Peptide molecular lock-engineered nanobodies enable an oriented dual-modal immunoassay for reliable detection of Cronobacter sakazakii.

Authors

Pengyu Chen, Jiahao Zhang, Yuxia Luo, Sijie Liu, Yuechun Li, Bingzhi Li, Jing Sun, Guo Hao, Jianlong Wang, Yanru Wang

Published in

Food chemistry. Volume 525. Issue Pt 1. Pages 150387. Jul 11, 2026. Epub Jul 11, 2026.

Abstract

Conventional nanobody ELISAs for trace Cronobacter sakazakii in powdered infant formula suffer from random orientation and low signal output. We developed an oriented dual-modal immunoassay that combines site-specific biotinylation via a C-terminal AviTag and a peptide molecular lock, enabling controlled surface orientation while preserving nanobody structural integrity. This strategy was further integrated with phage-displayed nanobodies for multivalent amplification and both fluorescent and colorimetric readouts. The assay exhibited a broad linear range of 10³-10⁶ CFU/mL, with limits of detection (LODs) of 6.70 × 10² CFU/mL for fluorescence and 1.55 × 10³ CFU/mL for colorimetry, showing improved sensitivity compared with the conventional passive adsorption-based Nb-ELISA evaluated in this study. XGBoost-based multimodal fusion improved quantitative accuracy, and SHAP analysis elucidated modality contributions. In spiked powdered infant formula samples, recoveries ranged from 92.1% to 118% with coefficients of variation below 5.98%, confirming acceptable matrix tolerance and analytical reliability.

PMID:
42447597
Bibliographic data and abstract were imported from PubMed on 15 Jul 2026.

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