Recent Advances in Nanoparticle-Based Biosensors for Campylobacter jejuni Detection in Foods: Mechanisms, Designs, and Applications

Campylobacter jejuni, which is mostly transmitted through poultry products, is one of the most common bacterial causes of foodborne illness worldwide. Its low infectious dose and complex chicken matrices make reliable identification difficult, and conventional culture- and nucleic acid-based methods are still time-consuming and unsuitable for rapid or portable food safety surveillance. With a focus on food and food-chain-related matrices, this study critically assesses nanoparticle (NP)-based biosensors designed for C. jejuni detection. The functional roles of NPs, sensing mechanisms, nanomaterial classes, biosensing systems, application settings, comparative analytical performance, current issues, new trends, and methodological limitations are evaluated. NPs play function-driven roles in C. jejuni biosensing, including enzyme-mimetic or catalytic activity, target capture and separation, and signal amplification and transmission. These functions operate independently of tailored platform configurations and support immunosensor-, aptamer-, nucleic acid-, and whole-cell-based detection techniques. NP integration improved test sensitivity, signal robustness, and operational flexibility via immunomagnetic separation, plasmonic enhancement, catalytic signal creation, and dual-mode signal transduction techniques. Comparative studies revealed reproducible performance declines in complex food matrices compared to buffer systems, showing unresolved matrix effects and repeated pretreatment requirements. Several biosensors have been employed in milk, poultry, and model food systems. However, unified validation against reference procedures and validation utilizing naturally contaminated samples are still lacking. Although NP-based biosensors for C. jejuni constitute a well-established and varied analytical field, ongoing advancement will depend on increased reliability, standardized validation, and compliance with actual food safety regulations.