表面增强拉曼光谱检测硝基呋喃类抗生素

发布时间：2018-02-12 05:26

本文关键词： 表面增强拉曼光谱技术（SERS） Au溶胶磁性核壳材料硝基呋喃类抗生素　出处：《江南大学》2013年硕士论文　论文类型：学位论文

【摘要】：硝基呋喃类抗生素是一类广谱性抗菌药，包括呋喃唑酮（N1）、呋喃妥因（N2）、呋喃西林（N3）、呋喃它酮（N4），曾作为添加剂广泛应用于饲料及兽药之中，由于已被证实对动物体具有潜在的毒性、诱变性及致癌性，近年来已被各国陆续禁止使用。然而其价格低廉而药效明显，违禁使用硝基呋喃类抗生素的情况仍然不断曝光。表面增强拉曼光谱（SERS）是以拉曼光谱为基础，借助纳米材料表面的特殊光学性质，而获得物质分子指纹信息的一种技术；因其快速、无损、低耗、精确等优点，近年来在各科研领域发展迅速。本研究拟借助SERS技术，辅助纳米材料合成与修饰技术建立一种快速检测硝基呋喃类抗生素的方法。首先，通过密度泛函理论计算，对硝基呋喃类抗生素的特征拉曼振动进行理论分析，以为其定性提供理论依据。确定其拉曼特征振动主要为1602cm~(-1)处的C=N面内对称伸缩振动；1556cm~(-1)的NO_2非对称伸缩振动、呋喃环的对称伸缩振动；1484cm~(-1)处的呋喃环面内对称伸缩振动；1336cm~(-1)处的H-C-H对称伸缩振动、呋喃环摇摆振动；1220cm~(-1)处的C-N-N对称伸缩振动。其次，制备经典Au溶胶、磁性核壳纳米材料，对其形貌及检测条件进行分析，通过比较SERS增强效果确立最佳实验条件。一，在以Au溶胶为SERS活性基底时，应以丙酮为溶剂，待测样品与基底体积比为1:2，将体系pH值调至3.0~4.0之间，N1、N2、N4的最低检测限可达到5ppm，但N3无法检出，原因在于N3分子结构式的特殊性使其拉曼活性基团难以与Au溶胶表面充分接触。二，在以磁性核壳材料为基底时，应以Fe_3O_4@Ag为基底，Ag壳层厚度为40nm左右，基底在检测体系中的浓度为0.5g/ml，以633nm为激发波长，四种物质的最低检测限可达到0.1ppm。同时，通过分子组装技术在Fe_3O_4@Ag表面修饰了L-半胱氨酸，结果显示N3在该基底上可以获得更好的SERS效果。三，，从定性准确度、检测限、重现性等方面对上述两种基底的SERS效果进行了对比，总结认为基底Fe_3O_4@Ag的SERS效应最佳，因为Fe_3O_4@Ag的形貌、分布、间距更为规则均一，有利于激发SERS效应，且其Ag壳层表面的粗糙度更高，具有更大的表面积从而可以提供更多SERS活性位点。最后，对实际食品样品中的硝基呋喃类抗生素以加标提取的方式进行了SERS检测。由于食品体系较为复杂，对SERS检测存在一定的干扰，硝基呋喃类抗生素分子能够被增强的的特征振动较少，但分子结构中的主要振动即呋喃环、NO_2、C=N所有增强，表明该方法可对实际食品样品中硝基呋喃类抗生素实现简单的定性鉴别，在食品违禁添加剂的快速筛查方面具有一定的潜力。
[Abstract]:Nitrofuran antibiotics are a class of broad-spectrum antimicrobial agents, including furazolidone, furantoin, furantoin, furantoin, and furantadone, which have been widely used as additives in feed and veterinary drugs because of their proven potential toxicity to animals and animals. Mutagenicity and carcinogenicity have been banned by many countries in recent years. However, the use of nitrofuran antibiotics is still exposed because of its low price and obvious efficacy. Surface enhanced Raman spectroscopy (SERS) is based on Raman spectroscopy. A technique for obtaining material molecular fingerprint information by virtue of the special optical properties of the surface of nanomaterials, which has been developed rapidly in recent years because of its advantages of fast, nondestructive, low consumption and accuracy. This study is intended to be carried out by means of SERS technology. A rapid method for the detection of nitrofuran antibiotics was established by assisted synthesis and modification of nanomaterials. Firstly, the characteristic Raman vibration of nitrofuran antibiotics is theoretically analyzed by density functional theory (DFT). It is determined that the Raman characteristic vibration is mainly 1 602 cm ~ (-1). The NO_2 asymmetric stretching vibration is determined to be the symmetrical stretching vibration in the Con N plane (1556 cm ~ (-1)), and its Raman characteristic vibration is determined to be 1 602 cm ~ (-1) ~ (-1). The symmetrical stretching vibration of furan ring is 1 484 cm ~ (-1), the H-C-H symmetric stretching vibration of furan ring is 1336 cm ~ (-1), and the C-N-N symmetric stretching vibration of furan ring is 1220 cm ~ (-1). Secondly, the classical au sol and magnetic core-shell nanomaterials were prepared, and their morphology and detection conditions were analyzed. The optimum experimental conditions were established by comparing the enhancement effect of SERS. Firstly, acetone should be used as solvent when au sol was used as the active substrate of SERS. When the volume ratio of sample to substrate is 1: 2, the minimum detection limit of N _ 1N _ 2N _ 2N _ 4 can reach 5 ppm when the pH value of the system is adjusted to 3.0 ~ 4.0, but N _ 3 can not be detected because of the particularity of N _ 3 molecular structure which makes it difficult for the Raman active group of N _ 3 to fully contact the surface of au sol. When magnetic core-shell material is used as substrate, the thickness of Ag shell is about 40nm on Fe_3O_4@Ag substrate, the concentration of substrate is 0.5g / ml, the excitation wavelength is 633nm, and the minimum detection limit of four substances can reach 0.1 ppm. at the same time, L- cysteine was modified on the surface of Fe_3O_4@Ag by molecular assembly technique. The results show that N3 can obtain better SERS effect on the substrate. The SERS effects of the above two substrates are compared in reproducibility. The conclusion is that the SERS effect of the substrate Fe_3O_4@Ag is the best, because the morphology, distribution and spacing of the Fe_3O_4@Ag are more uniform, which is beneficial to stimulate the SERS effect. Moreover, the surface roughness of Ag shell is higher and the surface area is larger, which can provide more SERS active sites. Finally, the nitrofuran antibiotics in real food samples were detected by SERS with standard extraction. Because of the complexity of food system, the detection of SERS was interfered to a certain extent. The characteristic vibration of nitrofuran antibiotics can be enhanced less, but the main vibration in molecular structure is all enhanced, which indicates that this method can be used for simple qualitative identification of nitrofuran antibiotics in real food samples. There is a certain potential for rapid screening of food additives.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R155.5

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