indicates a decrease in its cellular interaction and uptake. The 6 repeat ER and EK motifs provided half the transfection with respect to the 3 repeat zwitterionic motifs. Hence, the longer zwitterions were used in all subsequent experiments (Figure ). Similar results were obtained for both the ER and EK zwitterionic motifs. However, more reproducible results were obtained with ER sequences. Thus, the ER motif zwitterion was used for most of the work described in the following sections.