Development of quantum dot‐based fluorescence lateral flow immunoassay strip for rapid and quantitative detection of serum interleukin‐6

BACKGROUND Interleukin-6 (IL-6) is an inflammatory factor that increases rapidly in response to infectious diseases including sepsis. The aim of this study is to develop a quantum dot (QD)-based fluorescence lateral flow immunoassay (LFIA) strip that can rapidly and accurately detect IL-6 levels. METHODS QD-based LFIA strips were fabricated by conjugating CdSe/ZnS QDs to the IL-6 antibody. Performance verification and clinical sample analysis were carried out to evaluate the newly developed strip. RESULTS QD-based LFIA strips were successfully fabricated. The test strip's linear range was 10-4000 pg/ml, with a linear correlation coefficient of R2  ≥ .959. The sensitivity of the test strip was 1.995 pg/ml. The recovery rate was 95.72%-102.63%, indicating satisfying accuracy. The coefficient of variation (CV) of the intra-assay was 2.148%-3.903%, while the inter-assay was 2.412%-5.293%, verifying the strip's high precision. The cross-reaction rates with various interleukins (IL-1α, IL-1β, IL-2, IL-4, and IL-8) and interferon-γ (IFN-γ) were all <0.1%. When the strip was placed in a 50°C oven for 1, 2, 3, and 4 weeks, the test results were not significantly altered compared to storage at room temperature. Furthermore, 200 clinical serum samples were analyzed to compare the strip with the Beckman chemiluminescence immunoassay (CLIA) kit, which revealed a high correlation (n = 200, R2  = .9971) for the detection of IL-6. CONCLUSIONS The QD-based test strip can rapidly and quantitatively detect IL-6 levels, thus meeting the requirement of point-of-care test (POCT) and showing excellent clinical prospects.