Screening of peptide selectively recognizing prostate-specific antigen and its application in detecting total prostate-specific antigen

Prostate specific antigen (PSA) is one of the important indexes of prostate cancer, which is widely used in the early diagnosis and treatment of prostate cancer. In this study, based on pIII phage display library, the biopanning method for PSA was established by optimizing the elution strategy by additional BSA pre-screening and serum interference. After sequencing, seven phage monoclonals were obtained. The binding and specificity of phage monoclonals were identified, of which two PSA-specific phage monoclonals were finally obtained. The phage monoclone expressing peptide TSIANYIGLALR showed the best affinity and specificity against PSA, which was chemically synthesized by linking with GGGGSK-biotin at its C-terminus. By using the explored peptide as recognition probe and the biotin-streptavidin affinity system to amplify the signal, a sandwiched ELISA system was constructed. After optimization of the ELISA conditions, the as-established ELISA is capable of detecting total prostate-specific antigen (tPSA) with the linear range of 0.25-200 ng/mL and the detection limit of 0.18 ng/mL. Further, this method could detect tPSA in real serums accurately. Thus, this work proves that peptides replace recognition antibodies for immunoassay has good prospects.