Heterogeneity of Polyelectrolyte Diffusion in Polyelectrolyte-Protein Coacervates: A 1H Pulsed Field Gradient NMR Study

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• 作者：Amrish R. Menjoge ; A. Basak Kayitmazer ; Paul L. Dubin ; Werner Jaeger ; Sergey Vasenkov
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：April 24, 2008
• 年：2008
• 卷：112
• 期：16
• 页码：4961 - 4966
• 全文大小：85K
• 年卷期：v.112,no.16(April 24, 2008)
• ISSN：1520-5207

文摘

Proton pulsed field gradient (PFG) NMR was used to study the diffusion of poly(diallyldimethylammoniumchloride) (PDADMAC) in coacervates formed from this polycation and the protein bovine serum albumin(BSA). Application of high (up to 30 T/m) magnetic field gradients in PFG NMR measurements allowedprobing the diffusion of PDADMAC on a length scale of displacements as small as 100 nm in coacervatesformed at different pH's and ionic strengths, i.e., conditions of varying protein-polycation interaction energy.Studies were carried out for a broad range of diffusion times and corresponding values of the mean squaredisplacements. Several ensembles of PDADMAC polycations with different diffusivities were observed inthe measured range of diffusion times. The existence of these ensembles and the pattern of their changeswith increasing diffusion time support the hypothesis about the microscopic heterogeneity of PDADMAC-BSA coacervates and also provide evidence for the dynamic disintegration and reformation of dense domains.