| In recent years,environmental pollution and food safety are increasingly threatening to human health with the continuous development of light industry.The use of food additives（such as pigments）in food industry and organic dyes in textile and printing industries directly endangers human health.Therefore,the detection of food additives and organic dyes is particularly important.At present,the developed detection methods include fluorescence spectroscopy,electrochemical method,surface enhanced Raman scattering（SERS）spectroscopy,etc.Among them,SERS spectroscopy has attracted much attention in the field due to its simple operation,short detection time and high detection sensitivity.With the development of SERS substrates,SERS technology has become one of the main methods to detect pigments and organic dyes.In this dissertation,SERS technology was used as the main research method to realize the rapid and sensitive detection of food additive tartrazine,organic dye Rhodamine 6G（R6G）and crystal violet（CV）.The preparation of SERS substrates is one of the most important factors for SERS technology.Three kinds of SERS substrates were prepared,including gold nanoparticles（Au NPs）,gold nanostar（Au NSs）films and Au NPs doped molybdenum disulfide（Au-Mo S2）substrates.Based on the electromagnetic enhancement（EM）caused by the local surface plasmon resonance（LSPR）effect of noble metal nanomaterials and the chemical enhancement（CM）effect caused by two-dimensional semiconductor materials,the Raman signals of the target molecule were obviously enhanced,achieving the highly sensitive detection of tartrazine,R6G and CV.The main research contents are as follows:1.Ascorbic acid（AA）-functionalized anti-aggregation Au NPs,prepared by seed-mediated method,were successfully used as fluorescence and SERS probes for ultra-fast,highly selective and highly sensitive detection of tartrazine in a wide detection range.Tartrazine emitted fluorescence at～547 nm when excited at 361 nm.The emission peak intensity was obviously enhanced upon addition of Au NPs due to the metal-enhanced fluorescence（MEF）effect.The detection linear range was between2.0-40.0μM and the limit of detection（Lo D）was 15.4 n M.In addition,the SERS signal intensity was gradually increased with an increase in tartrazine concentration over a range of 1.0×10-11-1.0×10-7 M and the Lo D was 8.0×10-13 M.The prepard Au NPs can effectively detect tartrazine in commercial beverages by fluorescence and SERS techniques,providing a new method for highly sensitive detection of tartrazine in real samples.2.Au NSs prepared by seed-mediated method was deposited on a glass covered with polydiallyl dimethyl ammonium chloride（PDDA）by electrostatic adsorption to obtain Au NSs thin film,which was used as SERS substrate to detect R6G,CV and their mixed solution.The Au NSs tfilm successfully enhanced SERS signals of R6G,CV and mixed solution by EM effect.The results demonstrated that the Lo Ds of R6G and CV were3.0×10-10 M in the range of 1.0×10-9-1.0×10-4 M.The prepared substrate showed good uniformity,and the relative standard deviations are 11.01%and 16.75%,respectively.In addition,R6G and CV in mixed solution can be qualitatively detected by SERS technique.Therefore,the prepared Au NSs substrate can be used for rapid detection of R6G and CV,constructing a new platform for the detection of other organic dyes.3.Au NPs prepared by trisodium citrate reduction method was dripped on the hexagonal Mo S2 thin film prepared by chemical vapor deposition（CVD）,realizing the rapid and highly sensitive detection of R6G by using it as a SERS substrate.The prepared SERS substrate was composed of two-dimensional semiconductor material Mo S2 and nanomaterial Au NPs.Therefore,the SERS signal of R6G was successfully amplified by the EM effect of Mo S2 film and the CM effect of Au NPs,and the Lo D was3.0×10-13 M.The prepared substrate showed good uniformity,and the relative standard deviation was 14.22%.Therefore,the prepared Au NPs doped Mo S2 substrate can be used to detect R6G with high sensitivity,which provides a new strategy for the detection of other organic dyes. |
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