Near-infrared Persistent Luminescence Nanoparticles-Based Immunochromatographic Assay for Autofluorescence-free Detection

Fluorescent immunochromatographic test strips are critical for highly sensitive, rapid detection. However, their sensitivity for detecting trace biomarkers is often affected by autofluorescence and photon absorption of the samples (nitrocellulose membrane substrates and blood chromophores). Here, we report for the first time an immunochromatographic test strip based on near-infrared (NIR) persistent luminescence nanoparticles (PLNPs) for the highly sensitive detection of the biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP). NIR PLNPs exhibit long NIR persistent luminescence (PersL) properties after excitation, allowing separation of excitation and detection, thereby eliminating sample autofluorescence interference. In addition, the PersL in the NIR region greatly reduces the absorption of photons by the sample, further improving the detection sensitivity. After optimization, the test strips can detect NT-proBNP at levels as low as 15.28 pg/mL, which covers the required clinical detection range. The assay demonstrated a recovery rate of 94–101% in human serum samples, and the inter and intrabatch coefficients of variation were less than 15%. The concentrations of NT-proBNP measured in clinical samples correlated well with those of the Roche electrochemiluminescence immunoassay, which is widely used in clinical practice. This NIR PersL immunochromatographic test strip has potential applications in the highly sensitive and immediate detection of trace biomarkers.