Development of a cantilever sensor chip as a point-of-care (POC) device for label-free, rapid, and multiplexed detection of cancer protein biomarkers

疾病特异性蛋白质生物标志物的高通量鉴定和定量检测形成了许多诊断测试的基础，以指导临床医学的不同领域（例如癌症）的治疗。已经开发了各种蛋白质检测平台，以提供多分析物、特异性和灵敏性测定;其中酶联免疫吸附测定（ELISA）是金标准。虽然基于标记的技术被广泛用于信号转导的那些平台中，但标记掺入本身可能是高度异质的，并且标记过程是费力的、冗长的，并且显著增加了开发的成本和时间。因此，人们对开发用于生物分析的无标记技术非常感兴趣。基于微/纳米悬臂梁的传感器由于其将分子间的相互作用转化为力学的简单有效的传感机制而被认为是最有前途的无标记技术之一。通过利用分子相互作用（如抗原-抗体结合）改变固体表面上液体弯月面的接触角，我们可以证明微小的分子相互作用力转化为毛细作用力-一个更大的物理量。这一物理现象不仅可以作为一种新的无标记蛋白质检测机制，也可以作为一种实用的传感平台设计方法。我们以前已经证明了悬臂梁传感器的设计，利用这种传感机制的无标记蛋白质免疫测定与检测限低至1 pg/mL和10分钟内的短检测时间。在这个项目中，我们将进一步研究（i）有效的分子识别以及表面钝化的新的表面改性策略，（ii）新的悬臂梁设计和制造工艺，以提高信噪比和传感器的线性动态范围，以及（iii）集成微流体在单个传感器芯片上进行样品处理，用于癌症蛋白生物标志物的无标记，快速和多重检测。所提出的传感器芯片设计导致易于使用的免疫传感平台的构建，该平台旨在便于处理、最小的样品/试剂要求以及与多种生物标志物的兼容性。计划将来自癌症患者的生物样本应用于传感器芯片，以检测一组5种癌症蛋白质生物标志物，以提供一种护理点（POC）测试替代目前的生物标志物集中测试。

High-throughput identification and quantitative detection of disease-specific protein biomarkers forms the foundation of many diagnostic tests to direct therapy in diverse area of clinical medicine such as cancer. Various protein detection platforms have been developed to provide a multi-analytes, specific, and sensitive assay; among them the enzyme-linked immunosorbent assay (ELISA) is a golden standard. While the label-based techniques are widely utilized in those platforms for signal transduction, the label incorporation itself can be highly heterogeneous and the labeling procedure is laborious, lengthy, and adds significant cost and time for development. Therefore, there is great interest in developing label-free techniques for biological analysis. Micro/nano-cantilever-based sensors have been considered as one of the most promising label-free techniques because of the simple and efficient sensing mechanism by translating molecular interactions into mechanics. By utilizing a change in contact angle of a liquid meniscus on a solid surface through molecular interactions such as antigen-antibody binding, we could show that a tiny molecular interaction force is converted to a capillary force-a much larger physical quantity. This physical phenomenon could be served not only as a new mechanism for label-free protein detection but also as a practical method for a sensing platform design. We have previously demonstrated a cantilever sensor design by utilizing such a sensing mechanism for a label-free protein immunoassay with detection limit as low as 1 pg/mL and a short detection time within 10 minutes. In this project we will further investigate (i) new surface modification strategies for efficient molecular recognition as well as surface passivation, (ii) new cantilever design and fabrication process to improve the signal-to-noise ratio and linear dynamic range of sensor, and (iii) integrated microfluidics for sample processing on a single sensor chip for label-free, rapid, and multiplexed detection of cancer protein biomarkers. The proposed sensor chip design leads to the construction of an easy-to-use immunosensing platform intended for facile handling, minimal sample/reagent requirements and compatibility with diverse biomarkers. Biological samples from cancer patients are planned to be applied to the sensor chip to detect a panel of 5 cancer protein biomarkers, in an effort to provide a point-of-care (POC) test alternative to current centralized testing for biomarkers.