Taper-in-taper fiber structure-based LSPR sensor for alanine aminotransferase detection

Alanine aminotransferase (ALT), a critical component of human blood, is inextricably associated with liver injury. The current study develops a novel biosensor based on the localized surface plasmon resonance (LSPR) principle for the detection of ALT analytes at concentrations ranging from 0 to 1000 Units per liter (U/L). According to the authors' knowledge, this is the first time an optical fiber structure with a taper-in-taper structure has been developed for biosensing applications. It is fabricated using the three-electrode semi-vacuum taper technique and is characterized using a combiner manufacturing system. Gold nanoparticles (AuNPs), molybdenum disulfide nanoparticles (MoS 2 -NPs), and cerium oxide nanoparticles (CeO 2 -NPs) are immobilized on the sensing region to improve the sensing performance. Prior to application, these nanoparticles are characterized using a high-resolution transmission electron microscope (HR-TEM) and a UV-Visible spectrophotometer. AuNPs promote the LSPR phenomenon, whereas MoS 2 -NPs/CeO 2 -NPs contribute to the sensor probe's biocompatibility and stability. Following that, the probe surface was functionalized with glutamate oxidase (GluOx) to improve selectivity. The probe demonstrated an excellent linear relationship with the subsequent assay's ALT concentration. Additionally, the probe's performance characteristics such as reusability, reproducibility, stability, and selectivity are evaluated in order to determine its clinical utility in diagnosing liver injury.