Controllable assembly metal-organic frameworks and gold nanoparticles composites for sensitive immunochromatographic assay

Abstract

Creating universal signal labels from fundamental building blocks with excellent biocompatibility and well-controlled size/uniformity simultaneously for immunochromatographic assay (ICA) is highly desired but extremely challenging. Here, a nano-signal label strategy was reported, in which the amino-terminated zirconium MOFs (NU66) are adopted to construct powerful matrix materials and gold nanoparticles (AuNPs) act as the linker between metal-organic frameworks (MOFs) and antibodies. Particularly, AuNPs were immobilized directly on the surface of NU66, giving NU66 excellent biocompatibility with bright color signal labels and improving the salt ion stability of AuNPs. As a proof of concept, the furazolidone residues was monitored by the developed NU66@AuNPs-ICA in food samples (pork, shrimp and eggs). With 3-[(4-carboxyphenyl) monomethyl] amino-2-oxazolidinone (CPAOZ) as analyte target, the visual limit of detection (vLOD) and cut-off level were 0.6 ng/mL and 3.0 ng/mL, respectively. This work may open a new avenue for the application of MOFs in immunochromatography assays.