基于纳米结构阵列的SERS效应对痕量多氯联苯的快速检测

Polychlorinated biphenyls (PCBs) can cause harmful biological effects, and they can bio-accumulate in fatty tissues through food chains, so even small exposures eventually reach dangerous levels. Therefore, urgent actions have been called to dispose PCBs globally. Traditional laboratory techniques for the detection of trace PCBs include high-resolution capillary gas chromatographic columns with an electron capture detector, immunoassays, and high-resolution mass spectrometry. But these conventional methods are generally costly and time-consuming as tedious and complex pre-treatments have to be carried out. Rapid and sensitive detection of PCBs is therefore exigent and extremely important. Surface-enhanced Raman scattering (SERS) is one of the most powerful probing tools for rapid trace detection of organic chemicals because it enables ultrasensitive, low-cost and real-time detection. The nanometer-scale gaps, sharp tips and edges are believed to have highly concentrated electromagnetic fields associated with strong localized surface plasmonic resonance so that "hot spots" occur at these positions. For effective SERS substrates, it is generally required to have enough hot spots to ensure high SERS sensitivity, the uniformity of the substrate to ensure good reproducibility for SERS measurements, and the ability to capture the trace level PCBs molecules effectively. In this project, firstly large-area highly ordered arrays of noble metal solid/porous nanorods/nanopillars with tunable size and gaps between the adjacent nano-units will be achieved via ordered porous anodic aluminum oxide template-assisted synthetic approaches, and the arrays of semiconducting cone-shaped nanorods decorated with uniformly distributed noble metal nanoparticles on their surface will be fabricated on large-area planar Si or ITO substrate via seed-assistant growth approaches and subsequent sputtering. Secondly, SERS activity of the above-mentioned nanostructures will be investigated systematically by using R6G as probe molecules, based on which optimal arrays of nanostructures with highly sensitive SERS activity and signal reproducibility will be selected. Then the optimal arrays of nanostructures will be functionalized with a monolayer of mono-6-thio-β-cyclodextrin to effectively capture the apolar PCBs molecules in the hydrophobic cavity of the cyclodextrin. Lastly using the functionalized optimal nanostructures as effective SERS substrate, trace level of various congeners of PCBs will be investigated systematically. In addition, the mechanism of SERS effect and its relationship with parameters of the nanostructures will be studied and analyzed theoretically. The results will open a new door to the rapid detection of trace PCBs, lay foundation to the portable nanostructure-based device for on-line rapid detection of ultra-trace level PCBs, and therefore will be very important to the ecology environment and human health.

多氯联苯(PCBs)危及人类健康，且其危害具有累积性，痕量PCBs就会造成极大危害。目前实验室采用色/质谱等方法检测PCBs，需要萃取、浓缩、净化等繁琐的过程；虽然能实现痕量检测，但却无法实现快速检测。而痕量PCBs的快速检测至关重要，对突发、应急事件的预警与跟踪具有极其重要的意义。贵金属纳米结构的表面等离子体共振会引起局域场增强；当待检物吸附在其表面时，其拉曼信号强度会大幅度提高，产生表面增强拉曼散射(SERS)效应。由于拉曼光谱测量快，所以利用纳米结构SERS效应有望实现对痕量PCBs的快速检测。本项目将研究构筑SERS活性高、信号均匀、稳定、可重复的纳米结构的方法；筛选对PCBs特异性选择吸附的物质，并将其修饰在纳米结构表面，以便有效捕捉痕量PCBs；研究纳米结构对PCBs拉曼信号增强的规律与机理；为基于纳米结构SERS效应快速检测痕量PCBs提供科学依据，对环境健康具有重要意义。

多氯联苯(PCBs)是一类高毒性持久有机污染物，曾作为工业品大量使用。脂溶性的PCBs可经过食物链累积放大，痕量的PCBs就会造成极大危害。以色/质谱为代表的现有检测方法虽然能够实现痕量检测，但需要萃取、浓缩、净化等繁琐的过程，无法做到快速检测。贵金属纳米结构表面增强拉曼散射(SERS)效应可以大幅度提高吸附在其表面PCBs的特征拉曼峰强度，基于拉曼光谱的指纹特性和快速测量特点，利用纳米结构SERS效应有望实现对痕量PCBs的快速检测。本项目探索了有序多孔模板和无模板法构筑纳米结构阵列的技术；研究了纳米结构单元的形貌、尺寸和排列方式对SERS活性的影响机理和规律；筛选了能有效“捕捉”PCBs的物质，并研究了将其修饰在纳米结构阵列表面的方法；探索了实验室条件下快速检测痕量PCBs的可行性。项目组发展了构筑纳米结构阵列的普适方法和在纳米结构阵列上修饰生化物质的方法，获得SERS活性高、信号均匀稳定、对PCBs能有效“捕捉”的纳米结构阵列，初步实现了对痕量PCBs的准确识别与快速检测。顺利地完成了研究任务，实现了预期目标，为构建基于纳米结构阵列的SERS器件提供了科学依据、奠定了相关材料基础。相关研究结果共发表SCI论文27篇，其中影响因子(IF)大于3的有24篇，IF大于5的有14篇。包括国际功能材料类知名刊物Adv. Funct. Mater.一篇、纳米类知名刊物Nano Research两篇、Small一篇、Nanoscale三篇。有两篇论文以封面发表在Adv. Funct. Mater.和Nano Research上，有两篇论文以背封面发表在J. Mater. Chem. C和Analyst上。2013年发表在J. Raman Spectrosc.和Adv. Funct. Mater.的论文已分别被SCI刊物引用52次和25次，2014年发表在Nanoscale的论文已经被SCI刊物引用23次。同时，为了保护知识产权，相关研究结果共申请中国发明专利16项。