Optical Fibers in Immunosensing: Developments, Materials, and Biological Applications

Abstract

Optical fiber immunosensors have emerged as a versatile class of analytical devices for detecting biomolecules with high sensitivity, rapid response, and the potential for real-time, label-free readout. Their appeal lies in the combination of optical confinement, remote readout, compact geometry, and compatibility with surface functionalization strategies that couple light transduction to antibody-based recognition. Over the last two decades, the field has expanded from simple evanescent-wave and fluorescence-based probes to more advanced grating, interferometric, plasmonic, and optofluidic architectures that can be tuned for applications in cancer diagnostics, infectious disease, food safety, and environmental monitoring. In particular, cancer biology has driven major innovation because early detection of protein biomarkers in serum, tissue, or other biologic fluids can materially affect prognosis and treatment decisions. This review summarizes the operating principles, material platforms, surface functionalization strategies, and analytical performance of optical fiber immunosensors, with balanced coverage of healthcare, food safety, and environmental sensing while prioritizing cancer-related applications. The review also highlights the principal challenges that still limit routine deployment, including reproducibility, antifouling, and scalable fabrication, and outlines future directions towards more robust and clinically usable fiber-based immunosensors.