Targeted Biocatalyst Design for Asymmetric Citalopram Conversion in a Membrane Reactor

Objective: This study aimed to develop a stable and active biocatalytic system for enzyme immobilization, utilizing an electrospun support doped with a metal-organic framework (MOF) and supplemented with an ionic liquid as a lipase stabilizer and activity enhancer. Methodology: The system was applied for an efficient and enantioselective resolution of racemic citalopram. Key parameters, including MOF concentration, electrospinning and immobilization conditions, ionic liquid selection, and reaction time, were optimized to enhance biocatalyst performance. Results: The optimal immobilization time was determined to be 24 h, achieving 52% immobilization efficiency and 100% activity recovery. The resulting biocatalytic system HIGH PVC-MOF-lip-CA exhibited superior storage stability, retaining 80% of its initial activity, a 75% improvement over the free enzyme. In the resolution of citalopram, the system achieved 96% conversion of S-citalopram within 24 h, with the enantiomeric excess of 93% in favor of the S-ester over the R-ester. These findings demonstrate the system's potential for efficient and stereoselective biocatalytic applications.