LAUSR

Graphical abstract Figure. No caption available. HighlightsA one‐pot, simple and convenience method to synthesize Fe3O4 nanocrystal clusters.Highly sensitive and magnetic quantitative lateral flow immunoassay is developed.Trace‐level antibody, NT‐proBNP, is detected at a point‐of‐care manner.Quantitative linear relationship between signal and antibody concentration is set up. ABSTRACT Lateral flow immunoassay (LFIAs) has found widespread applications in point‐of‐care testing (POCT). However, conventional LFIAs based on gold nanoparticles can only provide limited information (qualitative or semi‐quantitative information) and suffer from low sensitivity. To address this issue, we developed a Fe3O4 nanocrystal cluster‐based highly sensitive LFIAs for the simultaneously qualitative and quantitative detection of trace‐level biomarkers. The synthesis of poly (acrylic acid)‐stabilized superparamagnetic nanocrystal clusters (PAA‐MNCs) is a one‐pot, simple and convenient technique, and the polyelectrolyte coating provides enough stability, good dispersity and downstream conjugation sites. Using these PAA‐MNCs as a label nanomaterial in LFIAs, a model biomarker (amino‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) antibody) was detected qualitatively and quantitatively. The results show that tests have a qualitative detection limit of 100 pg/mL and a quantitative linear relationship between the magnetic signal and antibody concentration (20–8000 pg/mL) under the optimized experimental conditions. The developed LFIA based on PAA‐MNCs for NT‐proBNP could be used for the clinical assessment of heart failure, offering tremendous potential for personalized medicine.