A novel solid-phase extraction approach based on π-conjugated polymer-functionalized mesoporous silica nanoparticles...

A new class of π-conjugated polymer-functionalized porous silica adsorbents, including a non-carbonized material (SiO₂@π-CP) and its carbonized derivative (SiO₂@C-π-CP), was developed through a simple, low-cost synthetic strategy. For the first time, these materials were applied as solid-phase extraction (SPE) sorbents for selective purification of four isoquinoline alkaloids, magnoflorine, laurifoline, lindoldhamine and N-methyldomesticinium, from Cinnamomum camphora seed kernels (CCSK). The integration of π-conjugated polymers with porous silica created abundant adsorption sites, enabling synergistic π-π, electrostatic and hydrogen-bonding interactions, and thus significantly enhancing CCSK alkaloid affinity. Comprehensive characterization confirmed successful functionalization and structural stability. Under optimized static conditions, SiO₂@π-CP and SiO₂@C-π-CP exhibited high adsorption capacities of 68.57 and 97.83 mg g⁻¹, respectively, for total CCSK alkaloids, with adsorption behavior well described by pseudo-second-order kinetic and the Freundlich isotherm. Notably, carbonization significantly improved adsorption performance, chemical robustness, and reusability, with both materials maintaining high efficiency after eight adsorption-desorption cycles. Furthermore, SiO₂@C-π-CP was successfully implemented as a dynamic SPE sorbent, with column adsorption behavior accurately predicted by Adams-Bohart, Thomas, Yoon-Nelson, and BDST models, providing a practical basis for scale-up. Following SPE purification, the purity of CCSK alkaloid increased from 32.97% to 61.59%, with a yield of 73.54%. This work introduces a novel π-conjugated polymer-based SPE platform that combines high selectivity, robustness and scalability, offering a promising strategy for efficient plant alkaloids purification.