Molecularly imprinted composite membranes with interleaved imprinted network structure for highly selective separation of acteoside.

Acteoside (ACT) is one of the phenylethanoid glycosides in Cistanche tubulosa. The ACT molecules have high medicinal value, but the content of ACT is scarce. Therefore, it is imperative to develop the ACT-based molecularly imprinted composite membranes (A-MICMs) with highly selective separation of ACT. In this study, the amine-polyhedral oligomeric sesquisiloxanes (NH2-POSS) were uniformly introduced into polydopamine modified polyvinylidene fluoride (pDA@PVDF) membranes to fabricate NH2-POSS-pDA@PVDF. Then, the ACT-imprinted layers were synthesized on the surface of NH2-POSS-pDA@PVDF to obtain A-MICMs. The results showed that the optimal conditions were 180 mg DA, 12 h DA self-polymerization time, 400 mg NH2-POSS and 10 h washing time for the synthesis of A-MICMs. The results of adsorption isotherm experiments showed that there was a single layer adsorbate analyte on the A-MICMs. The results of adsorption kinetic experiments showed that chemisorption mechanism played a major function in the adsorption process of A-MICMs for ACT. The A-MICMs exhibited the maximum rebinding capacity of 98.37 mg⋅g-1, an excellent rebinding selectivity of 4.63, and the permselectivity of 7.02. The same A-MICMs kept 95.99% of the maximum rebinding capacity for ACT after 5 adsorption-desorption cycles. The designed A-MICMs with the interleaved imprinted network structure have a potential to be applied to the highly selective separation of bioactive components from natural products.

Selective identification and separation of ReO4- by biomimetic flexible temperature-sensitive imprinted composite membranes.

A new type of temperature-sensitive imprinted composite membranes(ICMs) was developed. Poly N,N-diethylacrylamide (DEA) blocks, as temperature-sensitive polymer, were grafted onto the substrate of the imprinted polymer separation layer to endow membranes with better adsorption effect. The comprehensive properties of the imprinted composite membranes were adequately tested and evaluated in detail. Results showed that ReO4- -ICMs (Re-ICMs) with temperature-sensitive recognition sites could adjust the structure of the imprinted holes at different temperatures, which presented excellent performance in the selective separation and purification of ReO4-. The prepared Re-ICMs exhibit the maximum adsorption capacity of 0.1639 mmol/g at 35 °C with the equilibrium adsorption time of 2 h. After ten adsorption/desorption cycles, Re-ICMs could still maintain 73.5% of the original adsorption capacity, the separation degree of ReO4-/MnO4- was only reduced from the initial 24.5 to 15.9, and the desorption ratio dropped from 80.4% to 68.4%, indicating that Re-ICMs have excellent adsorption and separation performance and reusability.

Preparation and application of curcumin molecularly imprinted composite membrane based on ATRP technique / 中草药

Objective: To prepare the molecularly imprinted composite membrane of curcumin by the atom transfer radical polymerization (ATRP) technique and develop a method for the separation and enrichment of curcumin in actual samples. Methods Curcumin MIM were prepared by thermal polymerization method using curcumin as template molecule, methylacrylic acid as functional monmers, cuprous chloride as catalyst, pentamethyldiethylenetriamine as ligand, and polyvinylidene fluoride as base membrane. The microstructure of MIM was investigated by SEM. The maximum adsorption and adsorption equilibrium time of MIM were investigated by static and dynamic adsorption experiment, and the selective penetration capacity was studied. The MIM as membrane material of osmotic device combined with HPLC was used for separation, enrichment and determination of curcumin in samples. Results The results showed that the prepared curcumin MIM had a regular distribution of pores and a uniform size. The maximum adsorption capacity was 3.81 mg/g, and the adsorption equilibrium could be achieved in 15 min. In the selective permeation process of ferulic acid, quercetin and curcumin, MIM had a high selective permeability to curcumin. The average recovery rates of curcumin in ginger, turmeric and curry were (94.100 ± 3.952)%, (98.300 ± 3.637)%, and (97.900 ± 3.133)%, respectively. The RSD was less than 4.2%. The limit of detection was 1.76 μg/kg. Conclusion The prepared MIM is a new material for strong selectivity, separation and enrichment of Chinese medicine curcumin with fast adsorption speed. At the same time, it also provides reference for chemical composition research of other Chinese materia medica.