aPhysics Department and Shanghai Key Laboratory for Functional Magnetic Resonance Imaging, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, PR China
Abstract:
Solid-state 1H wide-line and 31P magic angle spinning NMR were applied to a series of PEI(polyethylenimine)/DNA complexes. The experimental results revealed that the higher the nitrogen/phosphorus (N/P) molar ratio is, the more phosphorus atoms of DNA are engaged in the electrostatic interaction with PEI. 1H spin–diffusion experiments manifested that the aggregation degree of DNA in the complexes decreases greatly when N/P ratio increases from 0.5 to 3 and changes only slightly with further increase of N/P ratio, indicating that DNA disperses in the matrix of PEI on the molecular level at higher N/P ratio.