Starfish-like gold nanotags aggregation induced high density hot-spots to boost surface-enhanced Raman scattering...

Aspergillus niger, a key functional microorganism widely employed in food fermentation processes, also poses significant health risks as numerous strains are capable of producing hazardous mycotoxins. This nature necessitates the development of rapid and accurate detection techniques. In this study, a highly sensitive surface-enhanced Raman scattering (SERS) biosensor based on silicon microchips and aptamer-functionalized gold nanotags was constructed for ultrasensitive detection of Aspergillus niger. A key innovation lies in the design of a trifunctional probe integrating gold nanostars, the Raman reporter 4-ethynylaniline (4-EBZN), and a specific aptamer, which enhances both signal amplification with an enhancing factor 2.4 × 10⁸. The biosensor capitalizes on cascaded electromagnetic hotspots generated by the branched architecture of gold nanostars, achieving an exceptionally low detection limit of 1 CFU·mL^-1 with high specificity and no cross-reactivity toward non-target microorganisms. When validated in Pu-erh tea, soy sauce, and drinking water samples, the biosensor exhibited excellent spiked recoveries ranging from 95.13% to 104.90%, along with strong correlation (R² > 0.99) with conventional plate counting. Furthermore, the biosensor demonstrated outstanding reproducibility (RSD < 4.3%), long-term stability over one month, and a rapid detection time of forty-five minutes, positioning it as a highly promising tool for food safety monitoring.