DNA compaction into new DNA vectors based on cyclodextrin polymer: Surface enhanced Raman spectroscopy characterization

• Published in: Biopolymers 2006-04, Vol.81 (5), p.360-370
• Main Authors: Burckbuchler, V., Wintgens, V., Lecomte, S., Percot, A., Leborgne, C., Danos, O., Kichler, A., Amiel, C.
• Format: Article
• Language: English
• Subjects: Animals; Biopolymers - chemistry; Cations; Cell Line; Cell Line, Tumor; CHO Cells; Colloids - chemistry; Cricetinae; cyclodextrin; Cyclodextrins - chemistry; DNA - chemistry; DNA complexes; Electrophoresis, Agar Gel; gene transfer; Genetic Vectors; Humans; Luciferases - metabolism; Magnetic Resonance Spectroscopy; Models, Biological; Models, Chemical; Models, Molecular; Nucleic Acid Conformation; Plasmids - metabolism; polyadenosine; Polymers - chemistry; Spectrum Analysis, Raman - methods; surface enhanced Raman spectroscopy (SERS); Transfection; Ultraviolet Rays
• ISSN: 0006-3525; 1097-0282
• DOI: 10.1002/bip.20428

The ability of DNA to bind polycation yielding polyplexes is widely used in nonviral gene delivery. The aim of the present study was to evaluate the DNA compaction with a new DNA vector using Raman spectroscopy. The polyplexes result from an association of a β‐cyclodextrin polymer (polyβ‐CD), an amphiphilic cationic connector (DC‐Chol or adamantane derivative Ada2), and DNA. The charge of the polymeric vector is effectively controlled by simple addition of cationic connector in the medium. We used surface enhanced Raman spectroscopy (SERS) to characterize this ternary complex, monitoring the accessibility of adenyl residues to silver colloids. The first experiments were performed using model systems based on polyA (polyadenosine monophosphate) well characterized by SERS. This model was then extended to plasmid DNA to study polyβ‐CD/Ada2/DNA and polyβ‐CD/DC‐Chol/DNA polyplexes. The SERS spectra show a decrease of signal intensity when the vector/DNA charge ratio (Z+/−) increases. At the highest ratio (Z+/− = 10) the signal is 6‐fold and 3‐fold less intense than the DNA reference signal for Ada2 and DC‐Chol polyplexes, respectively. Thus adenyl residues have a reduced accessibility as DNA is bound to the vector. Moreover, the SERS intensity variations are in agreement with gel electrophoresis and zeta potential experiments on the same systems. The overall study clearly demonstrates that the cationic charges neutralizing the negative charges of DNA result in the formation of stable polyplexes. In vitro transfection efficiency of those DNA vectors are also presented and compared to the classical DC‐Chol lipoplexes (DC‐Chol/DNA). The results show an increase of the transfection efficiency 2‐fold higher with our vector based on polyβ‐CD. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 360–370, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at [e-mail]