Guiding point-of-care therapeutic drug monitoring through structure-toxicity principles

A structure-toxicity strategy was employed to generate monoclonal antibodies exhibiting a gradient of affinity corresponding to the toxicity level of biguanides, and an immunochromatographic sensor was established for diabetes drug risk monitoring, enabling a therapeutic drug monitoring function that can accurately identify high-risk biguanides in human serum. The data demonstrated that the H1-induced monoclonal antibody 2G8 was generated with the ability to recognize biguanides according to the toxicity gradient (affinity gradient: phenformin > buformin > moroxydine > metformin), with IC₅₀ values ranging from 0.11 to 3.35 ng mL^-1. Molecular docking revealed that the high affinity was primarily driven by π-π stacking interactions between H: PHE 55/L: PRO 116 residues and biguanides. The developed immunochromatographic sensor for biguanides achieves a cut-off value of 2-500 ng mL^-1 in human serum. Furthermore, based on affinity gradient properties, this sensor can both accurately monitor adherence to metformin therapy in diabetic serum (500-5000 ng mL^-1) and provide rapid visual early warning of metformin overdose (20 µg mL^-1) and trace phenformin toxicity (200 ng mL^-1). Remarkably, the generalizability of the structure-toxicity principle was well validated in structurally complex macrolides. The developed method opened an avenue for coming up with a comprehensive risk management strategy encompassing clinical monitoring and poisoning risk assessment.