Division of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA.
Biosens Bioelectron. 2011 Feb 15;26(6):2927-33. doi: 10.1016/j.bios.2010.11.039. Epub 2010 Dec 3.
A microfluidic biosensor chip with an embedded three-electrode configuration is developed for the study of the voltammetric response of a nanoelectrode array with controlled inter-electrode distance in a nanoliter-scale sample volume. The on-chip three-electrode cell consists of a 5 × 5 array of Au working nanoelectrodes with radii between 60 and 120 nm, a Cl(2)-plasma-treated Ag/AgCl reference electrode, and a Au counter electrode. The nanoelectrode array is fabricated by creating high-aspect-ratio pores through an alumina insulating layer using an I(2) gas-assisted focused-ion-beam (FIB) milling, ion beam sculpting, and electrodeposition of Au. The glass substrate with the electrode pattern is assembled with a polydimethylsiloxane (PDMS) microchannel slab giving a volume of 180 nL for each channel. Cyclic voltammetry calibration with a standard redox species exhibits a significant increase of current density by two orders of magnitude compared to that obtained from a microelectrode. On-chip functionalization of the nanoelectrodes with a prostate-specific antigen (PSA) biosensor complex and detection of PSA based on a competitive immunoassay method are performed. The detection limit is approximately 10 pg/mL (∼270 fM), which corresponds to roughly 30,000 copies of PSA in the microchannel test volume.
一种带有嵌入式三电极结构的微流控生物传感器芯片被开发出来，用于研究在纳升级样品体积中具有可控电极间距离的纳米电极阵列的伏安响应。片上三电极池由 5×5 个 Au 工作纳米电极阵列组成，电极半径在 60 到 120nm 之间，一个 Cl(2)-等离子体处理的 Ag/AgCl 参比电极，以及一个 Au 对电极。纳米电极阵列是通过使用 I(2)气体辅助聚焦离子束（FIB）铣削、离子束雕刻和 Au 电沉积在氧化铝绝缘层中创建高纵横比孔来制造的。带有电极图案的玻璃基底与聚二甲基硅氧烷（PDMS）微通道板组装在一起，每个通道的体积为 180nL。用标准氧化还原物质进行的循环伏安校准表明，与从微电极获得的电流密度相比，电流密度显著增加了两个数量级。在纳米电极上进行基于前列腺特异性抗原（PSA）生物传感器复合物的片上功能化，并基于竞争免疫测定法检测 PSA。检测限约为 10pg/mL（约 270fM），这对应于微通道测试体积中大约 30,000 个 PSA 拷贝。
