Department of Mechanical and Biomedical Engineering, ‡Department of Biology and Chemistry, §School of Creative Media, and ∥Centre for Robotics and Automation, City University of Hong Kong , Hong Kong Special Administrative Region, China.
ACS Appl Mater Interfaces. 2015 Oct 21;7(41):22821-30. doi: 10.1021/acsami.5b05018. Epub 2015 Oct 8.
Visual detection of nucleic acids provides simple and rapid screening for infectious diseases or environmental pathogens. However, sensitivity is the current bottleneck, which may require enzymatic amplification for targets in low abundance and make them incompatible with detection at resource-limited sites. Here we report an enzyme-free amplification that provides a sensitive visual detection of ssDNA/RNA oligonucleotides on the basis of nano "sticky balls". When target oligonucleotides are present, magnetic microparticles (MMPs) and gold nanoparticles (AuNPs) were linked together, allowing the collection of AuNPs after magnetic attraction. Subsequently, the collected AuNPs, which carry many oligonucleotides, were used as the sticky balls to link a second pair of MMPs and polymer microparticles (PMPs). Thus, because the magnetic field can attract the MMPs as well as the linked PMPs to the sidewall, the reduction of suspended PMPs yields a change of light transmission visible by the naked eye. Our results demonstrate that the limit of detection is 10 amol for ssDNAs (228 fM in 45 μL) and 75 amol for ssRNAs (1.67 pM in 45 μL). This method is also compatible with the serum environment and detection of a microRNA, miR-155, derived from human breast cancer cells. With significantly improved sensitivity for visual detection, it provides great potential for point-of-care applications at resource-limited sites.
基于纳米“粘性球”的无酶扩增可实现 ssDNA/RNA 寡核苷酸的灵敏可视化检测。当存在靶标寡核苷酸时，磁性微球 (MMPs) 和金纳米颗粒 (AuNPs) 连接在一起，通过磁吸引收集 AuNPs。随后，收集的 AuNPs 携带许多寡核苷酸，可作为粘性球连接第二对 MMP 和聚合物微球 (PMP)。因此，由于磁场可以吸引 MMP 以及连接的 PMP 到侧壁，悬浮的 PMP 的减少会导致光传输的变化，肉眼可见。我们的结果表明，ssDNAs 的检测限为 10 amol（45 μL 中 228 fM），ssRNAs 的检测限为 75 amol（45 μL 中 1.67 pM）。该方法还与血清环境兼容，可检测源自人乳腺癌细胞的 microRNA，miR-155。这种方法显著提高了可视化检测的灵敏度，为在资源有限的场所进行即时护理应用提供了巨大潜力。
