Yu Wang

The development of a p-cresol biosensor for aquaculture, marine life, and healthcare applications is described in this study. The biosensor is based on localized surface plasmon resonance (LSPR) and employs a novel tapered-in-tapered fiber (TiTF) probe. Gold nanoparticles (AuNPs) and copper oxide nanoflowers (CuO-NFs) on TiTF structures are immobilized on this probe. The developed probe’s performance was evaluated by measuring the response to a variety of p-cresol solution concentrations. Combining AuNPs and CuO-NFs improves the sensitivity and anti-interference capability of the sensing probe. When the p-cresol solution reacts with the tyrosinase enzyme, the refractive index on the sensing region of the probe changes, and the resulting spectrum varies. The linear range, the limit of detection (LoD), and sensitivity of the proposed sensor are 0–1 mM, 0.14 mM, and 3.8 pm/mM, respectively. The probe is subjected to extensive testing, including LoD, repeatability, reusability, stability, selectivity, and pH testing, that all obtain satisfactory results.

The article describes the development of a hetro-core optical fiber sensor structure based on localized surface plasmon resonance (LSPR) for the detection of cardiac troponin I (cTnI) solution. This was accomplished by fabricating a single-mode fiber - multimode fiber - single-mode fiber (SMS) structure. Then, fiber structure is immobilized with gold nanoparticles (AuNPs) and cerium oxide nanoparticles (CeO₂-NPs) to improve its sensing capabilities. An UV-Vis spectrophotometer and a high-resolution transmission electron microscope (HR-TEM) are used to determine the morphology of synthesized nanoparticles. Scanning electron microscopy (SEM) is used to examine the state of immobilized NPs on the surface of sensing region. The developed sensor probe has a linear range of 0 to 1000 ng/mL cTnI, a sensitivity of 3 pm/(ng/mL), and a limit of detection (LoD) of 108.15 ng/mL. In real time, the proposed sensor will be used in a practice to detect acute myocardial infarction (AMI).

This study used localized surface plasmon resonance (LSPR) technology to develop an optical fiber biosensor for the detection of cardiac troponin I (cTnI). The etched core mismatch, multimode–photosensitive–multimode (MPM) fiber structure, is used in this study. Following that, graphene oxide (GO), gold nanoparticles (AuNPs), and molybdenum disulfide nanoparticles (MoS ₂ -NPs) are immobilized to the etched MPM surface to improve the sensitivity and stability of the sensor probe. Furthermore, the sensing surface is functionalized with an enzyme to improve the selectivity performance. The absorption spectrum of nanomaterials is determined using a UV-Vis spectrophotometer and a transmission electron microscope (TEM), while the surface of an immobilized probe was observed using a scanning electron microscope (SEM). To determine the sensor’s reliability, a variety of experiments are carried out, including sensing, reusability, reproducibility, stability, pH, and selectivity. Sensitivity of 3.4 pm/(ng/mL), a correlation coefficient of 0.928, limit of detection (LoD) of 96.2638 ng/mL, and linear range of 0–1000 ng/mL are among the sensor’s final performance specifications.

In this work, tapered/etched multicore fiber (MCF) probes are spliced with multimode fiber (MMF) to fabricate the sensor structure. To improve sensitivity, gold nanoparticles (AuNPs) and molybdenum disulfide nanoparticles (MoS ₂ -NPs) are used to immobilize both probes. Synthesized AuNPs and molybdenum disulfide (MoS ₂ )-nanoparticles (NPs) have peak absorption wavelengths of 519 and 330 nm, respectively. High-resolution transmission electron microscopy is used to examine the morphology of the NPs. The scanning electron microscope (SEM) is used to characterize the NP-immobilized optical fiber sensor structures, and SEM-EDX is used to verify the NP-coating over fiber structure. The functionalization of the acetylcholinesterase enzyme over the NP-immobilized probe increases the specificity of the sensor later on. Finally, the developed sensor probes are tested by detecting various acetylcholine concentrations. In addition, performance analyses, such as reusability, reproducibility, and selectivity (in the presence of ascorbic acid, glucose, dopamine, and uric acid), are carried out, and proposed biosensors are experimentally evaluated. The developed tapered fiber sensor with a sensitivity of 0.062 nm/ $\mu \text{M}$ can detect even very low concentrations, such as 14.28 $\mu \text{M}$ , over a wide detection range of 0–1000 $\mu \text{M}$ .