Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA.
Department of Computer Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA.
Biosens Bioelectron. 2022 Mar 15;200:113918. doi: 10.1016/j.bios.2021.113918. Epub 2021 Dec 25.
Novel methods that enable facile, ultrasensitive and multiplexed detection of low molecular weight organic compounds such as metabolites, drugs, additives, and organic pollutants are valuable in biomedical research, clinical diagnosis, food safety and environmental monitoring. Here, we demonstrate a simple, rapid, and ultrasensitive method for detection and quantification of small molecules by implementing a competitive immunoassay with an ultrabright fluorescent nanolabel, plasmonic fluor. Plasmonic-fluor is comprised of a polymer-coated gold nanorod and bovine serum albumin conjugated with molecular fluorophores and biotin. The synthesis steps and fluorescence emission of plasmonic-fluor was characterized by UV-vis spectroscopy, transmission electron microscopy, and fluorescence microscopy. Plasmon-enhanced competitive assay can be completed within 20 min and exhibited more than 30-fold lower limit-of-detection for cortisol compared to conventional competitive ELISA. The plasmon-enhanced competitive immunoassay when implemented as partition-free digital assay enabled further improvement in sensitivity. Further, spatially multiplexed plasmon-enhanced competitive assay enabled the simultaneous detection of two analytes (cortisol and fluorescein). This simple, rapid, and ultrasensitive method can be broadly employed for multiplexed detection of various small molecules in research, in-field and clinical settings.
新型方法能够实现对低分子量有机化合物（如代谢物、药物、添加剂和有机污染物）的简便、超灵敏和多重检测，在生物医学研究、临床诊断、食品安全和环境监测中具有重要价值。在这里，我们展示了一种通过使用超亮荧光纳米标签——等离子体荧光来实现小分子检测和定量的简单、快速和超灵敏方法。等离子体荧光由聚合物包覆的金纳米棒和与荧光团和生物素缀合的牛血清白蛋白组成。等离子体荧光的合成步骤和荧光发射通过紫外可见光谱、透射电子显微镜和荧光显微镜进行了表征。等离子体增强竞争测定可以在 20 分钟内完成，与传统的竞争 ELISA 相比，皮质醇的检测限低 30 多倍。当作为无分区数字测定实施时，等离子体增强竞争免疫测定进一步提高了灵敏度。此外，空间多重化的等离子体增强竞争测定能够同时检测两种分析物（皮质醇和荧光素）。这种简单、快速和超灵敏的方法可以广泛应用于研究、现场和临床环境中各种小分子的多重检测。
