Laser-engineered nanocomposites for sensing applications

表面增强拉曼散射(SERS)是一种非常强大的光学检测平台，可以开发出适合实时监测的灵敏和定量的分析方法。这项技术提供了有关靠近等离子体纳米结构的分子的振动“指纹”的信息，因此允许对检测到的分析物类型进行唯一分类。该方法也已被证明具有单分子检测能力。基于SERS的方法已经在生物分析传感中实现了一些重要的应用，如体内肿瘤靶向、临床相关浓度的葡萄糖传感和微生物系统分析，并被认为是纳米生物技术和个性化医学等领域取得进展的主要先决条件。尽管表面增强拉曼光谱比常用的基于荧光的方法有明显的优势，但SERS仍未被确立为一种分析工具。这在一定程度上是由于SERS底物的微小变化(制备、聚集、表面形态等)。对SERS表现有很大的影响。因此，必须解决SERS活性衬底的稳定性和重现性问题，以促进其在定量分析中的应用。目前，具有中到高增强因子、可重复性和一致性响应的SERS衬底制备技术主要有电子束光刻、纳米压印、自组装纳米球、混合纳米孔光刻方法等。这些技术对于大面积SERS衬底的生产仍然昂贵且相当繁琐，因此商业化的SERS平台价格较高。该项目的重点是展示基于激光工程纳米复合材料系统的新型SERS平台，以显著改善性能和制造控制，解决当前SERS材料的限制。不同掺杂浓度和体积填充因子的Ag/Au离子和Ag-/Au纳米颗粒掺杂衬底可用于SERS分析，常用的激发波长在400~1000 nm范围内。为了实现几何形状可控、增强因子可重现的大面积平面平台，将开发一种空间选择性纳米复合退火技术，以实现用于定量SERS分析的稳健传感平台的阶跃变化。此外，拟议的材料系统将构成未来用于生物医学、环境和安全应用的微流控传感设备的构建块。

Surface-Enhanced Raman Scattering (SERS) is an extremely powerful optical detection platform for the development of sensitive and quantitative analytical methods suitable for real-time monitoring. This technique provides information about the vibronic 'fingerprint' of a molecule located close to plasmonic nanostructures and therefore allows for a unique classification of the type of analyte detected. This method has also been proven to have a single-molecule detection capability. SERS-based approaches have enabled a number of important applications in bioanalytical sensing, such as in vivo tumour targeting, glucose sensing at clinically relevant concentrations and microbial system analysis, and are considered a major prerequisite for progress in areas such as nanobiotechnology and personalised medicine. In spite of the apparent advantages over commonly used fluorescence-based methods, SERS is yet to be established as an analytical tool. This is, in part, due to the fact that small variations in the SERS substrate (preparation, aggregation, surface morphology, etc.) have drastic effects on the SERS performance. Therefore the stability and reproducibility issues of SERS-active substrates have to be addressed in order to facilitate its application in quantitative analysis.Current fabrication techniques of SERS substrates with moderate to high enhancement factors, and reproducible and uniform responses are dominated by e-beam lithography, nano-imprint, self-assembled nanosphere, hybrid nanoporous lithography methods, etc. These techniques are still costly and rather cumbersome for production of large area SERS substrates, hence the high price of commercially available SERS platforms. The focus of this project is to demonstrate novel SERS platforms based on laser-engineered nanocomposite systems for dramatically improved performance and fabrication control, addressing current SERS materials limitations. Tailored Ag-/Au-ion and Ag-/Au-nanoparticle doped substrates with different dopant concentrations and volume filling factors will be fabricated suitable for SERS analysis with frequently used excitation wavelengths in the spectral region from 400 to 1000 nm. A spatially selective nanocomposite annealing technique will be developed in order to realise large area planar platforms with controllable geometry and reproducible enhancement factors, allowing a step change in fabrication of robust sensing platforms for quantitative SERS analysis. Furthermore, the proposed material systems will form the building blocks of a future microfluidic sensing devices for biomedical, environmental and security applicatons.