Monitoring biomaterials with light and smart materials for biosensing applications

The rapid evolution of optical biosensors has revolutionized molecular detection in medical diagnostics, environmental monitoring, and food safety, offering label-free, real-time, and high-sensitivity capabilities. Despite their advantages, conventional optical biosensors face inherent limitations in resolving sub-wavelength structures and detecting ultra-low concentration analytes in real time. To overcome these diffraction-limited constraints, this review critically examines the integration of plasmonic phenomena – specifically surface plasmon resonance and localized surface plasmon resonance – with advanced fiber-optic architectures. This study analyzes the mechanistic shifts from traditional evanescent wave confinement in tapered and U-shaped fibers to hybrid plasmonic-fiber configurations that significantly enhance electromagnetic field interactions. Special emphasis is placed on the role of nanomaterials, including noble metal nanoparticles (gold and silver) and metal oxides such as zinc oxide, in amplifying sensitivity and selectivity. Furthermore, this study surveys recent advancements in deep-learning-assisted optimization algorithms designed to interpret complex spectral data and improve detection limits for biomarkers, pathogens, and nucleic acids. By synthesizing current practical performances and addressing existing challenges in miniaturization and integration, this work highlights the transformative potential of smart plasmonic biosensors in next-generation biomedical diagnostics and wireless sensing applications.