Ultralow-limit of detection optical fiber LSPR biosensor based on a ring laser for des- <i>γ</i> -carboxy prothrombin detection
Xiangshan Li, Ragini Singh, Bingyuan Zhang, Santosh Kumar, Guoru Li
Abstract
The ultralow limit of detection (LoD) and exceptional sensitivity of biosensors are a significant challenge currently faced in the field. To address this challenge, this work proposes a highly sensitive laser ring cavity biosensor capable of detecting low concentrations of des- γ -carboxy prothrombin (DCP). A tapered W-shaped fiber probe based on multi-mode fiber (MMF)-multi-core fiber (MCF)-MMF is developed to excite strong evanescent waves (EWs). By immobilizing gold nanorods (GNRs) on the fiber probe, localized surface plasmon resonance (LSPR) is generated at the near infrared wavelength to further enhance the sensitivity of the fiber probe. Moreover, an erbium-doped fiber (EDF) ring laser with a narrow full width at half maximum (FWHM) of 0.11 nm is employed as a light source. The spectrum with narrow FWHM has been demonstrated to obtain lower LoD. Compared to the ASE light source, the LoD of the laser ring cavity can be reduced by an order of magnitude. The developed biosensor is capable of detecting DCP within a concentration range of 0–1000 ng/mL, and the detection sensitivity of 0.265 nm/lg(ng/mL) and the LoD of 367.6 pg/mL are obtained. In addition, the proposed laser ring cavity biosensor demonstrates good specificity, reproducibility, and repeatability by corresponding tests. The study results indicate that the proposed biosensor has potential in the detection of hepatocellular carcinoma markers.