Molecularly imprinted ultrafiltration polysulfone membrane with specific nano-cavities for selective separation and enrichment of paclitaxel from plant extract

Abstract

Molecular imprinting technology (MIT) was employed to fabricate polysulfone (PSf) membranes with specific nano-cavities for selective separation and enrichment of paclitaxel from a neat solution and also from yew tree extract. Polymer/template ratio, feed concentration, and the template extractor solvent were optimized. In accordance with the paclitaxel molecular dimension, the specific nano-cavities size was predicted to be 2.18 × 1.16 nm. The membranes were characterized in terms of pure water flux, molecular weight cut-off (MWCO), adsorption and diffusion, porosity, contact angle, and fouling. The results revealed that water flux through the molecularly imprinted membrane (MiM) is slightly less than that for the non-imprinted membrane (NiM), although the other properties relatively enhanced. For an in-depth understanding of the separation performance, the optimized membrane was analyzed by Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS). ATR-FTIR spectra and SEM images showed no significant difference between the imprinted and non-imprinted membranes, while DRS spectra revealed a spatial orientation in the polymer chain. At the optimum condition (paclitaxel concentration in the dope solution =0.5 wt%, feed initial concentration = 20 ppm, and ethanol/water ratio = 50:50 v/v) the MiM exhibited relatively high ability to recognize and separate paclitaxel with imprinting factor of 2.28. The reuse of the MiM up to 3 repeated cycles showed no obvious deterioration in the performance. Furthermore, in a single pass MiM could enrich paclitaxel from a crude yew tree extract, a real or complex solution, up to 48%, which could be quite encouraging from industrial and pharmaceutical points of view.