U-bent fiber optic plasmonic biosensor platform for ultrasensitive analyte detection

• Published in: Sensors and actuators. B, Chemical Vol. 321; p. 128463
• Main Authors: Bandaru, Ramakrishna, Divagar, M, Khanna, Shruti, Danny, Christina Grace, Gupta, Shalini, Janakiraman, Vani, V V R, Sai
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.10.2020; Elsevier Science Ltd
• Subjects: Absorbance; Attomolar analyte detection; Biosensors; Dipping; Evanescent wave absorbance; Evanescent waves; Fiber optic biosensor; Fiber optics; Gold nanoparticles; IgG antibody; Immunoassay; Labels; Light emitting diodes; Low cost; Luminous intensity; Nanoparticles; Optical fibers; Plasmonic labels; Plasmonics; Evanescent wave absorbance; Plasmonic labels; Gold nanoparticles; Attomolar analyte detection; Fiber optic biosensor
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2020.128463

[Display omitted] This study demonstrates a rapid, wash-free, dip-type plasmonic fiberoptic absorbance biosensor (P-FAB) capable of zeptomole analyte detection and 6-orders of wide dynamic range. It involves a sandwich immunoassay on a compact U-bent fiber optic probe surface that works by dipping an antibody-functionalized probe into a mixture of sample and gold nanoparticle (AuNP) label suspension. The U-bent fiberoptic probes with a high evanescent wave absorbance sensitivity allow detection of the high extinction AuNP labels measured in terms of light intensity change using a pair of LED and photodetector (PD). This simple and low-cost P-FAB gives an unprecedented detection limit of 0.17 zeptomole for human immunoglobulin G (HIgG) in 25 μL buffer in just 25 min. Further silver enhancement of AuNP labels for 5 min results in a limit of quantitation (LoQ) down to 0.17 zeptomole (∼100−150 molecules in 25 μL), making P-FAB a highly sensitive and low-cost technology for point-of-care diagnostics.