An
outbreak of coronavirus disease (COVID-19) caused by severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses great
threats to human health and the international economy. To reduce large-scale
infection and transmission risk of SARS-CoV-2, a simple, rapid, and
sensitive serological diagnostic method is urgently needed. Herein,
an aggregation-induced emission (AIE) nanoparticle (AIE810NP, λem = 810 nm)-labeled lateral flow immunoassay
was designed for early detection of immunoglobulin M (IgM) and immunoglobulin
G (IgG) against SARS-CoV-2 in clinical serum samples. Using a near-infrared
(NIR) AIE nanoparticle as the fluorescent reporter (△λ
= 145 nm), the autofluorescence from the nitrocellulose membrane and
biosample and the excitation background noise were effectively eliminated.
After optimization, the limit of detection of IgM and IgG is 0.236
and 0.125 μg mL–1, respectively, commensurate
with that of the enzyme-linked immunosorbent assay (ELISA) (0.040
and 0.039 μg mL–1). The sensitivity of the
proposed AIE810NP-based test strip for detecting IgM and
IgG is 78 and 95% (172 serum samples), commensurate with that of ELISA
(85 and 95%) and better than that of a commercial colloidal gold nanoparticle
(AuNP)-based test strip (41 and 85%). Importantly, the time of detecting
IgM or IgG with an AIE810NP-based test strip in sequential
clinical samples is 1–7 days after symptom onset, which is
significantly earlier than that with a AuNP-based test strip (8–15
days). Therefore, the NIR-emissive AIE nanoparticle-labeled lateral
flow immunoassay holds great potential for early detection of IgM
and IgG in a seroconversion window period.