Pharmacophore-targeted fluorescence sensing of ibrutinib via Michael addition-induced electron transfer on thiol-functionalized carbon dots.

Ibrutinib (IBR), an irreversible inhibitor of Bruton's tyrosine kinase, is commonly used as a first-line therapy for chronic lymphocytic leukemia (CLL) and various other B-cell cancers. Given its narrow therapeutic window and the clinical necessity of long-term administration, accurate therapeutic drug monitoring of IBR in biological fluids is of paramount importance. Herein, we report a novel fluorometric sensing platform for the selective and sensitive determination of IBR based on thiol-functionalized carbon dots (HS-CDs). The sensing mechanism relies on the specific covalent interaction between the -SH groups on HS-CDs and the electrophilic acrylamide moiety of IBR through a rapid Michael addition reaction, which anchors IBR to the CD surface. This binding modifies the local electronic environment of the carbon dots and promotes efficient electron interaction between the electron-rich nitrogen-containing groups of IBR and the CD fluorophore, collectively leading to a concentration-dependent enhancement of fluorescence. The sensor, under optimized conditions, responded linearly from 1.0 to 30.0 ng mL-1, with a minimum detectable concentration of 0.21 ng mL-1. The practical applicability of the platform was demonstrated through the direct quantification of IBR in human serum samples collected from CLL patients, achieving satisfactory recovery values (97.0-100.2%) with minimal sample preparation. The proposed method has strong potential for routine therapeutic drug monitoring in CLL patients undergoing ibrutinib therapy.