Dual protecting encapsulation synthesis of ultrastable quantum-dot nanobeads for sensitive and accurate detection of cardiac biomarkers

Abstract

The labeling material is a key factor that determines the ability of lateral-flow immunoassay (LFIA) for accurate and sensitive detection. Herein, a dual protection strategy with both polyvinylpyrrolidone (PVP) winding and SiO2 coating has been first developed for generating quantum dot beads@SiO2-COOH (QBs@SiO2-COOH) nanobeads with high fluorescence and extraordinary stability, which greatly improved the sensitivity and stability of rapid LFIA. QBs@SiO2-COOH showed outstanding colloidal stability in complex matrices and 1,967-fold higher luminescence than that of corresponding QDs. The novel LFIA nanosensor was constructed by utilizing synthesized QBs@SiO2-COOH as the reporter to realize rapid quantitative detection of cardiac troponin I (cTnI) within 10 min using only 60 μL of sample. The limit of detection (LOD) was 0.036 ng mL−1 with the excellent linearity relationship between 0.12 and 125 ng mL−1. Importantly, the detection method owned good reproducibility (CV < 8 %) and predominant stability, which were demonstrated for the first time by detecting clinical serum samples preserved at different temperature in 120 days. Moreover, the developed nanosensor achieved the simultaneous quantitative detection of cTnI, creatine kinase-MB (CK-MB), and myoglobin (Myo). This QBs@SiO2-COOH-based rapid LFIA nanosensor holds a good prospect for rapid, stable and sensitive detection of biomarker for in vitro diagnostics.