High sensitive detection method for protein by combining the magnetic separation with cation exchange based signal amplification

PSA is a member of low abundance proteins and serves as a critical indicator of the development and therapy efficacy for prostate cancer. In this study, a facile and high sensitive method was developed for serum PSA detection by integrating the immunomagnetic separation and cation exchange based signal amplification. On the basis of nanoparticle preparation and immunoprobe construction, PSA in serum was captured, separated by the immunomagnetic probe and then interacted with the quantum dots (QDs) based immunofluorescence probe; Zn²⁺ inside QDs was replaced by Ag⁺ within seconds, after which fluorescence signal was amplified by Fluozin-3, the Zn²⁺ responsive dye. Under optimized conditions, low detection limit (1.56 pg/mL), wide linear range (1.56–25 ng/mL) and good repeatability (intra-coefficient variation=3.18%) were achieved, which is superior to commercialized ELISA kit. These results demonstrated the potential of our high sensitive method for PSA detection in clinical.