Recombinant Peptide Mimetic NanoLuc Tracer for Sensitive Immunodetection of Mycophenolic Acid

Mycophenolic acid (MPA) is an immunosuppressant drug commonly used to prevent organ rejection in transplanted patients. MPA monitoring of great interest due its small therapeutic window. In this work, a phage-displayed peptide library was select cyclic peptides that bind the MPA-specific recombinant antibody fragment (Fab) and mimic behavior MPA. After biopanning, several were isolated tested confirm their epitope-mimicking nature phage-based competitive immunoassays. identifying best mimetic (ACEGLYAHWC with disulfide constrained loop), immunoassay approaches tested, fusion protein containing sequence bioluminescent enzyme, NanoLuc, developed. The enabled direct use as tracer immunoassays without need for secondary antibodies or further labeling. A sensor, using streptavidin-coupled magnetic beads immobilization biotinylated Fab antibody, detection limit 0.26 ng mL–1 IC50 2.9 ± 0.5 mL–1. biosensor showed good selectivity toward applied analysis immunosuppressive clinical samples, both healthy MPA-treated patients, followed by validation liquid chromatography coupled diode array detection.