Determination of trace α-fetoprotein variant by affinity adsorption solid substrate-room temperature phosphorimetry and its application to the forecast of human diseases

Abstract In the presence of ion perturber LiAc, 4-generation polyamidoamine dendrimers (4G-D) could emit strong and stable room temperature phosphorescence (RTP) signal at λ ex max / λ em max = 511.8 / 675.3 nm on nitrocellulose membrane (NCM), and Triton X-100 could sharply enhance the RTP signal of 4G-D. Triton X-100-4G-D was used to label concanavalin agglutinin (Con A) to get the labeling product Triton X-100-4G-D-Con A. Quantitative specific affinity adsorption (AA) reaction between Triton X-100-4G-D-Con A and α-fetoprotein variant (AFP-V) could be carried out on the surface of NCM, whose product Triton X-100-4G-D-Con A-AFP-V could emit strong and stable RTP and its Δ I p was proportional to the content of AFP-V. According to the facts above, a new affinity adsorption solid substrate-room temperature phosphorimetry (AA-SS-RTP) for the determination of trace AFP-V by Con A labeled with Triton X-100-4G-D was established. Detection limits of this method were 0.23 fg spot −1 (direct method, corresponding concentration: 5.8 × 10 −13  g mL −1 ) and 0.13 fg spot −1 (sandwich method, corresponding concentration: 3.2 × 10 −13  g mL −1 ). It has been successfully applied to determine the content of AFP-V in human serum and forecast human diseases, for its high sensitivity, long RTP lifetime, good repeatability, high accuracy and little background perturbation with λ em max at the long wavelength area. Meanwhile, the mechanism for the determination of trace AFP-V using AA-SS-RTP was also discussed.