Abstract：
Successful construction of a detection method for Salmonella typhimurium (S. typhimurium) based on the synergy of hybridization chain reaction (HCR) and fluorescence was realized in this paper. First, the aptamer modified with the quenching group Black Hole Quencher-1 acid (BHQ1) was immobilized on the magnetic beads in combination with the complementary chain of the aptamer modified with 6-carboxyfluorescein (6-FAM). Second, S. typhimurium and cDNA-6-FAM immobilized on magnetic beads competitively bound to the aptamer. Finally, the cDNA-6-FAM was released after magnetic separation acted as a promoter to trigger HCR amplification when the target presented. The fluorescence signal could be significantly improved by the combination of green SYBR Green I (SGI) and HCR long double-stranded DNA and the fluorescent synergy of 6-FAM and SGI. Because of the separation of target and its aptamer, the trigger strand was abstracted by magnetic separation. There was no HCR to generate long double-stranded DNA, and the fluorescence of excess hairpin/SGI could be adsorbed through UIO66 so that only a very low background signal was detected. This fluorescent sensor was capable of monitoring S. typhimurium in the range of 10-3.2 × 107 CFU mL-1 with a limit of detection as low as 1.5 CFU mL-1. Because of the excellent properties of the aptasensor and the validity of SGI fluorescence synergy, this HCR enzyme-free amplification strategy could be generalized to other areas.
摘要：
鼠伤寒沙门氏菌(S.本文实现了基于杂交链反应（HCR）和荧光的协同作用。首先,用猝灭基团黑洞猝灭-1酸(BHQ1)修饰的适体与用6-羧基荧光素(6-FAM)修饰的适体的互补链结合固定在磁珠上。第二,鼠伤寒沙门氏菌和固定在磁珠上的cDNA-6-FAM竞争性结合到适体。最后,当靶标出现时,磁性分离后,cDNA-6-FAM作为启动子被释放以触发HCR扩增.绿色SYBRGreenI(SGI)和HCR长双链DNA的组合以及6-FAM和SGI的荧光协同作用可以显著改善荧光信号。由于靶标及其适体的分离，通过磁分离提取触发链。没有产生长双链DNA的HCR,并且过量发夹/SGI的荧光可以通过UIO66吸附，因此仅检测到非常低的背景信号。该荧光传感器能够监测10-3.2×107CFUmL-1范围内的鼠伤寒沙门氏菌，检出限低至1.5CFUmL-1。由于aptasensor的优异性能和SGI荧光协同作用的有效性，这种HCR无酶扩增策略可以推广到其他领域。
