Fu Najing, Li Liteng, Liu Xiao, Fu Nian, Zhang Chenchen, Hu Liandong, Li Donghao, Tang Baokun, Zhu Tao
College of Pharmaceutical Science, Key Laboratory of Pharmaceutical Quality Control of Hebei Province, Hebei University, Baoding 071002, China.
College of Pharmaceutical Science, Key Laboratory of Pharmaceutical Quality Control of Hebei Province, Hebei University, Baoding 071002, China; Institute of Process Engineering, Chinese Academy of Sciences, Beijing 010190, China.
J Chromatogr A. 2017 Dec 29;1530:23-34. doi: 10.1016/j.chroma.2017.11.011. Epub 2017 Nov 7.
Typically, a target compound is selected as a template for a molecularly imprinted polymer (MIP); however, some target compounds are not suitable as templates because of their poor solubility. Using the tailoring properties of a deep eutectic solvent (DES), the insoluble target compound caffeic acid was transformed into a ternary choline chloride-caffeic acid-ethylene glycol (ChCl-CA-EG) DES, which was then employed as a template to prepare MIPs. The ternary DES-based MIPs were characterized by Fourier transform infrared spectroscopy, elemental analysis, scanning electron microscopy, and atomic force microscopy. The effects of time, temperature, ionic strength, and pH on the recognition processes for four polyphenols (caffeic acid, protocatechuic acid, catechin, and epicatechin) by 13 ChCl-CA-EG ternary DES-based MIPs was investigated using high-performance liquid chromatography. The recognition specificity of the MIPs for CA was significantly better than that for the other polyphenols, and the MIPs exhibited obvious characteristics of chromatographic packing materials. In addition, the recognition processes mainly followed a second-order kinetics model and the Freundlich isotherm model, which together indicated that the MIPs mainly recognized the polyphenols by chemical interactions including ion exchange, electron exchange, and new bond formation. Furthermore, the specific recognition ability of the MIPs for polyphenols, which was better than those of C, C, or non-molecularly imprinted polymer adsorbents, was successfully applied to the recognition of polyphenols in a Radix asteris sample. The transformation of an insoluble target compound in a polymeric DES for MIP preparation and recognition is a novel and feasible strategy suitable for use in further MIP research developments.
通常，目标化合物被选作分子印迹聚合物（MIP）的模板；然而，一些目标化合物由于其溶解性差而不适合作为模板。利用深共熔溶剂（DES）的剪裁特性，将不溶性目标化合物咖啡酸转化为三元氯化胆碱 - 咖啡酸 - 乙二醇（ChCl - CA - EG）DES，然后将其用作模板来制备MIP。通过傅里叶变换红外光谱、元素分析、扫描电子显微镜和原子力显微镜对基于三元DES的MIP进行了表征。使用高效液相色谱研究了时间、温度、离子强度和pH对13种基于ChCl - CA - EG三元DES的MIP对四种多酚（咖啡酸、原儿茶酸、儿茶素和表儿茶素）识别过程的影响。MIP对CA的识别特异性明显优于其他多酚，并且MIP表现出明显的色谱填料特征。此外，识别过程主要遵循二级动力学模型和弗伦德里希等温线模型，这共同表明MIP主要通过包括离子交换、电子交换和新键形成在内的化学相互作用来识别多酚。此外，MIP对多酚的特异性识别能力优于C、C或非分子印迹聚合物吸附剂，已成功应用于紫菀样品中多酚的识别。在用于MIP制备和识别的聚合物DES中转化不溶性目标化合物是一种新颖且可行的策略，适用于进一步的MIP研究发展。
