TMB immobilization catalytic enhanced immunochromatographic platform capacitated with porphyrin-boosted Au nanozyme towards point-of-care (POC) MMP-9 detection

The demand for sensitive and simple point-of-care (POC) diagnostics has driven the innovation of immunochromatographic assays (ICAs), particularly in catalytic enhancement for superior sensitivity. However, the evolution of nanozyme-catalyzed ICAs has been impeded by the complexities of nanozyme preparation and the intricacies of the catalytic enhancement process, all of the above operations demanding precise manipulation. In this work, we present a dual-pronged revolution in catalytic enhancement ICAs. First, for the facile nanozyme acquisition, porphyrin-boosted Au nanoparticles (ProAu NPs) fabricated with high brightness-catalytic properties were raised by a one-pot synthesis strategy. Among ProAu NPs, Au NPs serve as the core for colorimetric and catalytic activity, while porphyrins act as dopants, enhancing the energy absorption and electron transfer efficiency of the Au NPs, and offering the possibility of realizing a two-signal readout strategy. Second, for the catalytic enhancement process majorization, the TMB fixation catalytic enhanced immunochromatographic assay (TFC-ICA) platform was created by immobilizing the chromogenic substrate TMB on the NC membrane, which improves the operability and accessibility of catalysis-enhanced ICAs. Ultimately, the user-friendly system allows ICA signal enhancement with the simple application of an H₂O₂-containing activator onto the NC membrane. The TFC-ICA capacities with ProAu NPs designed for the detection of MMP-9 boasts the ultrasensitive visual detection limit of 4 ng mL⁻¹ level, marking a 12.5–20 times increase in sensitivity over traditional colloidal gold ICAs and other developed ICAs. This approach transcends the constraints of conventional catalysis enhancement ICA and charts new territory for the functional modification of commercial Au NPs in diagnostic applications.