Development of dual quantum dots-based fluorescence-linked immunosorbent assay for simultaneous detection on inflammation biomarkers

Abstract

Simultaneous detections of different but clinically relevant biomarkers are of extremely importance in biomedicine. Due to their unique photophysical properties, quantum dots (QDs) are ideally suited for highly sensitive multiplexed determination. Herein, a dual quantum dots-based fluorescence-linked immunosorbent assay (dQDs-FLISA) for simultaneous and quantitative detection of inflammation biomarkers (i.e. serum amyloid A (SAA) and C-reactive protein (CRP)) has been established. After being coated by amphiphilic oligomers (polymaleic acid n-hexadecanol ester, PMAH), the red-QD and green-QD with high quantum yields were used as fluorescence probes to couple SAA and CRP antibodies, respectively. Cross-reactivity among the SAA and CRP’s antibodies and antigens have been carefully examined by interference experiments, and it was successfully avoided by the specific probe adding sequence. Therefore, the assay provided a broad linear analytical range, including SAA quantitative range of 10–1,000 ng mL−1 with linear correlation (R2) of 0.992, and CRP quantitative range of 10–1,000 ng mL−1 with R2 of 0.998. The limit of detections (LODs) for SAA and CRP using dQDs-FLISA were 2.39 ng mL−1 and 6.37 ng mL−1, respectively. The accuracy of the assay has been confirmed with recoveries of 92.13%–101.85%. More importantly, the assay results showed good specificity, the QD-antibody probe could couple corresponding antigen (CRP or SAA) high-efficiently and it could be out of interference of other antigens and substances in serum. Given its good performance, the proposed dQDs-FLISA method offers great potential for simultaneous and quantitative detection of other biomarkers in in vitro diagnostic (IVD).