A Nanostructured Microarray-Based SERS Sensor Targeted at Multiplex Mycotoxins Detection in Food and Feedstuff Using Handheld Apparatus

Food and agricultural commodities contamination by various toxigenic molds is a seriously neglected problem, affecting ~25% of the world’s crops with staggering economic losses. Regardless of decades of extensive research, mycotoxins continue to penetrate the food chain through food and feed crops and pose health risks to humans and livestock. Herein, we present a newly developed nanostructured microarray (5 by 5 sensing spots) based on silver-coated porous silicon used as a surface-enhanced Raman scattering (SERS) transducer. The unique microarray was facilitated without the need for any micro/nano-fabrication (clean-room) facilities. The inherent surface void and pore morphology (82±2% and ca. &lt; 9 nm, respectively) were physically optimized to augment the SERS effect while achieving an enhancement factor of &gt; 1.03 × 10⁸. Under optimized conditions, three common mycotoxins (aflatoxin B1, fumonisin B1 and ochratoxin A) in feed ingredients and agricultural products were simultaneously assessed using a portable Raman device (1.5 µL sample analyzed in 30 min). The optical response was inversely proportional to the metabolite concentration upon selective interaction with anti-target mycotoxin aptamers modified sensing spots. The calculated limits of detection were 0.01, 0.6 and 0.9 ng/mL (part per billion, ppb) for aflatoxin B1, fumonisin B1 and ochratoxin A, respectively, within the dynamic range of 0.1-1000 ppb. Furthermore, the selectivity, regeneration and overall shelf-life were thoroughly evaluated while depicting satisfactory performances (no interferences with interfering mycotoxins, four regeneration cycles and five weeks of stability, respectively). Finally, the practicality of the developed SERS assay was elucidated in various matrices (<i>e.g.,</i> maize, rice and wheat), with recovery values of 95–103%. The successful validation of actual samples' analysis emphasizes the platform's reliability, robustness and suitability for practical use of multi-target analytes detection, including on-site operation.