Smartphone-assisted plasmonic biosensors for rapid on-site detection of foodborne pathogens and allergens

We report the design of a smartphone-assisted plasmonic immunosensor and its application to the detection of several food contaminants, namely staphylococcal enterotoxin A (SEA), bovine β-lactoglobulin (BLG), and hen egg white lysozyme (LYSO). Comprehensive characterization of antibodies was performed by ELISA and surface plasmon resonance imaging (SPR-i), demonstrating high affinity and specificity for each target, which supports their potential application in complex food matrices. The immunosensing platform utilizes gold nanoparticle-conjugated antibodies and inexpensive glass slides as single-use chips. Both qualitative visual detection by the naked eye down to around 1 ng of BLG, and quantitative detection with a portable spectrophotometer connectable to a smartphone are demonstrated. This self-contained device may provide a rapid, sensitive, and cost-effective approach to food contaminants analysis, potentially useful for on-site food safety assessment.