Dual-monomer magnetic molecularly imprinted polymer for highly efficient luteolin separation from natural products

A novel dual-monomer magnetic molecularly imprinted polymer (D/L-MMIP) was developed for the selective extraction of luteolin (Lut) by synergistically combining covalent and non-covalent imprinting strategies. The D/L-MMIP was synthesized via free radical polymerization using phenylboronic acid-functionalized Fe 3 O 4 nanoparticles (covalent monomer) and acrylamide (non-covalent monomer). Comprehensive characterization (FT-IR, XRD, SEM, VSM) verified the successful fabrication of D/L-MMIP, confirming its molecularly imprinted structure, spherical morphology, and strong magnetic responsiveness, with Fe 3 O 4 enabling rapid separation (<30 s). The adsorption kinetics reached equilibrium within 120 min at room temperature. Adsorption studies demonstrated pseudo-second-order kinetics (R 2  > 0.99) and Langmuir isotherm behavior (R 2  > 0.99), yielding a maximum adsorption capacity (q max ) of 15.9 mg·g −1 , which was significantly higher than those of non-imprinted (D/L-MNIP, 7.3 mg·g −1 ) and single-monomer MIPs (S/L-MMIP: 4.2 mg·g −1 ; S/L-CMMIP: 7.4 mg·g −1 ). The D/L-MMIP exhibited exceptional selectivity for Lut (imprinting factor = 4.76) over structurally similar flavonoids (quercetin, rutin, hyperoside), with selectivity coefficients (α) of 6.15, 2.64, and 1.53, respectively. The pH-responsive boronic ester bond facilitated efficient template release under acidic conditions (pH ∼ 2.1), while the material maintained 83.5 % of its adsorption capacity after five regeneration cycles. When applied to Lonicera japonica Thunb. extracts, D/L-MMIP enrichment improved Lut purity from 36 % to 60 % (as determined by HPCE), demonstrating its practical applicability. This study provides a sustainable and efficient strategy for the selective separation of bioactive compounds, leveraging the complementary advantages of covalent and non-covalent interactions for enhanced molecular recognition.