<i>N</i>-(4-Aminobutyl)-<i>N</i>-ethylisopropanol and Co<sup>2+</sup> Dual-Functionalized Core–Shell Fe<sub>3</sub>O<sub>4</sub>@Au/Ag Magnetic Nanomaterials with Strong and Stable Chemiluminescence for a Label-Free Exosome Immunosensor
Manli Wang, Jiangnan Shu, Shanshan Wang, Aihua Lyu, Yisha Wang, Dabing Huang, Hua Cui
Abstract
Recently, magnetic beads (MBs) are moving toward chemiluminescence (CL) functional magnetic nanomaterials with a great potential for constructing label-free immunosensors. However, most of the CL-functionalized MBs suffer from scarce binding sites, easy aggregation, and leakage of CL reagents, which will ultimately affect the analytical performance of immunosensors. Herein, by using core–shell Fe 3 O 4 @Au/Ag magnetic nanomaterials as a nanoplatform, a novel N -(4-aminobutyl)- N -ethylisopropanol (ABEI) and Co 2+ dual-functionalized magnetic nanomaterial, namely, Fe 3 O 4 @Au/Ag/ABEI/Co 2+, with strong and stable CL emission was successfully synthesized. Its CL intensity was 36 and 3.5 times higher than that of MB@ABEI-Au/Co 2+ and ABEI and Co 2+ dual-functionalized chemiluminescent MBs previously reported by our group, respectively. It was found that the excellent CL performance of Fe 3 O 4 @Au/Ag/ABEI/Co 2+ could be attributed to the enrichment effect of the Au/Ag shell and the synergistic enhance effect of the Au/Ag shell and Co 2+ . A related CL mechanism has been proposed. Afterward, based on the intense and stable CL emission of Fe 3 O 4 @Au/Ag/ABEI/Co 2+, a sensitive and effective label-free CL immunosensor for exosome detection was established. It exhibited excellent analytical performance with a wide detection range of 3.1 × 10 3 to 3.1 × 10 8 particles/mL and a low detection limit of 2.1 × 10 3 particles/mL, which were better than the vast majority of the reported CL immunosensors. Moreover, the proposed label-free CL immunosensor was successfully used to detect exosomes in human serum samples and enabled us to distinguish healthy persons and lung cancer patients. It has the potential to be a powerful tool for exosome study and early cancer diagnosis.