The transfection of the suitable genes into cells is the primary target of gene therapy. Earlier the genes are trasfected by binding with gold nanoparticles and injecting by a transfection gun. Later the electroporation technique is used where the small electric voltage is applied which increases the permeability of the cell which leads to intake of more genes of interest. Recently, the use of magnetic nanoparticles is rapid in studying the gene delivery mechanism for various diseases and various kinds of genes of interest. The delivery of genes has to overcome the barriers of the skin if it is transfected externally or if to the brain it has to cross the blood-brain barrier (BBB) a key rate limiting step in the drug/gene delivery to brain. People employ mostly liposomes for brain drug delivery as they easily pass the BBB. Several researchers are trying to get the correct carrier with proper mechanism to have a successful gene transfection. Companies like Nano Therics (www.nanotherics.com) are provinding various instruments for gene transfection by magnetic nanoparticles.
For the recent news on gene delivery using magnetic nanoparticles, the readers are directed to the following link http://www.sciencedaily.com/releases/2013/05/130530111153.htm. Eventhough the research progresses, still there is much to go.