Tzouvadaki I, Madaboosi N, Taurino I, Chu V, Conde J P, De Micheli G, Carrara S
Integrated System Laboratory EPFL, Lausanne, Switzerland.
J Mater Chem B. 2016 Mar 28;4(12):2153-2162. doi: 10.1039/c6tb00222f. Epub 2016 Mar 3.
Semiconductor nanowires are emerging as promising building blocks for biosensors enabling direct electrical detection of various biomolecules. In this framework, two-terminal Schottky-barrier silicon (Si) nanowire arrays that exhibit memristive electrical response, so-called memristive devices, are bio-functionalized and converted to memristive biosensors for bio-detection purposes. A comparative analysis of three bio-functionalization strategies is proposed here in order to design and develop optimum memristive biosensors to be implemented in label-free sensing applications. The surface of the device is modified with an anti-free-Prostate Specific Antigen (PSA) antibody as the case of study via: (a) direct adsorption on the device surface, (b) a bio-affinity approach using biotin-streptavidin combination and (c) covalent attachment using (3-glycidyloxypropyl)trimethoxysilane (GPTES). The optimum memristive biosensor is defined via the calibration and comparative study of the biosensors' electrical response under controlled environmental conditions (humidity and temperature) in order to maximize the performance of the biosensor. In addition, it is demonstrated that the direct passive adsorption strategy presents double the performance of the other two methods. The uptake of biological molecules on the nanostructure surface is verified by atomic force microscopy and confocal microscopy. Scanning electron microscopy reveals the details of the surface morphology of the nanofabricated structures before and after bio-functionalization for the three methods applied. The system shows potential for general application in molecular diagnostics, and, in particular, for the early detection of prostate cancer.
半导体纳米线正成为生物传感器的理想构建模块，能够对各种生物分子进行直接电检测。在此框架下，具有忆阻电响应的两端肖特基势垒硅（Si）纳米线阵列，即所谓的忆阻器件，被进行生物功能化，并转化为用于生物检测目的的忆阻生物传感器。本文提出了三种生物功能化策略的比较分析，以便设计和开发用于无标记传感应用的最佳忆阻生物传感器。以抗游离前列腺特异性抗原（PSA）抗体为例，通过以下方式对器件表面进行修饰：（a）直接吸附在器件表面；（b）使用生物素 - 链霉亲和素组合的生物亲和方法；（c）使用（3 - 缩水甘油氧基丙基）三甲氧基硅烷（GPTES）进行共价连接。通过在受控环境条件（湿度和温度）下对生物传感器的电响应进行校准和比较研究，以确定最佳忆阻生物传感器，从而最大化生物传感器的性能。此外，结果表明直接被动吸附策略的性能是其他两种方法的两倍。通过原子力显微镜和共聚焦显微镜验证了生物分子在纳米结构表面的摄取情况。扫描电子显微镜揭示了应用三种方法进行生物功能化前后纳米制造结构表面形态的细节。该系统在分子诊断中具有广泛应用潜力，特别是在前列腺癌的早期检测方面。
