Localized Surface Plasmon Resonance based Hetero-core Optical Fiber Sensor Structure for the Detection of L-Cysteine

• Published in: IEEE transactions on nanotechnology Vol. 19; p. 1
• Main Authors: Singh, Lokendra, Singh, Ragini, Zhang, Bingyuan, Kaushik, Brajesh Kumar, Kumar, Santosh
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Atomic force microscopy; Binding sites; Biocompatibility; Cysteine; Electron microscopy; etero-core; Evanescent waves; Gold; gold nanoparticles; Graphene; graphene oxide; L-Cysteine; Microscopy; Nanoparticles; optical fiber; Optical fiber communication; Optical fiber dispersion; Optical fiber sensors; Optical fibers; Optical surface waves; Polyvinyl alcohol; polyvinyl alcohol-silver nanoparticles; Probes; Sensors; Silver; Spectrophotometry; Splicing; Stability analysis; Surface plasmon resonance; Synthesis
• ISSN: 1536-125X; 1941-0085
• DOI: 10.1109/TNANO.2020.2975297

In this work, a hetero-core optical fiber sensor structure is developed for the diagnosis of L-Cysteine content in human urine. The hetero-core structure is created by sequentially cascading the single mode-multimode-single mode fibers using thermal fusion splicing. The multimode section of fiber probe is etched out and coated with synthesized gold nanoparticles (AuNPs), polyvinyl alcohol stabilized silver nanoparticles (PVA-AgNPs) and graphene oxide (GO). The AuNPs and PVA-AgNPs are used to initiate the localized surface plasmon resonance (LSPR) phenomenon on the application of exponentially decaying evanescent waves. The layer of GO is used to provide the larger surface area and binding sites for the L-Cysteine (L-Cys) molecules. Based on the combination of NPs, two different configurations of sensor probes are developed. In first one, a layer of AuNPs is deposited over fiber surface and further followed by the coating of GO, and named Probe I. In the second one, a layer of PVA-AgNPs is sandwiched between the fiber surface and GO layer and termed as Probe II. The characterization of synthesized NPs and GO solutions, and developed sensor probes are done by using UV-Vis spectrophotometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). To authenticate the biocompatibility of developed sensor probes, the artificial aqueous samples of L-Cys ranges from 0 μM to 1 mM are tested. To determine the stability of L-Cys, a pH level based study is also carried out to ensure the good stability of analyte in aqueous samples. From the results, it was ascertained that the response of Probe II is better in terms of attained limit of detection and sensitivity that is 126.6 μM and 0.0009 nm/μM, respectively.