Quantitative and simultaneous detection of two inflammation biomarkers via a fluorescent lateral flow immunoassay using dual-color SiO 2 @QD nanotags

An on-site detection strategy is reported based on dual-color SiO2@quantum dot (QD)-integrated lateral flow immunoassay (LFA) strip to realize the quantitative and simultaneous detection of C-reactive protein (CRP) and procalcitonin (PCT) in serum. The dual-color SiO2@QD nanotags with monodispersity and excellent luminescence were synthesized using polyethyleneimine-mediated electrostatic adsorption of dense red CdSe/ZnS-COOH (excitation/emission 365/625 nm) or green CdSe/ZnS-COOH (excitation/emission 365/525 nm) QDs on the surface of 180 nm SiO2 spheres and were conjugated with anti-PCT and anti-CRP monoclonal antibodies, as stable and fluorescent-enhanced QD nanotags in the LFA system. The use of SiO2@QDs with two different fluorescent signals caused the sensitivity and specificity of the multiplex LFA system. As a result, the proposed assay provided a wide logarithmic determination range with a CRP quantitative range of 0.5-103 ng/mL and PCT quantitative range of 0.05-103 ng/mL. The limits of detection (LODs) of CRP and PCT reached 0.5 and 0.05 ng/mL, respectively. The SiO2@QD-based LFA showed great potential as rapid detection tool for the simultaneous monitoring of CRP and PCT in serum sample.