AuNPs-VS₂-Mediated LSPR-SPR-Coupled optical fiber biosensor for sensitive and acid-stable detection of H. pylori

Early detection of Helicobacter pylori (H. pylori) is critical for preventing gastric diseases and associated carcinogenesis. However, current clinical methods, such as serology and endoscopic biopsy, are often highly invasive or time-consuming, limiting their utility for real-time and in vivo diagnosis. To address this gap, an AuNPs-VS₂ composite-sensitized optical fiber surface plasmon resonance (SPR) biosensor was developed for rapid and highly sensitive H. pylori detection. Multilayered 1T-phase VS₂ was synthesized to enhance the interfacial electric field and provide abundant sites for antibody immobilization. Positively charged AuNPs were then self-assembled onto carboxylated VS₂, enabling synergistic LSPR-SPR coupling and an amplified refractive index response. The optimized probe achieved a refractive index sensitivity of 3718.04 nm/RIU and exhibited a good linear detection range for H. pylori from 10¹ to 10⁷ CFU/mL, with a sensitivity of 0.88 nm·(lg CFU/mL)^-1 and a limit of detection as low as 1.67 CFU/mL. Furthermore, the biosensor demonstrated excellent selectivity, stable signal output, a rapid response time of approximately 34 s, strong acid stability over a pH range of 1-5, and low biotoxicity, underscoring its potential for gastric fluid analysis and future in vivo diagnostic applications.