S-Tapered WaveFlex Biosensor Based on Multimode Fiber and Seven-Core Fiber Composite Structure for Detection of Alpha-Fetoprotein

Alpha-fetoprotein (AFP), a biomarker for liver cancer detection, has important clinical significance. Here, an S-tapered WaveFlex fiber biosensor is developed that is based on the structure of multimode fiber (MMF)–multicore fiber (MCF)–MMF and leaks more energy when excited by light. ZnO nanowires (ZnO-NWs)/WS2 nanosheets (WS2-NSs) and gold nanoparticles (AuNPs) are functionalized on the probe surface to further enhance the sensing performance. 1-D ZnO-NWs possess a larger specific surface area and can provide more sites for antibodies. The fold structure of WS2-NSs provides ample space for functionalization. The combination of the above two nanomaterials is conducive to the immobilization of AuNPs and AFP antibodies and improves the performance of the developed biosensor. AuNPs and AFP antibodies are used to generate localized surface plasmon resonance (LSPR) and enhance the specificity of the probe, respectively. The developed probe is employed to detect AFP solution in the range of 0–1000 ng/mL, and the sensitivity and limit of detection (LoD) are obtained as 1.32 nm/log(ng/mL) and 84 pg/mL, respectively. Moreover, the practical application capability of the probe is verified by the selectivity test, pH test, reproducibility, and reusability experiments. The results demonstrate the potential application of the developed S-tapered WaveFlex AFP sensor in the detection of liver cancer markers.