Lipoplex Assembly Visualized by Atomic Force Microscopy

Abstract

Publisher Summary This chapter discusses the experimental approaches to deliver DNA into eukaryotic cells, a process also known as “transfection.” The purpose of such applications may range from substituting malfunctioning genes in cells to expressing novel genes for fundamental cell biological investigations. The development of an appropriate vehicle for the effective (intra-) cellular delivery of the gene(s) of interest has represented a major challenge. The chapter also focuses on the application of atomic force microscopy as a useful tool in the characterization of gene complexes composed of plasmid DNA and cationic lipids. Because of their positive charge, cationic lipids interact readily with the negatively charged DNA, resulting in the assembly of the so-called lipoplexes. When added to cells in culture, these complexes can be internalized, release their DNA, and, eventually, the genes encoded by the DNA are expressed. Hundreds of different cationic amphiphiles have been synthesized. Some important biophysical parameters of the cationic lipids that may drive distinct steps in the overall transfection process are gradually revealed, and many others remain to be determined. Atomic force microscopy (AFM) offers such possibilities. The application of this versatile technique in studies involving the characterization of the lipoplex assembly is described in the chapter.