A novel triple-signal biosensor based on ZrFe-MOF@PtNPs for ultrasensitive aflatoxins detection.

The development of more sensitive, stable, and portable biosensors is crucial for meeting the growing demands of diverse and complex detection environments. MOF-based nanozymes have emerged as excellent optical reporters, making them ideal signal donors for constructing multi-signal lateral flow immunoassays (LFIA). In this study, a ZrFe-MOF@PtNPs nanocomposite was synthesized by uniformly depositing platinum nanoparticles (PtNPs) onto the surface of ZrFe-MOFs using an impregnation-reduction method. The ZrFe-MOF@PtNPs exhibited broad absorption spectra, excellent peroxidase-like activity (SA = 21.77 U/mg), high solvent stability, and efficient antibody binding capability. A portable LFIA platform was developed based on ZrFe-MOF@PtNPs and a smartphone for the targeted detection of carcinogenic aflatoxins. This method enabled the readout of colorimetric, fluorescent, and catalytic signals, significantly enhancing detection sensitivity, ensuring result accuracy, and expanding the dynamic detection range. For aflatoxin M1, the calculation of the detection limit of the three signal modes reached as low as 0.0062 ng/mL, which is two orders of magnitude more sensitive than AuNPs-LFIA (0.1839 ng/mL). This study provides effective guidance for multifunctional modification of MOFs and serves as a reference for the application of MOF-based nanozymes in point-of-care biosensors.