Green Synthesis of Zwitterionic–Cyclodextrin Hybrid Polymer for Efficient Extraction of Polypeptides: Combination of Instrumental Analysis and DFT Calculation

Adhering to the principles of green analytical chemistry (GAC) is crucial for advancing sample pretreatment. In this work, we developed a green in-tube solid-phase microextraction (IT-SPME) material utilizing non-toxic cyclodextrin and zwitterionic polymers as co-functioning monomers. The hybrid monolithic material was synthesized within 38 min via an efficient epoxy ring-opening reaction and free radical polymerization. Comprehensive characterization confirmed a rigid framework with strong anti-swelling properties, good permeability, and high enrichment efficiency on the polymers. When coupled with HPLC-UV, the optimized IT-SPME method enabled highly sensitive detection of polypeptides (vancomycin and teicoplanin) in aqueous matrices, achieving detection limits as low as 15.0-20.0 μg L^-1, a wide linear range (60-800 μg L^-1, R² > 0.99), and good precision (RSDs = 5.9-8.2%). The prepared material demonstrated remarkable performance in real complex water samples, achieving recovery rates of up to 95.4%. Density functional theory (DFT) calculations indicated that the adsorption mechanism primarily involves hydrogen bonding and electrostatic interactions. This study presents an effective approach for the development of green chemical synthesis of extraction materials and offers a sustainable platform for monitoring trace contaminants in environmental waters.