8-Quinolineboronic acid as a potential phosphorescent molecular switch for the determination of alpha-fetoprotein variant for the prediction of primary hepatocellular carcinoma

8-Quinolineboronic acid phosphorescent molecular switch (8-QBA-PMS) in the “off” state emitted weak room temperature phosphorescence (RTP) of 8-QBA on the acetylcellulose membrane (ACM) with the perturbation of Pb2+. When 8-QBA-PMS was used to label concanavalin agglutinin (Con A) to form 8-QBA-PMS-Con A based on the reaction between –OH of 8-QBA-PMS and –COOH of Con A, 8-QBA-PMS turned “on” automatically due to its structure change, and RTP of the system increased 2.7 times. Besides, –NH2 of 8-QBA-PMS-Con A could carry out affinity adsorption (AA) reaction with the –COOH of alpha-fetoprotein variant (AFP-V) to form the product Con A-AFP-V-Con A-8-QBA-PMS containing –NH–CO– bond, causing the RTP of the system to further increase. Moreover, the amount of AFP-V was linear to the ΔIp of the system in the range of 0.012–2.40 (fg spot−1). Thus, a new affinity sensitive adsorption solid substrate room temperature phosphorimetry using 8-QBA-PMS as labelling reagent (8-QBA-PMS-AASSRTP) for the determination of AFP-V was proposed with the detection limit (LD) of 9 × 10−15 g mL−1. It had been used to determine AFP-V in human serum with the results agreeing with enzyme-link immunoassay (ELISA), showing promise for the prediction of PHC due to the intimate association between AFP-V and primary hepatocellular carcinoma (PHC). The mechanism of the promethod was also discussed.