【作者】 林海兰；

【导师】 蔡青云；

【作者基本信息】 湖南大学 ， 分析化学， 2010， 硕士

【摘要】 本论文主要针对目前严峻的环境污染问题,基于无线磁弹性传感器的质量响应原理并结合纳米技术,探索病原菌和持久性有机污染物的无线传感分析检测方法。无线磁弹性传感技术是基于磁致伸缩原理设计的,传感器由非晶态磁性材料和激励／检测线圈组成,在外加交变磁场中,磁性膜片受磁场激发产生磁矩,将磁能转换为机械能,并产生沿长度方向的伸缩振动,即磁致伸缩。当交变磁场的频率与磁性膜片机械振动频率相等时,膜片会产生共振,具有最大振幅,此时的振动频率即为磁性膜片共振频率。当磁性膜片传感器所浸入的检测溶液性质(黏度、密度等)或传感器表面负载质量发生变化时,其共振频率也会随之改变。磁传感器随其表面负载质量变化而变化的特性即为磁传感器的质量响应原理。由于磁性膜片本身是磁性的,其伸缩振动产生的磁通可通过检测线圈检测出。磁弹性传感器中信号的激发与传送通过磁场进行,传感器与检测仪器之间没有任何物理连接,属于无线无源传感器。磁弹性传感器这一特征使其在活体、在体分析、密闭容器中的无菌、无损检测等领域具有广泛的应用前景。随着纳米技术的发展,纳米材料因具有尺寸小、比表面积大等特性已开始渗入环境领域检测分析当中。.结合纳米粒子的特性和磁传感器无线无源的特点,开展环境中污染物的检测研究将是一件重大而有意义的工作。基于这个创新,本文主要做了以下三方面的应用研究工作：1)病原菌——大肠杆菌无线传感分析：以大肠杆菌为例,制备了磁弹性病原菌无线传感器；基于壳聚糖包裹的Fe3O4纳米粒子(CMNPs)与大肠杆菌的等电点不同,在一定的pH条件下,两者因带异种电荷而互相吸引,形成带磁性的病原体,再借助外加磁场的作用吸附到聚氨酯保护涂层的磁传感器表面,导致磁传感器负载质量增加,引起传感器共振频率减小；考察了不同CMNPs浓度对传感器响应的贡献,证实了交联剂戊二醛的引入能提高检测细菌的灵敏度；利用扫描电镜和透射电镜观察了细菌-CMNPs复合物在磁传感器表面的吸附情况,并获得了传感器对大肠杆菌的检测线性范围(10-3.7×108 cells mL-1),检测下限能达到10cells mL-1;基于CMNPs对大肠杆菌的静电吸附原理,考察了带电大分子(蛋白质)和较小分子(氨基酸及环境有机污染物)对传感器的干扰情况。结果表明,该方法对病原菌的检测有一定的选择性,在食品领域中检测病原菌具有广泛的应用前景。2)多环芳烃(PAHs)无线传感分析：采用腐植酸／壳聚糖复合物作为敏感层,以腐植酸(humic acid,HA)包裹的Fe304纳米粒子(HMNPs)作为信号放大工具,利用HA的疏水空腔对脂溶性PAHs的特异吸附性及包合性,在传感器表面形成HA/PAH/HMNPs的三明治结构,从而增加磁传感器的负载质量,导致其共振频率的下降；考察了磁传感器表面不同涂层,不同浓度的HMNPs以及体系pH对传感器响应信号的影响,获得了该传感器对六种美国优先监控的PAHs的检测线性范围和检测下限；由于PAHs结构上的差异,该方法对PAHs中的苯并芘和蒽的检测表现出一定的选择性,结果表明,苯并芘和蒽的检测下限分别可以达到3 nm和5 nm,表现出较高的灵敏度；同时考察了传感器对水环境中具有代表性的金属离子和有机污染物的响应情况,以此研究该传感器对PAHs的检测特异性。该传感器可用于水体中PAHs的分析研究,并具有富集PAHs的应用前景。3)苯并[a]芘(benzo[a]pyrene, BaP)无线传感分析：在PAHs无线传感器研究的基础上,改用氨基修饰的杯[4]芳烃作为敏感膜以提高其对特定PAHs的选择性。采用杯[4]芳烃修饰的金纳米颗粒作为信号放大工具,利用杯[4]芳烃的疏水空穴对BaP的特异包合作用,在磁传感器表面形成杯[4]芳烃／BaP／杯[4]芳烃-金纳米粒子的三重包合配合物,增加磁传感器的负载质量,获得对传感器响应信号的放大,检测下限达1.O×10-11M；考察了传感器对其他PAHs及水体中其他污染物的响应情况。中性有机物与杯[4]芳烃形成稳定性包合配合物取决于客体有机物分子结构与主体杯[4]芳烃疏水空穴的匹配情况,分析主体-客体分子结构可知,本实验选用的氨基修饰的杯[4]芳烃能与BaP形成稳定的2：1的包合配合物,因而对其表现出很好的选择性。所构筑的传感器能进行水样中BaP的检测。更多还原

