聚多巴胺表面修饰毛细管电色谱的研究进展

Advances in polydopamine surface modification for capillary electrochromatography

毛细管电泳(CE)具有分离时间短、分离效率高、样品消耗量低等优点,在分离分析领域有着重要应用。原始的未修饰熔融石英毛细管只能提供阴极流向的电渗流和单一的电泳分离机制,分离性能有限,重复性较差,不能满足各类复杂样品体系尤其是中性和手性样品的分离需求。因此,有必要在CE中引入各类毛细管修饰策略,以拓展其实际应用潜力。贻贝仿生聚多巴胺(PDA)及其衍生材料因其简便易行的制备过程、优异的表面黏附性、良好的生物相容性、较强的二次反应活性和化学稳定性等优点,在催化、传感、水处理、样品前处理、生物医药以及CE分离等领域得到了广泛应用。PDA涂层的制备过程与物理吸附涂层一样简便,而表面黏附涂层的稳定性又可与共价键合涂层相媲美,因此非常适用于石英毛细管柱的修饰。更重要的是,PDA涂层较强的二次反应活性使其可作为反应平台进行灵活多样的二次表面修饰,便于构建多功能PDA涂层毛细管电色谱(CEC)固定相。基于这些突出优点,PDA涂层材料在CEC中的巨大应用价值逐渐得到了研究者们的广泛关注。该文首先对近3年有关PDA形成机理及PDA快速沉积表面化学的最新研究进展进行了总结,在此基础上综述了近10年PDA涂层材料在开管毛细管电色谱(OT-CEC)和毛细管电色谱整体柱中的最新应用。此外,还对PDA涂层材料在CEC中的发展方向进行了展望。

Capillary electrophoresis(CE)has a wide range of applications in analytical fields due to its advantages of low sample consumption,short separation time,and high separation efficiency.The cathodic electroosmotic flow(EOF)and single electrophoretic separation mechanism are not optimal for many CE applications.Hence,the use of an unmodified fused-silica capillary leads to insufficient separation performance that cannot meet the requirements for various complex sample systems,especially neutral and chiral compounds.Therefore,it is necessary to introduce various capillary modification strategies in CE so that its potential for practical application can be expanded.Mussel-inspired polydopamine(PDA)and PDA-derived coating materials have fascinating advantages such as simple surface coating procedures,strong surface adhesiveness,good chemical stability,latent reactivity with many functionalized molecules,and good biocompatibility.Thus,they have been widely utilized in different research fields,including catalysis,sensing,water treatment,sample pretreatment,biomedicine,chromatographic separation,and CE.The preparation of PDA coatings is simple as it involves physical adsorption,and the obtained surface adhesive coatings possess good stability similar to covalently bonded coatings.Therefore,PDA and PDA-derived coatings are well suited for the modification of fused-silica capillaries.More importantly,the PDA coating can be utilized as an intermediate reaction platform for diverse subsequent surface modification because of its strong surface adhesive property and strong latent reactivity with many functionalized molecules(such as polymers,proteins,and nanomaterials).Consequently,various chromatographic retention mechanisms can be introduced on the inner wall of the capillary,thereby contributing to the fabrication of multi-functional PDA-based stationary phases for CEC.Owing to these outstanding advantages,researchers are paying increasing attention to the great application potential of PDA and PDA-derived coatings in CEC.In this paper,recent advances in the methods for preparing PDA coatings,especially the recently developed fabrication strategies and various applications of PDA-modified silica capillary in open tubular-capillary electrochromatography(OT-CEC)and capillary electrochromatography monolithic columns,are summarized and discussed.Furthermore,the application prospects of PDA-based coating materials in CEC are prospected in this review.Although PDA and PDA-derived coating materials are seeing widespread utilization in field of CEC,researchers have still not reached a definite conclusion regarding the PDA formation and coating mechanisms,and further investigation is needed in this direction.The PDA coatings formed using existing methods are generally thin.In the early stage,many studies adopted the strategy of repeated coating to improve the coating effect of PDA in capillaries,but this method was found to be time-consuming and less efficient.In order to improve the preparation efficiency of PDA-modified CEC columns,many researchers have focused on fast deposition induced by a strong oxidant to obtain PDA-coated columns.However,the controllability of the PDA coating obtained by this method is poor.Thus,it is necessary to further explore new preparation strategies for PDA-coated CEC capillaries with better reproducibility and stronger operability.On the other hand,although a strategy for directly synthesizing functional PDA-coated CEC columns in the organic phase has been proposed,its application potential in CEC remains to be further explored.In addition,the PDA coating itself has poor porosity and a small specific surface area,which may be significantly improved by modifying the coating on the porous monolithic column surface.However,there has been limited research on the use of PDA coatings in monolithic columns,and their application potential remains to be expanded.With in-depth research into the formation mechanism and preparation methodologies of PDA coatings,PDA,which is a highly malleable biomimetic material,will play a more important role in advances in the fields of CE and CEC.