Goyal Garima, Ammanath Gopal, Palaniappan Alagappan, Liedberg Bo
Interdisciplinary Graduate School, Nanyang Technological University, Singapore 639798.
Center for Biomimetic Sensor Science, Nanyang Technological University, Singapore 637553.
ACS Sens. 2020 Aug 28;5(8):2476-2485. doi: 10.1021/acssensors.0c00667. Epub 2020 Aug 6.
Standard detection methods for nucleic acids, an important class of diagnostic biomarkers, are often laborious and cumbersome. In need for development of facile methodologies, localized surface plasmon resonance (LSPR) assays have been widely explored for both spectroscopic and visual detection of nucleic acids. Our sensing approach is based on monitoring changes in the LSPR band due to interaction between peptide nucleic acid (PNA) and plasmonic nanoparticles (NPs) in the presence/absence of target nucleic acid. We have investigated the importance of tuning the stoichiometry of PNA to NPs to enable "naked-eye" detection of nucleic acids at clinically relevant concentration ranges. Assaying in plasma is achieved by incorporation of silver in gold NPs (AuNPs) via an alloying process. The synthesized gold/silver alloy NPs reduce nonspecific adsorption of proteinaceous interferents in plasma. Furthermore, the gold/silver alloy NPs absorb in the most sensitive cyan to green transition zone (∼500 nm) yielding highly competitive visual limits of detection (LODs). The visual LOD (calculated objectively using the Δ algorithm) for a model microRNA (mir21) using a productive combination of stoichiometric tuning of the PNA to NP ratio and compositional tuning of the NPs in buffer and plasma extract equals 200 pM (∼250 times lower than existing reports) and 3 nM, respectively. We envision that the proposed LSPR assay based on AuAgNPs offers an avenue for rapid and sensitive on-site detection of nucleic acids in complex matrixes in combination with efficient target extraction kits.
核酸作为一类重要的诊断生物标志物，其标准检测方法往往繁琐费力。由于需要开发简便的方法，局部表面等离子体共振（LSPR）分析已被广泛用于核酸的光谱检测和可视化检测。我们的传感方法基于监测在有/无靶核酸存在的情况下，肽核酸（PNA）与等离子体纳米颗粒（NPs）之间相互作用导致的LSPR带的变化。我们研究了调整PNA与NPs化学计量比的重要性，以实现临床相关浓度范围内核酸的“裸眼”检测。通过合金化过程将银掺入金纳米颗粒（AuNPs）中来实现在血浆中的检测。合成的金/银合金纳米颗粒减少了血浆中蛋白质干扰物的非特异性吸附。此外，金/银合金纳米颗粒在最敏感的青色到绿色过渡区（约500nm）吸收，产生极具竞争力的可视化检测限（LOD）。在缓冲液和血浆提取物中，通过对PNA与NP比例进行化学计量调整以及对NPs进行成分调整的有效组合，对模型微小RNA（mir21）的可视化LOD（使用Δ算法客观计算）分别为200pM（比现有报告低约250倍）和3nM。我们设想，基于AuAgNPs提出的LSPR分析方法结合高效的靶标提取试剂盒，为在复杂基质中快速、灵敏地现场检测核酸提供了一条途径。
