biosensors Article A Rapid Immunochromatographic Method Based on a Secondary Antibody-Labelled Magnetic Nanoprobe for the Detection of Hepatitis B preS2 Surface Antigen Yangyang Cai 1,2,3, Jun Yan 1,2,3, Li Zhu 4, Hengliang Wang 4 and Ying Lu 1,2,3,* 1 College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China;
[email protected] (Y.C.);
[email protected] (J.Y.) 2 Laboratory of Quality & Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai 201306, China 3 Shanghai Engineering Research Center of Aquatic-Product Processing and Preservation, Shanghai 201306, China 4 Beijing Institute of Biotechnology, Beijing 100071, China;
[email protected] (L.Z.);
[email protected] (H.W.) * Correspondence:
[email protected]; Tel.: +86-021-6190-0503 Received: 24 September 2020; Accepted: 27 October 2020; Published: 31 October 2020 Abstract: Hepatitis B is a globally prevalent viral infectious disease caused by the hepatitis B virus (HBV). In this study, an immunochromatographic assay (ICA) for the rapid detection of hepatitis B preS2 antigen (preS2Ag) was established. The magnetic nanoparticles (MNPs) indirectly labelled with goat anti-mouse (GAM) secondary antibody were applied as a nanoprobe for free preS2 antibody (preS2Ab) capturing and signal amplification. By employing sample pre-incubation processing as well, preS2Ag-preS2Ab was sufficiently caught by the GAM-MNPs probe in 5 min. A qualitative sensitivity of 625 ng/mL was obtained by naked-eye observation within 15–20 min. A standard curve (0–5000 ng/mL) was established, with a quantitative limit of detection (LOD) of 3.6 ng/mL, based on the stability and penetrability of the magnetic signal characteristics.