The "umbrella of tolerance": Nanobodies-armed photothermal lateral flow immunoassay for the detection of staphylococcal enterotoxin B

Improving the stability and sensitivity of lateral flow immunoassay (LFIA) is an eternal theme in the field of analytical chemistry, and the recent emergence of new molecular recognition element (MRE) and various detection signal offer potential biological and technical possibilities. Here, we innovatively report a nanobodies (Nbs)-armed photothermal lateral flow immunoassay (NLFIA) in which Nbs act as the "umbrella of tolerance", greatly improving the stability of LFIA. Meanwhile, this is complemented by Au core-petal nanoparticles (CPNs), a photothermal material synthesized by a polydopamine (PDA)-assisted two-step method, to enhance the sensitivity of the readable signal. Following proof of concept in staphylococcal enterotoxin B (SEB), we find that the novel NLFIA not only "suits the case" to improve the tolerance of the strips to the detection environment and the specificity of the target, but also increases the accuracy and comprehensibility of the analysis results on the premise of ensuring the detection sensitivity. The detection limit of NLFIA is 1.68 ng mL-1 (colorimetric mode) and 0.58 ng mL- 1 (photothermal mode), which is 25-fold lower than gold standard approach (14.80 ng mL-1). In addition, the proposed method is successfully applied to the detection of SEB in food with high accuracy. This study integrates the novel MRE with photothermal LFIA to provide a reference for the development of a more sensitive and stable platform for the detection of foodborne contaminants.