The potential of gene therapy for treating genetic disorders has led to a prolific research activity on the design of safe and efficient gene carrier vectors that compact and protect oligonucleotides and DNA against degradation by serum nucleases. Nonviral vector systems1 are an attractive alternative to viral carriers, retroviruses and adenoviruses, to overcome fundamental problems associated with these systems despite the high delivering efficiency that they exhibit: toxicity, immunogenicity and limitations related with scale-up production

The present technology allows the preparation of amphiphilic PAMAM- based dendrimer  bearing alkyl sulfonyl hydrophobic tails in some of the amino pheripheral groups. These compounds are easily and efficiently prepared by means of the aza-Michael type addition of its primary amino groups to vinylsulfone derivatives as an efficient tool for surface engineering.

Albeit the transfection properties are dependent on the chemical structure of the hydrophobic chain and on the extension of the functionalization of the dendrimers surface, some of these engineered PAMAM-G2 dendrimers are useful vectors with improved transfection properties when compared to unmodified PAMAM-G2 and commercial transfection reagents such as Lipofectamine2000: higher transfection efficiencies, lower cytotoxicity, the capability to maintain their transfection efficiency in the presence of serum and the ability to transfect different eukaryotic cell lines.

The  flexibility of the vinylsulfone based chemistry also allowed the fluorescent labeling of these PAMAM derivatives for the preparation of probes to monitor the endocytic pathway used for successful transfection by the dendrimers.