Novel raspberry-like AuAgPd nanospheres bidirectional driven nanobody-based immunochromatographic strip for sensitive detection of aflatoxin B1

Aflatoxin B 1 (AFB 1 ), a highly toxic mycotoxin that frequently contaminates food matrices, has raised significant global public health concerns. Traditional colloidal gold immunochromatographic test strips (ICTS) lack sufficient accuracy for on-site AFB 1 detection. Herein, an inner filter effect (IFE)-based dual-signal (fluorescence-colorimetric) immunosensor was developed. Raspberry-like trimetallic AuAgPd nanospheres (RTNPs) were synthesized as efficient quenchers for aggregated quantum microspheres (AQMs), while nanobody G8 served as the recognition element. The sensor enables dual-mode AFB 1 detection within 10 min, with detection limits of 10.2 pg/mL (fluorescence) and 14.9 pg/mL (colorimetric). Compared to colloidal gold-based ICTS, the sensitivity was improved by 3-fold and 9-fold for fluorescence “turn-on” and colorimetric “turn-off” modes, respectively. In spiked recovery experiments using corn samples, recovery rates ranged from 95.5 % to 103.1 % (fluorescence) and 98.6 % to 104.6 % (colorimetric), with relative standard deviations (RSDs) below 7 % for both modes. In summary, the developed dual-signal immunosensor demonstrates favorable sensitivity and accuracy for AFB 1 detection. Its effectiveness has been successfully verified in actual corn samples, providing a valuable reference for rapid on-site detection of AFB 1 and offering substantial practical value for enhancing food safety monitoring. • Raspberry-like AuAgPd trimetallic nanospheres were first applied to ICTS. • The nanobody G8 replaced the conventional monoclonal antibody as the recognition element. • Fluorescent-colorimetric dual-mode signal ensured high sensitivity while enhancing detection accuracy. • AuAgPd@G8-AQMs-ICTS generated both fluorescent and colorimetric signals within 10 min. • Compared to AuNPs-ICTS, AuAgPd-ICTS exhibited 3-fold and 9-fold higher sensitivity in the fluorescent "turn-on" and colorimetric "turn-off" modes, respectively.