Toward Point-of-Care Drug Testing: A New Paradigm for On-Chip Chromatography Coupled with Surface-Enhanced Raman Scattering

面向床旁药物检测：芯片上色谱耦合的新范式 表面增强拉曼散射 项目摘要 原则上，表面增强拉曼光谱（Sers）可以提供对目标的唯一识别 分析物，特别是小分子，如非法药物。然而，在实践中，对于真实的来说，这并不总是正确的- 由于各种形式的干扰，例如来自大生物分子的非特异性结合， （蛋白质、DNA等）在复杂的生物样品的金属纳米颗粒（NP）的表面。因此，我们认为， 选择性的（例如，测定）或分离（例如，需要具有一定特异性的色谱）过程来 将现有的Sers技术从实验室分析工具转化为临床应用。一个迫切需要这样的- 芯片传感技术是床旁（POC）药物测试由于药物滥用的惊人蔓延，助长了 通过生产廉价的，易于制造的药物变体。现有的测试方法，包括气体 色谱-质谱法（GC/MS）和高效液相色谱法（HPLC）， 需要繁琐的样品制备，昂贵的试剂和大量的操作员专业知识， 适用于临床和执法环境的POC测试。 硅藻土，也被称为硅藻土，由硅藻的化石组成，是一种硬壳的 藻类作为一种来源于地质矿床的资源丰富、性价比高的天然光子生物硅， 各种独特的性能，包括高度多孔的微米和纳米结构，优异的吸附能力， 丰富的表面化学和独特的微流体特性。这个R21项目的目标是开发一个 新的芯片上色谱技术与使用硅藻土薄膜的Sers传感相结合， 其可以提供便携的、具有成本效益的解决方案来检测复杂生物流体中的各种非法药物 样品特别是在这个项目中，我们将把这种芯片实验室技术应用于可卡因的POC测试， 大麻简而言之，我们将旋涂超薄（最终降至约5μm的单层）硅藻土 在常规玻璃基板上，并通过原位合成集成高密度等离子体纳米颗粒。这种混合 光子等离子体纳米结构薄膜将同时用作薄层色谱（TLC）， 将药物分子从复杂的生物流体和超灵敏的Sers基底中分离出来， 拉曼峰。通过与市售便携式拉曼光谱仪的结合， TLC-SERS技术将使快速，多重POC传感具有高特异性。较 现有的基于硅胶板的TLC-SERS方法，我们希望我们的技术能够实现>100倍的增强 灵敏度（低至<1 ppm），由于光子晶体效应从硅藻硅藻细胞壳和超小 多尺度多孔结构的厚度。最后但并非最不重要的是，广泛的可用性和低成本 （<1美元/芯片）的多功能TLC-SERS基底非常适合用于可卡因的POC药物测试， 大麻和其他非法药物的尿液，唾液和血液。我们必须指出，这种TLC-SERS传感器 可以很容易地应用于许多其他应用的无标签传感，例如食品安全、水质 监测和过敏性生物标志物检测。

Toward Point-of-Care Drug Testing: A New Paradigm for On-Chip Chromatography Coupled with Surface-Enhanced Raman Scattering PROJECT SUMMARY In principle, surface enhanced Raman spectroscopy (SERS) can provide unique identification to a target analyte, especially small molecules such as illicit drugs. In practice, however, this is not always true for real- world samples due to various forms of interference such as nonspecific binding from large biomolecules (proteins, DNAs, etc.) in complex biological samples to the surface of metallic nanoparticles (NPs). Therefore, a selective (e.g., assay) or separation (e.g., chromatography) process with certain specificity is needed to transform existing SERS technique from a lab analysis tool into clinical usage. One urgent need for such on- chip sensing technology is point-of-care (POC) drug testing due to the alarming spread in drug abuse, fuelled by the production of inexpensive, easy-to-manufacture drug variants. Existing testing methods, including gas chromatography with mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC), demand tedious sample preparation with expensive reagents and substantive operator expertise, and are ill- suited to clinical and law enforcement settings for POC testing. Diatomaceous earth, also known as diatomite, consists of fossilized remains of diatoms, a type of hard-shelled algae. As a type of abundant and cost-effective natural photonic biosilica from geological deposits, it has a variety of unique properties including highly porous micro- and nano-structures, excellent adsorption capacity, rich surface chemistry, and unique micro-fluidic properties. The objective of this R21 project is to develop a new on-chip chromatography technology coupled with SERS sensing using diatomaceous earth thin film, which can provide a portable, cost-effective solution to detect various illicit drugs in complex biological fluidic samples. Particularly in this project, we will apply this lab-on-chip technology for POC testing of cocaine and Marijuana. Briefly, we will spin coat ultra-thin (eventually down to monolayer around 5μm) diatomaceous earth on regular glass substrates, and integrate high-density plasmonic NPs through in-situ synthesis. This hybrid photonic-plasmonic nanostructured thin film will act simultaneously as a thin layer chromatography (TLC) to separate drug molecules from the complex biofluid and ultra-sensitive SERS substrates to probe the signature Raman peaks. Through the combination with commercially available portable Raman spectrometers, our diatomite TLC-SERS technology will enable rapid, multiplex POC sensing with high specificity. Compared with existing TLC-SERS methods based on silica gel plates, we expect our technology to achieve >100× enhanced sensitivity (down to <1ppm) due to the photonic crystal effect from diatom frustules and the ultra-small thickness of the multi-scale porous structure. Last but not the least, the wide availability and low cost (<$1/chip) of the multifunctional TLC-SERS substrates are perfectly suitable for POC drug testing of cocaine, marijuana, and other illicit drugs from urine, saliva and blood. We must point out that such TLC-SERS sensors can be readily applied for label-free sensing for many other applications such as food safety, water quality monitoring, and allergic biomarker detection.