茶多酚-介孔纳米氧化锌控释抗氧抗菌配合体的制备与表征

Synthesis and characterization of pH responsive tea polyphenols/mesoporouszinc oxide nano-complex with antioxidant and antibacterial activity

以聚氧乙烯聚氧丙烯醚嵌段共聚物(Poloxamer 188)和蔗糖为双模板剂制备介孔纳米氧化锌,以此为载体搭载天然抗氧抗菌剂茶多酚,制成具有pH响应控释效果的抗氧抗菌活性纳米配合体。并通过X射线衍射仪(XRD)、氮气吸附/脱附、透射电子显微镜(TEM)等对介孔纳米氧化锌进行表征;通过扫描电子显微镜(SEM)、热重分析(TGA)、傅里叶红外光谱分析(FT-IR)、控释性能测试及抗氧抗菌测试等,研究了配合体的性能。结果显示,以硝酸锌为锌源制得的介孔纳米氧化锌载体,比表面积和孔结构均优于醋酸锌为锌源的产物,硝酸锌制备产物的比表面积达80.614 m^(2)/g,平均孔径为7.426 nm,孔容为0.424 cm^(3)/g。所得配合体中茶多酚搭载量可达74.46%~76.28%,同时具有显著的pH控释效应,弱酸条件可以显著提高配合体中茶多酚的释放速度和释放率,在pH=5.5条件下具有最大释放速度和释放率,最大平衡释放率可达90%。在低浓度下配合体具有延迟清除DPPH自由基特点,在较高浓度下对DPPH自由基的清除率优于茶多酚;所制备的介孔纳米氧化锌载体和配合体对大肠埃希氏菌和金黄葡萄球菌均有明显抑制作用。在智能型抗氧抗菌活性包装方面具有较大的应用潜力。

In the present study,an antioxidant and antibacterial nano-complex with pH-sensitive controlled release effect was successfully prepared and achieved the pH-responsive release of tea polyphenols.Mesoporous zinc oxide nanoparticles were first prepared by using polyoxyethylene polyoxypropylene ether block copolymer(Poloxamer 188)and sucrose as double-templates,and characterized by different techniques like X-ray diffraction(XRD),nitrogen adsorption and desorption(BET analysis),transmission electron microscope(TEM),etc.Then the mesoporous zinc oxide nanoparticles with well-defined properties were selected as a nano-carrier.Tea polyphenols were loaded on the carrier to prepared antioxidant and antibacterial activity nano-complex.The properties of the nano-complex were analyzed by scanning electron microscopy(SEM),thermogravimetric analysis(TGA),Fourier transform infrared spectroscopy(FT-IR),controlled release test and antioxidant and antibacterial test.The observed results declared that the specific surface area and pore structure of mesoporous nano-zinc oxide carrier prepared with zinc nitrate as zinc source are superior to that of zinc acetate as zinc source.The specific surface area of the product prepared with zinc nitrate was 80.614 m^(2)/g,the average pore diameter was 7.426 nm,and the pore volume was 0.424 cm^(3)/g.The loading content of tea polyphenols in the nano-complex could reach 74.46%-76.28%,and it had significant pH controlled release effect.Weak acid condition could significantly improve the release rate and ratio of tea polyphenols in the nano-complex.The nano-complex achieved maximum release rate and ratio under the condition of pH=5.5,with maximum equilibrium release rate of 90%.The nano-complex could delay scavenging of DPPH free radicals at low concentrations,while it had a better scavenging effect than tea polyphenols at high concentration.The results of inhibition zone test and minimal inhibitory concentration(MIC)test also proved that the mesoporous zinc oxide nano-carrier and nano-complex both had obvious antibacterial activity against to Escherichia coli and Staphylococcus aureus.The nano-complex has great application potential in intelligent antioxidant and antibacterial packaging.