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Background-Free Chromatographic Detection of Sepsis Biomarker in Clinical Human Serum through Near-Infrared to Near-Infrared Upconversion Immunolabeling

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posted on 09.12.2020, 15:33 by Tianxing Ji, Xinqiang Xu, Xindong Wang, Ning Cao, Xiaorui Han, Minhong Wang, Bo Chen, Zhen Lin, Hongyun Jia, Min Deng, Yong Xia, Xuguang Guo, Meng Lei, Zhenwei Liu, Qiang Zhou, Guanying Chen
Luminescence nanomaterial-based lateral flow assay (LFA) is promising for point-of-care tests. However, the detection sensitivity and accuracy are often affected by the interferences of autofluorescence and photon scattering from nitrocellulose membrane and colored plasma. Here, we describe a near-infrared to near-infrared upconversion nanoparticle (UCNP) immunolabeled LFA for background-free chromatographic detection of sepsis biomarker procalcitonin (PCT) in clinical human plasma. This upconversion immunolabeling enables both light excitation (at ∼980 nm) and anti-Stokes emission (at 800 nm) to be adopted within the first biological window (700–1000 nm), which eliminates background autofluorescence as well as photon scattering interferences, empowering a high-sensitivity detection without complicated procedures. After optimization, the described assay presented a limit of detection reaching down to 0.03 ng/mL, lower than the normal level (0.05 ng/mL), while having a detection range of 0.03–50 ng/mL that covers the clinical PCT level of interest (0.5–10 ng/mL). The assay recoveries in human serum samples were evaluated to be about 95–110%, whereas the inter- and intra-assay coefficient variations were both determined to be below 15%. Importantly, measured PCT concentrations in clinical samples are in good correlation with that of the electrochemiluminescence immunoassay (Roche) widely applied in large clinical settings. This near-infrared to near-infrared upconversion immunolabeling approach has direct implications for ultrasensitive and background-free point-of-care detection of other serum biomarkers in resource-limited clinical settings.

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