Lee Hwankyu
Department of Chemical Engineering, Dankook University, Yongin, 448-701, South Korea.
J Mol Graph Model. 2017 Aug;75:1-8. doi: 10.1016/j.jmgm.2017.04.003. Epub 2017 Apr 28.
Single-walled carbon nanotubes (SWCNTs) covalently functionalized or noncovalently coated with polyethylene glycol (PEG) of different sizes (M=2000 and 5000) and grafting densities (5-16 PEGs per SWCNT) are simulated with human fibrinogen (HFG) and serum albumin (HSA). Proteins migrate toward the SWCNT, but their adsorption extents differ. The extent of the HFG-SWCNT binding decreases with increasing PEG size and grafting density because PEGs more completely cover SWCNTs and thus block hydrophobic interactions between HFGs and SWCNTs, which occurs on PEG-functionalized SWCNTs but not on PEG-coated ones. In particular, the HFG-SWCNT binding significantly decreases in the transition region of PEG conformation from mushroom to brush, where PEGs extend like brushes as described in the Alexander-de Gennes theory. While the HFG adsorption is modulated by PEG conformation, the HSA adsorption is much weaker and less influenced by PEG, because spherical HSAs can bind to the restricted area of the SWCNT and thus cannot bind to the SWCNT as tightly as do linear HFGs. These findings agree with experiments showing less adsorption of proteins on the SWCNT functionalized with larger and more PEGs, and support experimental suggestions regarding the dependence of protein adsorption on protein shape and the mushroom-brush transition of PEG conformation.
对用不同尺寸（M = 2000和5000）和接枝密度（每个单壁碳纳米管有5 - 16个聚乙二醇）的聚乙二醇（PEG）共价功能化或非共价包覆的单壁碳纳米管（SWCNT）与人类纤维蛋白原（HFG）和血清白蛋白（HSA）进行了模拟。蛋白质向SWCNT迁移，但其吸附程度不同。HFG - SWCNT结合程度随PEG尺寸和接枝密度的增加而降低，因为PEG更完全地覆盖了SWCNT，从而阻断了HFG与SWCNT之间的疏水相互作用，这种相互作用发生在PEG功能化的SWCNT上，而不是PEG包覆的SWCNT上。特别是，在PEG构象从蘑菇状到刷状的转变区域，HFG - SWCNT结合显著降低，在该区域PEG如亚历山大 - 德热纳理论中所述像刷子一样伸展。虽然HFG的吸附受PEG构象调节，但HSA的吸附要弱得多，且受PEG的影响较小，因为球形的HSA只能结合到SWCNT的受限区域，因此不能像线性的HFG那样紧密地结合到SWCNT上。这些发现与实验结果一致，即蛋白质在功能化有更大和更多PEG的SWCNT上的吸附较少，并支持了关于蛋白质吸附对蛋白质形状的依赖性以及PEG构象的蘑菇 - 刷状转变的实验建议。
