Ultrasensitive analysis of heat shock protein 90α with antibodies orderly arrayed on a novel type of immunoprobe based on magnetic COFs.

The early diagnosis of liver cancer by target biomarkers is of great significance for improving the survival rate of cancer patients. However, it is still a challenging task to sensitively detect circulating protein biomarkers due to decreased binding activity of antibodies originating from uncontrolled orientation of immobilization on the surface of a solid matrix. In this work, a novel immunoaffinity probe, Fe3O4@TpBD-DSS-Ab-MEG, based on magnetic COFs with ordered arrangement of anchored antibodies has been developed and applied for the first time to detection of a cancer biomarker, heat shock protein 90alpha (Hsp90α). The fabricated composites possess favorable features from magnetic cores and COF shells, including strong magnetic responses (7.96 emu g−1), ordered active groups, a large amount of immobilized antibodies (111.7 μg/mg), good solvent and thermal stability. Fe3O4@TpBD-DSS-Ab-MEG demonstrated low detection limit (50 pg/mL), high selectivity (Hsp90α:BSA = 1:1000), desirable repeatability and good stability for Hsp90α immunocapture. Compared with other immunoprobes, our materials showed higher selectivity and sensitivity, which were mainly attributed to regular arrays of surface antibodies. Furthermore, samples containing Hsp90α at the concentration of 1 µg/mL in human plasma were used to test our immunoprobe, and 2 peptides of Hsp90α were successfully observed. The proposed non-invasive immunoassay strategy offers enhanced ability to control the orientation of immobilized antibodies and great promise for accurate analysis of the liver cancer biomarker Hsp90α in a complicated biological matrix. In addition, the facile preparation of magnetic COFs support and the satisfactory analytical performance made the newly developed immunoprobe a potential tool for sensitive detection of other cancer biomarkers in clinical diagnosis.