Photonic Crystal Microsphere-Based SERS Biosensor for Ultrasensitive Detection of Aflatoxin B1 in Feed

Aflatoxin B1 (AFB1), a highly carcinogenic mycotoxin, poses significant threats to feed safety and human health, even at trace levels. To address the demand for trace detection of AFB1, we proposed a surface-enhanced Raman scattering (SERS) sensor based on photonic crystal microspheres (PCMs) for a wide-range and ultrasensitive quantitative detection of AFB1. This sensor employed SERS nanotags of gold-silver core-shell nanostars embedded with Raman reporter molecules as the enhancement substrate. Its surface protrusions can generate strong plasmon resonance, which further forms extremely intense "hot spots"a structural feature that renders it significantly superior to spherical nanoparticles in trace detection. Experimental results demonstrate that the developed sensor exhibits an excellent detection performance. Furthermore, benefiting from the unique structural color of PCMs, the sensor is capable of detecting trace amounts of AFB1 in complex matrices. The limit of detection (LOD) reached 0.988 pg/mL, and the linear dynamic range (LDR) was from 1 pg/mL to 100 ng/mL. Additionally, the sensor exhibits excellent specificity, reproducibility, and stability. After 14 days of storage, the sample retained 89.2% of its initial performance. In practical applications, it showed good consistency with commercial enzyme-linked immunosorbent assay (ELISA) kits. All of these results demonstrate that the proposed method has great potential for trace detection and is expected to provide a novel integrated analytical platform with low background, high sensitivity, and a wide detection range for feed safety monitoring.