Biophysical study of Polyethylenimine-DNA complex used in DNA transfection

Wael Awad mohammed¹*, Mohsen M. Mady¹, Nadia M. El-Guendy², Anwar A. Elsayed¹

E-mail: npm2020@yahoo.com

1- Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt;

2- Cancer Biology Department, National Cancer Institute, Cairo University, Cairo, Egypt.

Success of human gene therapy depends upon the development of delivery vehicles or vectors, which can selectively deliver therapeutic genes to target cells with efficiency and safety. Many cationic polymers have been used to condense DNA by electrostatic interaction into small particles (Polyplex), for protecting the DNA from degradation and enhancing uptake via endocytosis. Polyethylenimine (PEI) appears to be one of the most advanced delivery system that can condense DNA efficiently forming PEI-DNA Polyplex complex. The physicochemical properties of different molecular weights of PEI, such as condensation ability, buffer capacity, time kinetics, FTIR and surface charges of the PEI-DNA complexes may be important factors to obtain a higher transfection efficiency of the polycation vectors. Our intent in this study was to characterize PEI-DNA complexes to see whether these physicochemical properties have any influence on their disposition characteristics and cellular uptake process. We found that PEI-DNA complexes, obtained by the 25 k PEI at N/P ratio > 4, were more stable in the presence of tissue culture medium & serum, and did not dissociate in Nacl easily.

Key words: Polyethylenimine, Polyplex, Polycations, DNA, transfection, gene delivery.

* Corresponding author contact: 74 Sheref street, Helwan,Cairo,Egypt.

Tel.: (202) 25557958; Mob. : (2012) 4234734

E-mail address: npm2020@yahoo.com