Surfactant-assisted synthesis of water-stable cobalt-imidazole metal organic frameworks as signal probes for chemiluminescent immunoassay

Abstract

Application of metal-organic frameworks (MOFs) as signal probes for immunoassay has been greatly hampered by their chemical instability in aqueous solutions. To reduce the attack of water molecules and improve the water stability of MOFs, cetyltrimethyl ammonium bromide (CTAB) was used as a capping reagent to form a hydrophobic protective layer on the surface of MOFs. The Co-MOFs synthesized with CTAB-assisted approach (CTAB-Co-MOFs) can keep stable in water for no less than 45 days, while the stationary duration of those without CTAB assistance is only 3 days. The CTAB-Co-MOFs can vastly catalyze the reaction between luminol and H2O2, and generate very intensive chemiluminescent (CL) emission. The results of mechanism study show that CTAB-Co-MOFs are capable of promoting the generation of reactive oxygen species. Attributing to the improved water stability and outstanding catalytic activity of CTAB-Co-MOFs, a competitive immunoassay method was established for detecting acetamiprid by adopting them as CL probes. It shows a linear range of 0.01–25 ng mL-1 and a detection limit of 4.77 pg mL-1 (3σ). Successful detection of herbal medicines spiked with acetamiprid validated the accuracy of the CTAB-Co-MOFs-based immunoassay method. This work implies the possibility of using water-stable CTAB-Co-MOFs for tracing biological binding events.