoacetamide?MDPA?modified gold nanoparticles?MDPA-GNPs?.Benefiting from the chelation-enhanced fluorescence?CHEF?between MDPA-GNPs and Zn²⁺,the fluorescent intensities of MDPA-GNPs are substantially enhanced with the increment of Zn²⁺concentrations,which can be clearly observed by the naked eye.Under physiological conditions,the probe exhibits a stable response for Zn²⁺from1?M to 120?M,with a detection limit of 0.32?M in aqueous solutions.The resultant MDPA-GNPs can be used for ultrasensitive SERS detection of Zn²⁺because of the strong inter-particle plasmonic coupling generated in the process of Zn²⁺-triggered MDPA-GNPs self-aggregation,with a low detection limit of 0.28 pM,which is eight order of magnitude lower than the United States Environmental Protection Agency defined limit?76?M?in drinkable water.The intensity profile of the near field has been obtained through rigorously solving the Maxwell‘s equations.The Raman intensity of reporter molecule MDPA is significantly intensified due to the formation of SERS“hot spots”.More importantly,the proposed probe can be applied for efficient detection of intracellular Zn²⁺with excellent biocompatibility and cellular imaging capability.Therefore,a highly sensitive and selective nanosensor has been demonstrated for both reliable quantitative detection of Zn²⁺in aqueous solution and real-time imaging of intracellular Zn²⁺,suggesting its significant potential utility in bioanalysis and biomedical detection in the future.?2?Rapid and sensitive on-site detection of pesticide residues in fruits and vegetables using screen-printed paper-based SERS swabs.In this work,silver nanoparticles and graphene oxide were successfully prepared on cellulose paper?Ag NPs/GO paper?using screen printing technique.The screen printing ink containing graphene oxide and silver nanoparticles was orderly printed onto cellulose paper substrates by controlling the printing cycles to fabricate controllable SERS substrates in large batches for the detection of pesticide residues.It was found that up to four cycles,the SERS effect increased with the number of Ag NPs printing cycles and no obvious change was observed.The prepared Ag NPs/GO paper may exhibit a high enrichment ability due to the?-?stacking and electrostatic interactions of GO toward pesticide molecules.The results suggest that the high density of Ag NPs/GO on the prepared paper is enough for ultrasensitive SERS detection for thiram,thiabendazole and methyl parathion in complex surfaces with a low detection of 0.26 ng/cm2,28 ng/cm2,7.4 ng/cm2,which are much lower than the maximal residue limits in fruit prescribed by the U.S.Environmental Protection Agency.It is also friendly for environmental analysis as the SERS swabs can be burned after detection.Therefore,the sensitive SERS detection of pesticide residues based on Ag NPs/GO paper offers great potential for its practical applications in environmental analysis and food safety.