Responsive surfaces: Lanthanide based Langmuir-Blodgett mono-layers for the sensing of chemical warfare agent mimics

传感器在社会中发挥着重要作用，其应用范围包括环境监测、临床生物学（例如疾病标志物检测）、食品安全（例如污染物的检测）、防御（例如实时生物和化学战剂（CWA）检测、爆炸物检测）、核工业（例如辐射和温度传感器）和工程/航空电子设备（例如温度和压力传感器、表面损伤传感器），仅举几例。在所有情况下，早期发现或感知变化至关重要。传感器开发的一个特别重要的应用是在CWA感测领域。有机膦酸盐神经毒剂的剧毒性质以及军人和平民接触的可能性是一种真实的危险。可以理解的是，军事人员和平民群体都明确需要有充分的实时探测能力，提前发出暴露警告将有助于防止伤亡。目前用于感测有机膦酸酯的分析技术虽然是高度灵敏的，但具有一些明显的局限性，包括复杂的仪器、不方便的样品制备、缺乏便携性和高成本。这些缺点在一定程度上阻碍了易于集成到个人防护设备中的基于成本有效的现场的便携式装置的开发（例如智能纺织品）和用于公共区域的非侵入式检测器。已经开发的一种克服这些问题的方法是通过与响应材料的相互作用来测量信号变化，所述响应材料经历化学、电、暴露于化学衍生物时的光学或磁性。作为一般传感器开发的响应介质的发光已经受到显著的关注，特别是在过去的5 - 10年中已经开发了一些优雅的发光超分子系统用于检测CWA及其模拟物。这些传感器中的大多数是基于溶液的传感器（这限制了在装置中的使用-溶液不方便储存，经常遭受不稳定性并且样品制备可能是麻烦的-参见上文），并且考虑到基于现场的应用，需要从溶液响应系统转移到基于表面固定的受体-报告子的传感器。这代表了该领域的一个重大差距，因为发光传感为固定传感器提供了一种有吸引力的媒介，具有从简单组件开发小型便携式设备的潜力。因此，我们将使用另一种方法来克服上述一些缺点。通过利用薄膜（单层）镧系元素基传感器，其中传感器沉积（固定）到表面上（使用Langmuir-Blodgett技术）并且在暴露于低水平的CWA模拟物时经历发光性质的变化，我们将克服上面列出的限制。在整个研究项目中，我们将探索这种替代方法对CWA模拟物的选择性和敏感性，并最终评估其纳入功能性器械的适用性。因此，我们结合镧系元素的上级物理性质和由Langmuir-Blodgett技术提供的对沉积的控制的方法将产生设计的镧系元素发光传感器，其可以容易且可靠地固定，潜在地改变表面分子传感领域。

Sensors play an important role in society, with applications in a variety of circumstances including environmental monitoring, clinical biology (e.g. disease marker detection), food safety (e.g. detection of contaminants), defence (e.g. real-time biological and chemical warfare agent (CWA) detection, explosives detection), the nuclear industry (e.g. radiation and temperature sensors), and engineering/avionics (e.g. temperature and pressure sensors, surface damage sensors) to name just a few. In all cases the early detection, or sensing, of change is paramount. One particularly important application of sensor development is in the field of CWA sensing. The highly toxic nature of the organophosphonate (OP) family of nerve agents and the potential for exposure to both military and civilian populations represents a real danger. Understandably, there is a clear requirement for adequate real-time detection capabilities for both military personal and civilian populations where advanced warning of exposure will help prevent casualties. Current analytical technologies for sensing organophosphonates, whilst being highly sensitive, have some clear limitations including complex instrumentation, inconvenient sample preparation, lack of portability, and high cost. These drawbacks somewhat hinder the development of cost-effective field based portable devices that are easily integrated into personal protective equipment (e.g. smart textiles) and non-invasive detectors for use in public areas.One approach that has been developed to overcome these problems is to measure signal change through interaction with responsive materials that undergo changes in chemical, electrical, optical or magnetic properties on exposure to chemical derivatives. Luminescence as a responsive medium for general sensor development has received significant attention and in particular some elegant luminescent supramolecular systems have been developed over the last 5 - 10 years for the detection of CWAs and their mimics. The majority of these have been solution based sensors (this limits the use in devices - solutions are inconvenient to store, often suffer from instability and sample preparation can be troublesome - see above), and with field based applications in mind, there is a need to move from solution responsive systems to surface immobilised receptor-reporter based sensors. This represents a significant gap in the field as luminescence sensing offers an attractive medium for immobilised sensors with potential to develop small portable devices from simple components. As such, we will use an alternative approach to overcome some of the above drawbacks. By utilising thin film (mono-layers) lanthanide based sensors where the sensor is deposited (immobilised) onto a surface (using the Langmuir-Blodgett technique) and undergoes a change in light emitting properties on exposure to low levels of CWA mimics we will overcome the limitations listed above. Throughout this research project we will explore this alternative approach for selectivity and sensitivity towards CWA mimics and ultimately assess its applicability for inclusion into functional devices. Therefore, our approach of combining the superior photophysical properties of the lanthanides, and the control over deposition afforded by the Langmuir-Blodgett technique will generate designer lanthanide luminescent sensors that can be immobilised easily and reliably, potentially transforming the field of on-surface molecular sensing.