Gold-tetrahedron DNA nanoflare probe-based fluorescent immunoassay for glyphosate detection

Glyphosate (GLYP) is the most widely used herbicide across the world. Among GLYP sensing strategies, fluorescent methods stand out for efficiency and intuitive characteristics. However, the complex synthesis of fluorescent materials of current methods poses limitations for practical applications. Herein, a gold nanoparticle–tetrahedron DNA nanostructures (AuNP-TDNs) nanoflare probe with controllable fluorescence “turn on” response was synthesized for GLYP detection. Both goat anti-rabbit antibody and fluorescent dye SYBR Green I stained TDNs (TDNs-SG) were modified on the AuNPs. TDNs-SG, which functioned as flare DNAs for signal amplification, exhibited initial fluorescence quenching induced by AuNPs via nanosurface energy transfer (NSET). In the presence of GLYP, a competitive immuno reaction with rabbit anti-GLYP antibodies occurred. The probe was immobilized on the detection substrate via the goat anti-rabbit antibody. Upon treatment with dithiothreitol (DTT), TDNs-SG was released from AuNPs leading to fluorescence recovery. This fluorescence immunoassay demonstrated a linear detection range (0.5–32 μg g⁻¹) and a limit of detection of 0.18 μg g⁻¹ . The method showed negligible cross-reactivity (<0.01 %) with GLYP analogues. The AuNP-TDNs nanoflare probe can be synthesized within 3 h under gentler condition (at 4 °C or room temperature). These simply prepared AuNPs-TDNs nanoflare probes offer a reliable and precise fluorescence “turn-on” platform for rapid detection of GLYP.