High-Efficiency Detection of Total-PSA and Free-PSA in Whole Blood by Microfluidic Chip Integrated with Electromagnetic Co-Preprocessing

Microfluidic chip analytical technology based on micronanotechnology has shown unique advantages in efficient detection of biochemical samples. Integrating micronanostructures, preprocessing, derivatives, and detection units on a chip can realize more efficient detection. In this paper, a multifunctional microfluidic chip integrated with electromagnetic copreprocessing and fluorescence sensing was designed and developed for detecting trace cancer markers total prostate-specific antigen (t-PSA) and free prostate-specific antigen (f-PSA) in whole blood samples. The copreprocessing mode included dielectrophoresis (DEP) separation and magnetic bead enrichment. Blood cells were collected and excluded from the microfluidic chip by the DEP force generated by the inverted V-shaped interdigital array electrodes, achieving a 98% separation efficiency. Simultaneously, severe interference of blood cells in the subsequent magnetic bead enrichment and fluorescence detection could be avoided. The enrichment module consisted of the immunomagnetic bead Fe₃O₄@PEI@Au/Antibody/BSA and the permanent magnet achieved a high enrichment efficiency of 694 times for t-PSA and f-PSA. An "off-on" fluorescence sensing strategy was proposed to detect t-PSA and f-PSA sensitively and rapidly. Furthermore, an on-chip method for quantitative determination of t-PSA and f-PSA in the samples of whole blood was developed. The detection limits were 100 and 500 fg/mL for t-PSA and f-PSA, respectively. The proposed integrated microfluidic chip with the advantages of multifunctional integration, operation simplification, and detection performance exhibited great application prospects for the detection of low-abundance targets in actual biological samples.