Click-imprinted furfuryl-modified poly(divinylbenzene-maleic anhydride-styrene) for (+)-tramadol recognition

This study presents the successful synthesis and application of a novel enantioselective polymeric sorbent, (+)-TM-P, designed for the stereoselective separation of tramadol (TM) enantiomers. TM primarily exists as dextro (+) and levo (-) enantiomers, and effective separation is crucial for its pharmacological efficacy. The sorbent is based on a polymer composed of poly(divinylbenzene-maleic anhydride -styrene) (CPMA), synthesized through suspension polymerization to form microparticles. The process involves the interaction of the anhydride rings in CPMA with furfurylamine (Fu-NH2), resulting in a polymer (Fu -P) that can adsorb the cationic (+)-TM. Post-crosslinking of these particles is achieved using bis(maleimido)ethane (BME) as a dienophile crosslinker, which reacts with the furan units through Diels-Alder cycloaddition. The (+)-TM is subsequently eluted using an acidic solution, creating stereo-selective cavities in the (+)-TM-P that can selectively rebind (+)-TM. The polymers were characterized by elemental analysis, FTIR, and 13C NMR, while SEM was employed to examine their morphologies. The (+)-TM-P demonstrated a maximum adsorption capacity of 250 mg/g at an optimal pH of 8 and was effective in separating the TM racemate. The enantiomeric excess (ee) values observed were 98 % for (-)-TM during the loading phase and 93 % for (+)-TM during recovery.