Paratope‐Specific Recognition Biosensing Materials for Real‐Time Monoclonal Antibody Detection and Personalized Therapy

Monoclonal antibody (mAb) therapeutics are cornerstone treatments for cancers, autoimmune diseases, and infections. However, their efficacy is often compromised by anti‐drug antibody (ADA) formation. Accurate and dynamic detection of mAbs and ADAs is essential for early immunogenicity evaluation and individualized dosing. Using the model adalimumab (ADL), we developed a dual biosensing strategy that enables the simultaneous quantification of mAb drugs and ADA. To overcome the lack of paratope‐specific recognition elements in mAb assays, a bidirectional positive/negative phage display screening method based on F(ab′) 2 fragments was established, removing interference from homologous IgG. Using this approach, a specific ADL‐paratope recognition peptide, CP1 , was successfully identified, demonstrating high affinity with K D of 7.84 µM. For ADA recognition, an ADL‐derived single‐chain variable fragment ( c ‐scFv ) was used as an ADA paratope‐targeting unit. CP1 and c ‐scFv were conjugated to AuNPs to construct biosensing materials: CP1.1@AuNPs and c ‐scFv@AuNPs for ADL and ADA detection, respectively, enabling rapid 2‐min quantification that highly correlated with results of ELISA detection ( R 2 = 0.99). These paratope‐specific recognition element‐functionalized biosensors were successfully applied for the real‐time detection of ADL and ADA in 33 patients with ankylosing spondylitis, supporting personalized therapeutic refinement and offering a practical approach toward the precision management of mAb therapies.