Design, characterization, and validation of a high-affinity synthetic peptide as bioreceptor for label-free detection of prostate specific antigen

Panchali Barman; Sheetal Sharma; Shubhi Joshi; Mayank Maan; Shweta Sharma; Avneet Saini

doi:10.1016/j.saa.2025.126531

Design, characterization, and validation of a high-affinity synthetic peptide as bioreceptor for label-free detection of prostate specific antigen

Spectrochim Acta A Mol Biomol Spectrosc. 2025 Dec 15:343:126531. doi: 10.1016/j.saa.2025.126531. Epub 2025 Jun 4.

Authors

Panchali Barman¹, Sheetal Sharma², Shubhi Joshi³, Mayank Maan⁴, Shweta Sharma¹, Avneet Saini⁵

Affiliations

¹ Institute of Forensic Science and Criminology (UIEAST), Panjab University, Chandigarh 160014, India.
² Department of Biophysics, Panjab University, Chandigarh, U.T 160014, India; Department of Biological Systems Engineering, Plaksha University, SAS Nagar, Punjab 140306, India.
³ Department of Biophysics, Panjab University, Chandigarh, U.T 160014, India; University School of Allied Health Sciences, Rayat Bahra University, Mohali, Punjab 140103 India.
⁴ Department of Biophysics, Panjab University, Chandigarh, U.T 160014, India.
⁵ Department of Biophysics, Panjab University, Chandigarh, U.T 160014, India. Electronic address: avneet@pu.ac.in.

PMID: 40505236
DOI: 10.1016/j.saa.2025.126531

Abstract

Prostate-specific antigen (PSA), a serine protease produced by the prostate epithelial cells, is a key biomarker in prostate-associated diseases. While current diagnostic methods to detect prostate abnormalities such as PSA tests, digital rectal exams, prostate biopsies, etc., are widely used, they are often invasive, have poor selectivity and are time-consuming. Thus, an improved and simplified PSA detection strategy is required. In the current study, we report a novel peptide P1 specifically designed to target PSA. Intrinsic tryptophan fluorescence spectroscopy (TFS) was explored to validate the binding affinity between P1 and PSA. This approach, although effortless, has not been widely explored for binding studies. The presence of 7 tryptophan residues in PSA, with 2 of them in its binding site, led us to explore TFS for recognition of PSA-P1 interactions. Four novel synthetic peptide analogues were designed from a PSA-specific monoclonal antibody, with P1 (TFTTYYILDYA) exhibiting the strongest binding affinity towards PSA (-11.8 kcal/mol). Tryptophan Fluorescence spectroscopy (TFS) subsequently validated the strong binding affinity of P1 towards PSA with an apparent dissociation constant (K_D) of 52 nM when PSA was titrated with different concentrations of P1, and a K_D of 0.23 µM when P1 was titrated with varying concentrations of PSA. Secondary structure analysis revealed that P1 adopts a β-sheet conformation and exhibits notable thermal stability, withstanding temperatures as high as 205 °C, which renders it a stable bioreceptor for robust detection of PSA. The results suggest that P1 holds significant potential as a PSA-specific bioreceptor in biosensors. This is the first study of its kind. It ascertains that P1 is a viable, cost-effective, highly stable, robust, and selective peptide with strong potential to be a label-free bioreceptor for recognising PSA in various biological matrices. Its ability to form stable, selective and biocompatible interactions with PSA makes P1 a critical component in developing non-invasive and efficient detection systems.

Keywords: Bioreceptor; Intrinsic tryptophan fluorescence; Molecular docking; Molecular modelling; PSA detection; Peptide; Prostate-specific antigen.

MeSH terms

Amino Acid Sequence
Biosensing Techniques* / methods
Humans
Male
Peptides* / chemical synthesis
Peptides* / chemistry
Peptides* / metabolism
Prostate-Specific Antigen* / analysis
Protein Binding
Spectrometry, Fluorescence
Tryptophan / chemistry

Substances

Prostate-Specific Antigen
Peptides
Tryptophan