Sepehri Sobhan, Eriksson Emil, Kalaboukhov Alexei, Zardán Gómez de la Torre Teresa, Kustanovich Kiryl, Jesorka Aldo, Schneiderman Justin F, Blomgren Jakob, Johansson Christer, Strømme Maria, Winkler Dag
Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, Göteborg 412 96, Sweden.
RISE Acreo AB, SE-411 33 Göteborg, Sweden.
APL Bioeng. 2017 Dec 29;2(1):016102. doi: 10.1063/1.4999713. eCollection 2018 Mar.
A bioassay based on a high- superconducting quantum interference device (SQUID) reading out functionalized magnetic nanoparticles (fMNPs) in a prototype microfluidic platform is presented. The target molecule recognition is based on volume amplification using padlock-probe-ligation followed by rolling circle amplification (RCA). The MNPs are functionalized with single-stranded oligonucleotides, which give a specific binding of the MNPs to the large RCA coil product, resulting in a large change in the amplitude of the imaginary part of the ac magnetic susceptibility. The RCA products from amplification of synthetic target DNA were investigated using our SQUID ac susceptibility system in microfluidic channel with an equivalent sample volume of 3 l. From extrapolation of the linear dependence of the SQUID signal versus concentration of the RCA coils, it is found that the projected limit of detection for our system is about 1.0 × 10 RCA coils (0.2 × 10 mol), which is equivalent to 66 fM in the 3 l sample volume. This ultra-high magnetic sensitivity and integration with microfluidic sample handling are critical steps towards magnetic bioassays for rapid detection of DNA and RNA targets at the point of care.
本文介绍了一种基于超导量子干涉装置（SQUID）的生物检测方法，该方法用于在原型微流控平台中读取功能化磁性纳米颗粒（fMNP）。目标分子的识别基于使用锁式探针连接的体积放大，随后进行滚环扩增（RCA）。磁性纳米颗粒用单链寡核苷酸进行功能化，这使得磁性纳米颗粒与大型RCA线圈产物发生特异性结合，从而导致交流磁化率虚部幅度发生较大变化。使用我们的SQUID交流磁化率系统，在等效样品体积为3μl的微流控通道中研究了合成目标DNA扩增产生的RCA产物。从SQUID信号与RCA线圈浓度的线性关系外推可知，我们系统的预计检测限约为1.0×10个RCA线圈（0.2×10摩尔），这相当于3μl样品体积中的66fM。这种超高的磁灵敏度以及与微流控样品处理的集成是迈向用于在护理点快速检测DNA和RNA靶标的磁性生物检测的关键步骤。