【Abstract】 This dissertation is focused on the theoretics and the applications of the wireless magnetoelastic sensors. Environmental pollution is seriously global problems, especially caused by the pathogens and persistent organic pollutants (POPs). The wireless magnetoelastic technique is based on magnetoelastic principle, the sensor platforms consist of a magnetoelastic sensor and an exciting/a receiving coil. In response to a time varying magnetic field, the magnetoelastic sensor efficiently couples and translates magnetic energy to mechanical energy. The elastic energy mechanically deforms the sensor, causing it mechanically vibrate along its length. When the frequency of the ac field is equal to the mechanical resonance frequency of the sensor, the vibration amplitude is maximum, and the sensor vibrates at its characteristic resonance frequency that shifts in response to change of liquid properties (such as viscosity or density) or mass loading. Since the sensor material is also magnetostrictive, the mechanical oscillation in turn generates magnetic flux that can be remotely detected using a pick-up coil. The sensor is totally passive. No physical connections between the sensor and the detection system are required for signal telemetry, nor does the sensor require any internal power sources. The wireless nature of the magnetoelastic sensor makes it a powerful candidate for in situ and in vivo analysis. With the development of nano-technology, nano-materials due to its small size and large specific surface area and other features have begun to penetrate the field of environment among the detection and analysis. Combination of nano-particle properties and magnetic sensor wireless passive features, it will be a significant and meaningful work to research the detection methods of environmental contaminants. Based on this innovation, in this dissertation, three kinds of magnetoelastic biosensors were developed:(1) The development of wireless magnetoelastic pathogens sensor:Fabricate the wireless magnetoelastic pathogen sensor with Escherichia coli O157:H7 (E. coli) as a target using chitosan-modified magnetic Fe3O4 nanoparticles (CMNPs) as signal-amplifying tags; At suitable pH the CMNPs bind to negatively charged E. coli through electrostatic attraction. The E. coli attached CMNPs are magnetically bound to the surface of the magnetoelastic sensor, resulting in enhanced mass loading on the sensor surface that in turn decreases its resonance frequency allowing quantification of E. coli concentrations; investigate the sensor in response to the change of CMNPs and the effect of glutaraldehyde introduction; The sensor shows a linear response to the logarithmic concentration of E. coli in the range of 10 cells mL-1 to 3.7×108 cells mL-1, with a detection limit (LOD) of 10 cells mL-1; The sensor shows good selectively to bacterial detedction, as small molecules such as albumin bovine and ovalbumin show no interference on the detection.(2) The development of wireless magnetoelastic polycyclic aromatic hydrocarbons (PAHs) sensor:Fabricate the wireless magnetoelastic PAHs sensor with anthracene as the model target using humic acid-modified magnetic Fe3O4 nanoparticles (HMNPs) as signal-amplifying tags; A sandwich-type detection strategy involves the humic acid (HA)/chitosan composite self-assembled on the polyurethane-protected sensor surface and HMNPs, both of which flank the anthracene target in sequence. As the HMNPs-combined anthracene absorbs to the sensor surface, there is an increase in the mass load on the sensor, and consequently a decrease in resonance frequency; investigate the sensor in response to different coatings on the surface of magnetic sensors, different concentrations of HMNPs and pH; obtained the detection linear range and detection limit of six of the US Environmental Protection Agency (EPA) priority monitor PAHs; and investigate the sensor selectivity to PAHs by determining the sensor responses to some representative environmental pollutants; The highest sensitivity was observed in the response to benzo[a]pyrene and anthracene with LODs of 3 nM and 5 nM, respectively; the sensor can be used for detection of PAHs in water, and has the application prospect in enriching PAHs.(3) The development of wireless magnetoelastic benzo[a]pyrene (BaP) sensor: Based on (2), fabricate the wireless magnetoelastic BaP sensor using aminocalix[4]arene-modified gold nanoparticles (aminocalix[4]arene-Au NPs) as signal-amplifying tags; A sandwich-type detection strategy involves the aminocalix[4]arene self-assembled on the Au-protected sensor surface and aminocalix[4]arene-Au NPs, both of which flank the BaP target in sequence. As the aminocalix[4]arene-Au NPs-combined BaP absorbs to the sensor surface, there is an increase in the mass load on the sensor, and consequently a decrease in resonance frequency; investigate the sensor in response to different concentration aminocalix[4]arene-Au NPs, other PAHs and other pollution in water; as aminocalix[4]arene with BaP to form a stable 2:1 inclusion complexes, the sensor shows good selectivity to BaP detection and shows a detection limit of 1×10-11 M. The sensor can be used for detection of BaP in water.更多还原