Zhi Keke, Li Zhe, Luo Han, Ding Yitong, Chen Feiyan, Tan Yongxiang, Liu Hongrui
Department of Engineering, China University of Petroleum-Beijing at Karamay, Karamay 834000, China.
State Key Laboratory of Heavy Oil Processing-Karamay Branch, Karamay 834000, China.
Polymers (Basel). 2023 Feb 11;15(4):905. doi: 10.3390/polym15040905.
Quercetin, as one of the most biologically active natural flavonoids, is widely found in various vegetables, fruits and Chinese herbs. In this work, molecularly imprinted polymer (MIP) was synthesized through surface molecular imprinting technology with sol-gel polymerization mechanism on SiO at room temperature using quercetin as the template, SiO as the supporter, 3-aminopropyltriethoxysilane (APTES) as the functional monomer, and tetraethoxysilane (TEOS) as the cross-linker. The prepared MIP was characterized via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption measurements to validate its surface morphology, structure and functionality. SEM images revealed that the morphology of MIP was rough and spherical with the particle size of 260 nm larger than that of the support SiO. In the FTIR spectra of MIP, the band around 1499 cm and 2932 cm were assigned to N-H and C-H groups, respectively. The results indicated that the imprinted polymer layers were grafted on the surface of SiO and the MIP had been successfully prepared. Since the specific surface area and pore volume of MIP were markedly higher than those of NIP and SiO and were 52.10 m g and 0.150 cm g, respectively, it was evident that the imprinting process created corresponding imprinted cavities and porosity. The MIP for adsorbing quercetin was evaluated by static adsorption experiment. The results indicated that the adsorption equilibrium could be reached within 90 min and the maximum adsorption capacity was as high as 35.70 mg/g. The mechanism for adsorption kinetics and isotherm of MIP for quercetin was proved to conform the pseudo-second-order kinetics model (R = 0.9930) and the Freundlich isotherm model (R = 0.9999), respectively, revealing that chemical adsorption and heterogeneous surface with multilayer adsorption dominated. In contrast to non-imprinted polymer (NIP), the MIP demonstrated high selectivity and specific recognition towards quercetin whose selectivity coefficients for quercetin relative to biochanin A were 1.61. Furthermore, the adsorption capacity of MIP can be maintaining above 90% after five regeneration cycles, indicating brilliant reusability and potential application for selective adsorption of quercetin.
槲皮素作为生物活性最强的天然黄酮类化合物之一，广泛存在于各种蔬菜、水果和中草药中。在本研究中，以槲皮素为模板，二氧化硅（SiO）为载体，3-氨丙基三乙氧基硅烷（APTES）为功能单体，正硅酸乙酯（TEOS）为交联剂，通过室温下溶胶-凝胶聚合机制的表面分子印迹技术合成了分子印迹聚合物（MIP）。通过扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT-IR）和氮吸附测量对制备的MIP进行表征，以验证其表面形态、结构和功能。SEM图像显示，MIP的形态粗糙且呈球形，粒径比载体SiO大260nm。在MIP的FTIR光谱中，1499cm和2932cm附近的谱带分别归属于N-H和C-H基团。结果表明，印迹聚合物层接枝在SiO表面，成功制备了MIP。由于MIP的比表面积和孔体积明显高于非印迹聚合物（NIP）和SiO，分别为52.10m²/g和0.150cm³/g，显然印迹过程产生了相应的印迹空腔和孔隙率。通过静态吸附实验对吸附槲皮素的MIP进行了评价。结果表明，90min内可达到吸附平衡，最大吸附容量高达35.70mg/g。MIP对槲皮素的吸附动力学和等温线机制分别被证明符合准二级动力学模型（R² = 0.9930）和Freundlich等温线模型（R² = 0.9999），表明化学吸附和多层吸附的非均相表面起主导作用。与非印迹聚合物（NIP）相比，MIP对槲皮素表现出高选择性和特异性识别，其对槲皮素相对于鹰嘴豆芽素A的选择性系数为1.61。此外，MIP经过五次再生循环后吸附容量可保持在90%以上，表明其具有出色的可重复使用性和选择性吸附槲皮素的潜在应用价值。
