Surface-active Gels as Next-generation Chemical Sensors

从针对化学/生化战剂的平民保护到检测在毒品影响下驾驶的个人，一直需要灵敏和选择性的化学传感器。表面增强拉曼光谱(SERS)现在被认为是可能使执法机构迅速和明确地识别一系列化学威胁和目标的能力发生重大变化的技术之一。SERS的基础是通过用激光照射样品并测量从其散射的光的能量来确定样品的化学成分。对于未经处理的样品，有用的散射量通常很小，但在SERS中，通过将样品中的分子吸附到纳米尺寸的银或金颗粒表面来增强散射。在这个项目中，目标是开发一种系统的方法来处理这些增强颗粒，使它们对感兴趣的分子具有选择性，然后将它们保存到聚合物凝胶中，直到需要时，聚合物凝胶将被设计成按需释放活性颗粒。能够在现场几秒钟内检测到微量的重要化合物，应该能够更好、更快地做出应对恐怖主义威胁的决定。同样，快速检测微量目标化合物的能力可能会改变进行刑事调查的方式；路边药物测试就是一个明显的例子。这项建议的一个重要方面是首席调查员与北爱尔兰法医科学(FSNI)之间建立了良好的联系，后者自1999年以来一直积极与联合出版物合作，并直接赞助昆士兰大学的博士项目。这项合作主要涉及开发新的拉曼和表面增强拉曼光谱方法，用于分析非法药物、油漆、纤维、炸弹制造材料和其他物证。它已经导致了FSNI实验室内拉曼方法的常规使用，用于个案工作和毒品情报目的。在这个项目中，目标是现在采取下一步行动，将分析方法从实验室转移到现场测量。目标分子将是与化学/生物武器相关的，以及标准的刑事调查案件样本，但在NI内，这些都在FSNI的大部分覆盖范围内。与FSNI人员的互动对于向技术的业务方面提供重大投入至关重要，两名FSNI高级工作人员(分别来自危险物质和刑事调查领域)将成为项目组的一员。它们还将很好地向更广泛的用户社区提供反馈。新的传感器将需要比以前的任何材料对特定分析物更具选择性、更坚固和更灵敏，而且需要一个强大的跨学科团队来实现这一雄心勃勃的目标。在这个项目中，在纳米颗粒制备方面具有专业知识的拉曼光谱专家小组(化学)将加入药学院非常活跃的药物输送小组的两名成员的行列，该小组在开发聚合物凝胶作为药物配方载体方面享有国际声誉。在这里，这一经验将被用来设计按需释放纳米颗粒的表面活性凝胶(SAGE)。最后，化学工程师将把表面活性凝胶(SAGE)构建成平面阵列，每个目标具有不同的活性区域，或者将它们微胶囊化为刷片，通过物理压力破裂胶囊来激活。传感器设计和操作模式的灵活性使其成为一种具有多种应用的通用技术。归根结底，这项工作旨在为像呼气测定仪一样广泛使用的仪器奠定基础，这些仪器的灵敏度提高了几个数量级，可以在几秒钟内检测到选定的化合物。

There is a continuing need for sensitive and selective chemical sensors for applications from civilian protection against chemical/biochemical warfare agents through to detection of individuals driving under the influence of drugs. Surface-enhanced Raman spectroscopy (SERS) is now recognised as one of the technologies that may give a step change in the ability of law enforcement agencies to rapidly and unambiguously identify a range of chemical threats and targets. SERS is based on determining the chemical composition of a sample by irradiating it with laser light and measuring the energy of the light that scatters from it. For untreated samples the amount of useful scattering is usually very small but in SERS the scattering is enhanced by adsorbing the molecules in the sample onto the surface of nm sized silver or gold particles. In this project the goal is to develop a systematic method for treating these enhancing particles which makes them selective for molecules of interest and then to preserve them until required within polymer gels which will be designed to release the active particles on demand. The ability to detect trace amounts of important compounds within seconds in the field should allow better, faster decisions to be made in response to terrorist threats. Similarly, the capacity to rapidly detect trace amounts of target compounds could change the way criminal investigations are carried out; roadside drug testing is an obvious exampleAn important aspect of this proposal is the well established link between the principal investigator and Forensic Science, N. Ireland (FSNI) who have been actively collaborating since 1999 with joint publications and direct sponsorship of PhD projects in QUB. This collaboration has been mainly concerned with development of new Raman and SERS methods for analysis of illicit drugs, paints, fibres, bomb-making materials and other physical evidence. It has already led to routine use of Raman methods within the FSNI laboratories for casework and drugs intelligence purposes. In this project the goal is to now take the next step of moving the analysis methods out of the laboratory into field measurements. The target molecules will be chemical-/bio-weapons related, as well as standard criminal investigation casework samples but within N.I. both these are largely covered by FSNI. Interaction with FSNI personnel will be essential in giving a significant input to the operational aspects of the technology and two Senior FSNI staff members (one each from HazMat and criminal investigation areas) will be part of the Project Team. They will also be well placed to provide feedback to the wider user communityThe new sensors will need to be more selective, robust and sensitive for specific analytes than any previous materials and a strongly cross-disciplinary team will be required to reach this ambitious goal. For this project the specialist Raman spectroscopy group (Chemistry) who have expertise in the preparation of nanoparticles will be joined by two members of the School of Pharmacy's very active Drug Delivery group which has an international reputation in the development of polymeric gels as vehicles for pharmaceutical formulations. Here this experience will be used to design the surface-active gels (SAGEs) which release the nanoparticles on demand. Finally, a Chemical Engineer will build up the surface-active gels (SAGEs) into planar arrays with different active areas for for each target or will microencapsulate them to make swipe pads which are activated by rupturing the capsules with physical pressure. The flexibility in sensor design and modes of operation make this a generic technology with multiple applications. Ultimately this work is intended to form the basis for instruments that are as widely used as breathalyzers but have orders of magnitude improvement in sensitivity and can detect a chosen chemical compound in seconds.