Magneto-controlled fluorescent immunosensor for sensitive determination of biomarker via three-dimensional AuNCs/liposome networks

The three-dimensional liposome networks are fabricated and act as signal amplification modules for the fabrication of a magneto-controlled fluorescent immunosensor, in which antibody-conjugated magnetic bead (MB-Ab), streptavidin-biotin recognition and liposome amplification as the triple signal amplification pathway. The Aptamer-Liposome-AuNCs (Apt-Lip-AuNCs) is employed as a fluorescence signal probe, which can release abundant of AuNCs by Triton-X 100 to produce fluorescence emission signal upon being excited at 369 nm. In the presence of target CEA, the labeled anti-CEA on the MB and the immobilized aptamer on the Apt-Lip-AuNCs sandwich the target CEA. Upon addition of streptavidin and Biotin-Lip-AuNCs, three-dimensional liposome networks are formed by a streptavidin-biotin reaction due to the capture of streptavidin for Biotin-Lip-AuNCs and the residual biotin site of liposome on the Apt-Lip-AuNCs, thereby increasing the loading capacity of AuNCs. CEA can be linearly assayed in the range from 0.05 ng mL −1 to 40 ng mL −1 with a detection limit of 13.2 pg mL −1 (3 σ/K ). It provided a concise sensing platform for CEA determination and showed a great potential application for on-site testing in early clinical diagnosis.