TY - JOUR
T1 - Influence of assembling pH on the stability of poly(l-glutamic acid) and poly(l-lysine) multilayers against urea treatment
AU - Zhou, Jie
AU - Wang, Bo
AU - Tong, Weijun
AU - Maltseva, Elena
AU - Zhang, Gang
AU - Krastev, Rumen
AU - Gao, Changyou
AU - Möhwald, Helmuth
AU - Shen, Jiacong
N1 - Funding Information:
We thank Dr. L. Ma and Z.W. Mao for their continuous support and stimulating discussions. This study is financially supported by the Natural Science Foundation of China (20434030), the Major State Basic Research Program of China (2005CB623902) and the National Science Fund for Distinguished Young Scholars of China (50425311).
PY - 2008/4/1
Y1 - 2008/4/1
N2 - Polyelectrolyte multilayers of poly(l-glutamic acid) (PGA) and poly(l-lysine) (PLL) were built up using the layer-by-layer (LbL) technique in low pH (3.6, PM3.6) and in neutral pH (7.4, PM7.4) solutions. The multilayers were then treated with a concentrated urea (one kind of denaturant for proteins and polypeptides) solution (8 M) and rinsed with corresponding buffer. The buildup and treatment processes were investigated by ultraviolet visible spectroscopy and ellipsometry. The surface morphology was observed by scanning force microscopy (SFM). The inner structures were determined by X-ray reflectometry and circular dichroism spectroscopy (CD). An exponential growth of the optical mass and the layer thickness was observed for both PM3.6 and PM7.4. After urea treatment, a significant mass loss for PM3.6 was found, while no mass change was recorded for PM7.4. The dominant driving force for PM7.4 is electrostatic interaction, resulting in multilayers with an abundant β-sheet structure, which has higher stability against urea treatment. By contrast, the dominant driving force for PM3.6 is hydrogen bonding and hydrophobic interaction, which are sensitive to the urea treatment. The mechanism is substantiated by molecular mechanics calculation. This has offered a convenient pathway to mediate the multilayer properties, which is of great importance for potential applications.
AB - Polyelectrolyte multilayers of poly(l-glutamic acid) (PGA) and poly(l-lysine) (PLL) were built up using the layer-by-layer (LbL) technique in low pH (3.6, PM3.6) and in neutral pH (7.4, PM7.4) solutions. The multilayers were then treated with a concentrated urea (one kind of denaturant for proteins and polypeptides) solution (8 M) and rinsed with corresponding buffer. The buildup and treatment processes were investigated by ultraviolet visible spectroscopy and ellipsometry. The surface morphology was observed by scanning force microscopy (SFM). The inner structures were determined by X-ray reflectometry and circular dichroism spectroscopy (CD). An exponential growth of the optical mass and the layer thickness was observed for both PM3.6 and PM7.4. After urea treatment, a significant mass loss for PM3.6 was found, while no mass change was recorded for PM7.4. The dominant driving force for PM7.4 is electrostatic interaction, resulting in multilayers with an abundant β-sheet structure, which has higher stability against urea treatment. By contrast, the dominant driving force for PM3.6 is hydrogen bonding and hydrophobic interaction, which are sensitive to the urea treatment. The mechanism is substantiated by molecular mechanics calculation. This has offered a convenient pathway to mediate the multilayer properties, which is of great importance for potential applications.
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U2 - 10.1016/j.colsurfb.2007.10.017
DO - 10.1016/j.colsurfb.2007.10.017
M3 - Article
C2 - 18068958
AN - SCOPUS:39549093545
SN - 0927-7765
VL - 62
SP - 250
EP - 257
JO - Colloids and Surfaces B: Biointerfaces
JF - Colloids and Surfaces B: Biointerfaces
IS - 2
ER -