Controllable synthesis of dual-functionalized magnetic microporous organic network for effective extraction of...

Magnetic microporous organic network (MMON) materials have attracted extensive attention in sample pretreatment for their excellent adsorption performance and rapid magnetic separation. In this study, a series of novel core-shell structured MMON materials were synthesized by selecting two types of monomers and adjusting the molar ratio of monomers to magnetic spheres. Through pore structure design and theoretical calculations, the molecular sizes of two steroid hormones (progesterone and 17α-hydroxyprogesterone) were determined to be approximately 1.04-1.12 nm, while the pore size of C3C4-type MMON was approximately 1.47 nm, whose suitable pore size enabled efficient adsorption of the target analytes. Furthermore, the amino-carboxyl dual-functionalized magnetic microporous organic network (C3C4-NH₂-COOH) was chosen as an effective adsorbent and exhibited rapid magnetic response, good thermal and chemical stability. Under the optimal conditions, the developed MSPE-UPLC-MS/MS method offered a low detection limit (0.5 pg mL^-1), a wide linear range (1.0-1000.0 pg mL^-1) and a rapid pretreatment process (less than 25 min). The method was successfully applied to the enrichment and determination of trace progesterone and 17α-hydroxyprogesterone in complex samples, with concentrations ranging from 0.062 to 19.19 ng mL^-1 in serum and from 0.83 to 2.67 ng mL^-1 in milk. Combined with density functional theory calculations and instrumental characterization, hydrogen bonding, π-π and hydrophobic interactions were involved in the extraction mechanism. This study achieved controllable synthesis of MMONs by regulating their pore size, shell thickness, and functional groups. Furthermore, it expanded the application of MMONs as adsorbents in the fields of food safety and early disease diagnosis.