A versatile nanozyme integrated colorimetric and photothermal lateral flow immunoassay for highly sensitive and reliable Aspergillus flavus detection.

Visual lateral flow immunoassays (LFA) have been recognized as the attractive point-of-care testing (POCT) for bioanalysis; however, they have been constrained by insufficient sensitivity and limited reliability. Herein, combining the catalytic sites of Cu nanoparticles with an inherent photothermal polydopamine (PDA) scaffold via a one-step process, a compact Cu-anchored PDA (PCu) was engineered as the efficient signal element for the multimodal LFA (mLFA). The robust PCu with peroxidase-mimics and photothermal properties, could simultaneously provide triple signal readouts for colorimetric, amplified colorimetric and photothermal detection toward Aspergillus flavus (A. flavus). Attractively, the multiple guaranteed detection of PCu-based mLFA enabled the accurate and sensitive detection of A. flavus mycelium biomass, down to 0.45 and 0.22 ng mL, which was 19- and 40-fold improvements compared to traditional colorimetry. Besides, mLFA was successfully applied to actual samples with satisfactory recoveries from 89.9 to 109%, indicating the highly reliable analytical performance. This work paved a prospective way for the construction of efficient peroxidase-mimics and superior photothermal multifunctional nanomaterials, providing a potential versatile visual POCT platform for analytical events.