Dutta Amit K, Nayak Arpan, Belfort Georges
Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA.
J Colloid Interface Sci. 2008 Aug;324(1-2):55-60. doi: 10.1016/j.jcis.2008.04.065. Epub 2008 May 7.
The real-time changes in viscoelasticity of adsorbed poly(L-lysine) (PLL) and adsorbed histone (lysine rich fraction) due to cross-linking by glutaraldehyde and corresponding release of associated water were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D) and attenuated total reflection Fourier transform infrared spectroscopy (ATR/FTIR). The kinetics of PLL and histone adsorption were measured through changes in mass adsorbed onto a gold-coated quartz surface from changes in frequency and dissipation and using the Voigt viscoelastic model. Prior to cross-linking, the shear viscosity and shear modulus of the adsorbed PLL layer were approximately 3.0 x 10(-3) Pas and approximately 2.5 x 10(5) Pa, respectively, while after cross-linking, they increased to approximately 17.5 x 10(-3) Pas and approximately 2.5 x 10(6) Pa, respectively. For the adsorbed histone layer, shear viscosity and shear modulus increased modestly from approximately 1.3 x 10(-3) to approximately 2.0 x 10(-3) Pas and from approximately 1.2 x 10(4) to approximately 1.6 x 10(4) Pa, respectively. The adsorbed mass estimated from the Sauerbrey equation (perfectly elastic) and the Voigt viscoelastic model differ appreciably prior to cross-linking whereas after cross-linking they converged. This is because trapped water molecules were released during cross-linking. This was confirmed experimentally via ATR/FTIR measurements. The variation in viscoelastic properties increased substantially after cross-linking presumably due to fluctuation of the randomly cross-linked network structure. An increase in fluctuation of the viscoelastic properties and the loss of imbibed water could be used as a signature of the formation of a cross-linked network and the amount of cross-linking, respectively.
使用具有耗散监测功能的石英晶体微天平（QCM-D）和衰减全反射傅里叶变换红外光谱（ATR/FTIR），研究了戊二醛交联导致的吸附聚（L-赖氨酸）（PLL）和吸附组蛋白（富含赖氨酸部分）的粘弹性实时变化以及相关水分的相应释放。通过频率和耗散变化以及使用Voigt粘弹性模型，测量了PLL和组蛋白在金涂层石英表面上吸附质量的变化，以此来测定它们的吸附动力学。交联前，吸附的PLL层的剪切粘度和剪切模量分别约为3.0×10⁻³ Pas和约2.5×10⁵ Pa，而交联后，它们分别增加到约17.5×10⁻³ Pas和约2.5×10⁶ Pa。对于吸附的组蛋白层，剪切粘度和剪切模量分别从约1.3×10⁻³ Pas适度增加到约2.0×10⁻³ Pas，从约1.2×10⁴ Pa增加到约1.6×10⁴ Pa。根据Sauerbrey方程（完全弹性）和Voigt粘弹性模型估算的吸附质量在交联前有明显差异，而交联后它们趋于一致。这是因为交联过程中被困的水分子被释放出来。通过ATR/FTIR测量实验证实了这一点。交联后粘弹性性质的变化大幅增加，可能是由于随机交联网络结构的波动。粘弹性性质波动的增加和吸附水的损失可分别用作交联网络形成和交联量的标志。
