MOF scaffold for anchoring platinum-nickel nanoparticles with enhanced oxidase-like activity to improve lateral flow immunoassay diagnosis.

Noble metal nanoparticles have attracted tremendous attention as the promising signal reporters for catalytic-colorimetric lateral flow immunoassay (LFIA). However, it remains great challenges for improving their stability and catalytic activity. Herein, first, a kind of porphyrinic based metal-organic framework (MOF) was used as a carrier for loading platinum (Pt) nanoparticles to avoid its aggregation. Moreover, nickel (Ni) atoms were dopped into Pt nanoparticles to adjust crystal structure, thus greatly improving catalytic activity. The resulting MOF@PtNi nanocomposite showed enhanced colorimetric signal brightness and excellent oxidase-like activity, which can improve sensitivity via amplifying the color signal. The catalytic mechanism was further studied by scavenger and electron paramagnetic resonance analysis. Furthermore, integrated with the competitive immunization LFIA platform, the high sensitivity colorimetric detection of human immunoglobulin G was realized with a detection limit of 0.378 ng/mL and 0.269 ng/mL for pre- and post-catalytic detection, respectively. In addition, this MOF@PtNi based catalytic-colorimetric LFIA was used for detection of clinical serum samples and the results agreed well with that measured by the standard method. Therefore, this study helps open up the application of proposed catalytic-colorimetric nanocomposite in the ultrasensitive LFIA for point-of-care diseases diagnosis.