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Wang Z, Zhou Q, Seth A, Kolla S, Luan J, Jiang Q, Rathi P, Gupta P, Morrissey JJ, Naik RR, Singamaneni S. Plasmonically-enhanced competitive assay for ultrasensitive and multiplexed detection of small molecules. Biosens Bioelectron 2022; 200:113918. [PMID: 34990957 PMCID: PMC8852303 DOI: 10.1016/j.bios.2021.113918] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 12/12/2021] [Accepted: 12/22/2021] [Indexed: 01/13/2023]
Abstract
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.
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Affiliation(s)
- Zheyu Wang
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA
| | - Qingjun Zhou
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA
| | - Anushree Seth
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA
| | - Samhitha Kolla
- Department of Computer Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA
| | - Jingyi Luan
- Auragent Bioscience LLC, St. Louis, MO, 63108, USA
| | | | - Priya Rathi
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA
| | - Prashant Gupta
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA
| | - Jeremiah J Morrissey
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, 63110, USA; Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Rajesh R Naik
- 711 Human Performance Wing, Air Force Research Laboratory, Wright Patterson Air Force Base, Dayton, OH, 45433, USA.
| | - Srikanth Singamaneni
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St Louis, MO, 63130, USA; Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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