Fabrication of Top–Down-Based Optical Fiber Nanoprobes and Their Diagnostic Application for Pancreatic Cancer

Top–down nanoparticle fabrication has been studied to improve reusability, durability, and reproducibility in bottom–up nanoparticle-based fiber-optic plasmonic sensors. Gold nanostructures were simply and inexpensively patterned onto optical fibers via nanosphere lithography. To compensate for their low sensitivity, a sandwich assay was incorporated. The nanotriangle and nanohole were characterized through refractive index sensing, which was also carried out in the bottom–up gold nanospheres. The immune responses for pancreatic cancer biomarker (carbohydrate antigen 19-9) were real-timely detected and compared in three structures. When a sandwich assay was applied to improve the detection limit, a lowest detection limit of 0.25 U/mL was achieved in the triangle-based plasmonic nanoprobe, which is approximately 700 times lower than the reference value. Based on these results, all the manufactured fiber-optic sensors were sufficiently applicable as biosensors. In particular, commercialization is expected as reliable and cost-effective devices in patterned nanostructures-based optrodes by upgrading sensitivity with sandwich immunoassay.