Wang Li, Liu Pengfei, Liu Zhijun, Zhao Kairen, Ye Shuying, Liang Guoxi, Zhu Jun-Jie
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
School of Pharmacy, Jiangsu University, Zhenjiang 212013, Jiangsu, China.
ACS Sens. 2020 Nov 25;5(11):3584-3590. doi: 10.1021/acssensors.0c01864. Epub 2020 Nov 10.
In contrast to common DNA walkers, multipedal DNA walkers exhibit larger walking area and faster walking kinetics and provide increased amplification efficiency. Consequently, they have received a considerable amount of attention in biosensing. However, most of them are synthesized by immobilizing multiple DNA walking strands on the surface of Au nanoparticles, which is tedious and time-consuming. Simple preparation of multipedal DNA walkers remains a challenge. Herein, we adopted a simple enzyme-free target-triggered catalytic hairpin assembly (CHA) circuit to synthesize a tripedal DNA walker. By walking on a DNA track-functionalized electrode, a sensitive electrochemiluminescence DNA nanomachine biosensor was constructed for sensing miRNA-21. The DNA walker was powered by toehold-mediated strand displacement; the whole process did not need the assistance of enzymes, thus avoiding tedious procedures and enzyme degradation under unfavorable environmental conditions. Specifically, a superior detection limit of 4 aM and a broad linear range of 10 aM to 1 pM were achieved. This CHA-tripedal DNA walker biosensor was then applied for the detection of miRNA-21 in human serum and showed high selectivity and excellent reproducibility, demonstrating its practical application in bioanalysis. In particular, the Y-shaped tripedal DNA walker comes from the DNA circuit, which makes the approach ideally suited for biosensing of small nucleic acid targets.
与普通的DNA步行器相比，多足DNA步行器具有更大的行走面积和更快的行走动力学，并提供更高的扩增效率。因此，它们在生物传感领域受到了广泛关注。然而，大多数多足DNA步行器是通过将多条DNA行走链固定在金纳米颗粒表面合成的，这一过程繁琐且耗时。简单制备多足DNA步行器仍然是一个挑战。在此，我们采用了一种简单的无酶靶标触发催化发夹组装（CHA）电路来合成一种三足DNA步行器。通过在DNA轨道功能化电极上行走，构建了一种灵敏的电化学发光DNA纳米机器生物传感器用于检测miRNA-21。该DNA步行器由链置换介导驱动；整个过程无需酶的辅助，从而避免了繁琐的程序以及在不利环境条件下酶的降解。具体而言，实现了4 aM的优异检测限和10 aM至1 pM的宽线性范围。然后将这种CHA-三足DNA步行器生物传感器应用于检测人血清中的miRNA-21，显示出高选择性和出色的重现性，证明了其在生物分析中的实际应用。特别是，Y形三足DNA步行器源自DNA电路，这使得该方法非常适合用于小核酸靶标的生物传感。
