Pan Chao, Liu Xiaoru, Gong Kai, Mumtaz Fatima, Wang Yanmei
CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China.
J Mater Chem B. 2018 Jan 28;6(4):556-567. doi: 10.1039/c7tb02209c. Epub 2018 Jan 5.
Protein adsorption on interfaces immersed in biological fluids is a prevalent and mostly irreversible phenomenon of great importance and is often uncontrolled. Poly(2-methyl-2-oxazoline) (PMOXA) is shown to possess excellent protein-resistant properties, whereas proteins can be adsorbed deeply inside the swollen brushes of poly(acrylic acid) (PAA). In this work, mixed brushes of PMOXA/PAA were prepared by sequentially grafting amine-terminated PMOXA (PMOXA-NH) and thiol-terminated PAA (PAA-SH) onto poly(dopamine) (PDA)-coated substrates. The constituents of the mixed brushes can be adjusted by changing the grafting time of PMOXA-NH or PAA-SH to the PDA-coated surfaces. PAA chains with different molecular weights in the mixed brushes of PMOXA/PAA were used to investigate the effect of the length of the PAA chains on the surface wetting and protein adsorption on the prepared interfaces. The prepared brushes were rigorously characterized in terms of the surface chemical composition, thickness and hydrophilicity using X-ray photoelectron spectroscopy (XPS), ellipsometry and the static water contact angle (WCA) tests. Protein adsorption/desorption on the brushes were monitored using fluorescence microscopy as well as surface plasmon resonance (SPR) for in situ and real-time measurements. The results demonstrated that the WCA on mixed brushes could be reversibly tuned with the variation of pH and I, the amount of bovine serum albumin (BSA) adsorbed on mixed brushes could be well regulated by the grafting time and the molecular weight of PAA-SH, and the maximal amount (87%) of adsorbed BSA could then be desorbed upon changing pH and I. The highly switchable protein adsorption/desorption properties are therefore a nice combination of the protein-resistance of PMOXA and the salt and pH-sensitivity of PAA.
蛋白质吸附到浸入生物流体中的界面上是一种普遍且大多不可逆的现象，极为重要且常常不受控制。聚（2-甲基-2-恶唑啉）（PMOXA）显示出优异的抗蛋白质性能，而蛋白质可被深深吸附在聚（丙烯酸）（PAA）的溶胀刷内部。在这项工作中，通过将胺基封端的PMOXA（PMOXA-NH）和硫醇封端的PAA（PAA-SH）依次接枝到聚多巴胺（PDA）涂层的基底上，制备了PMOXA/PAA混合刷。通过改变PMOXA-NH或PAA-SH接枝到PDA涂层表面的时间，可以调节混合刷的组成。使用PMOXA/PAA混合刷中不同分子量的PAA链来研究PAA链长度对所制备界面的表面润湿性和蛋白质吸附的影响。使用X射线光电子能谱（XPS）、椭偏仪和静态水接触角（WCA）测试，对所制备的刷在表面化学成分、厚度和亲水性方面进行了严格表征。使用荧光显微镜以及表面等离子体共振（SPR）对刷上的蛋白质吸附/解吸进行监测，以进行原位和实时测量。结果表明，混合刷上的WCA可随pH和离子强度（I）的变化而可逆调节，混合刷上吸附的牛血清白蛋白（BSA）量可通过PAA-SH的接枝时间和分子量得到很好的调控，并且在改变pH和离子强度时，最多87%吸附的BSA可以解吸。因此，高度可切换的蛋白质吸附/解吸特性是PMOXA的抗蛋白质性能与PAA的盐和pH敏感性的良好结合。
