A novel NIR fluorescent probe based on p-mercaptophenylboronic acid-functionalized copper nanoclusters for capmatinib quantification.

Accurate quantification of capmatinib (CAMB) in biological fluids is essential for pharmacokinetic evaluation, dose optimization, and therapeutic monitoring during cancer therapy. In this study, a red-emitting "turn-off" fluorescent probe based on p-mercaptophenylboronic acid-functionalized copper nanoclusters (p-MPBA@CuNCs) was designed and optimized for the highly sensitive and selective detection of CAMB. The fluorescence quenching behavior, governed by a synergistic combination of the inner filter effect (IFE) and static quenching mechanisms, enabled an exceptionally wide linear range (0-370 µM) with a remarkably low detection limit of 1.8 nM. The probe exhibited a rapid response time of 1.5 min and outstanding selectivity over structurally related anticancer drugs and common biological interferents. All analytical validation experiments, including linearity, sensitivity, precision, accuracy, and selectivity, were conducted in accordance with the International Conference on Harmonisation (ICH) guidelines Q2(R1) for analytical method validation. Practical applicability was validated in human serum and urine samples using the standard addition method, achieving recoveries between 98.6% and 104.5% with RSDs below 3.60%. The results showed excellent correlation with HPLC-DAD measurements, confirming the analytical accuracy, precision, and robustness of the proposed p-MPBA@CuNC system for real-sample monitoring of CAMB in clinical samples.