Biochar-based surface molecularly imprinted polymers for selective separation of camptothecin

Camptothecin (CPT), a pharmacologically important indole alkaloid, requires efficient and selective separation for pharmaceutical applications. In this study, a novel biochar-based surface molecularly imprinted polymer (CPT/BC-SMIP) was successfully synthesized via optimized free radical polymerization, combining the high surface area, excellent adsorption capacity, and environmental friendliness of biochar with the specificity of surface molecular imprinting technology. Characterization results confirm the formation of well-defined imprinting cavities on the CPT/BC-SMIPs, which exhibit excellent molecular recognition and thermal stability. Adsorption studies reveal that CPT adsorption adheres to pseudo-second-order kinetics, achieving equilibrium within 40 min at 298.15 K, with a maximum adsorption capacity of 82.37 mg·g −1 . Notably, the material maintains over 89 % of its initial adsorption capacity after six consecutive adsorption-desorption cycles, demonstrating outstanding reusability. Selectivity experiments validate the superior recognition capability of CPT/BC-SMIPs for CPT, with an imprinting factor of 2.51, while selectivity factors for structural analogs (10-HCPT, 7-ECPT, EVO, and BBR) are recorded at 2.29, 2.32, 2.87, and 2.81, respectively. In practical applications, the material effectively isolates CPT from Camptotheca fruit extracts, achieving recovery rates between 100.25 % and 107.75 %, with relative standard deviations below 3.24 %, indicating promising practical utility. Overall, this study provides a novel approach for the efficient separation and purification of bioactive compounds from natural products and underscores the promising application of CPT/BC-SMIPs in pharmaceutical separation processes. The material's superior adsorption capacity, selectivity, and stability position it as a strong candidate for industrial-scale CPT purification.