Completion of human genome project has generated a wealth of information that help in finding out new therapeutic targets. Nucleic acids play the role of new drug for the diseases,of which a genetic basic is known. Thus gene delivery could be exploited to correct missing gene,replace defective gene,or down-regulate aberrant gene expressions. Efficient delivery of nucleic acids into target cell however, continues to be a major impediment for the success of gene therapy.There are mainly two classes of vehicles for gene delivery viral and nonviral vectors.Viral vectors,however,suffer from major disadvantages like adverse immunogenic reaction, insertional mutagenesis, and sometimes fatal toxicity that limit their use in clinical trials. Nonviral vectors, on the other hand, consist of positively charged polymers peptides,or lipids that form self-assemblies with dna.While these non viral vector have the advantages of high dna. carrying capacity, ease of preparation,and lower immunogenicity and cytotoxicity,many of them are not nearly as efficient as viral vectors
Since the discovery by Felgner, many liposomal gene delivery reagents have been developed, Various modifications at the level of polar headgroup, chain-backbone linkage region,and the hydrocarbon chain or hydrophobic parts have been shown to significantly influence the efficacies of liposomal gene delivery system We have demonstrated the advantage of the ether linkage on the modulation of the gene transfection efficiencies of cholesterol based cationic lipids Gimini lipids typically possess two polar head groups and four long aliphatic chains, linked by either a rigid or flexible spacer.
Aggregation properties of the membranes strongly depend on the nature and length of the spacer between the headgroups.
Enhanced gene transfection properties of cholesterol based gemini lipids had also been reported recently