The Z-potential of control OM-pBAE polyplexes having two different homomeric oligopeptides, -CRRR and -CHHH, was roughly 26 mV as previously reported, while OM-pBAEs having single chain of heteromeric oligopeptide show a slightly higher charge, 34-41 mV (Figure ). This increase in the zeta potential of OM-pBAEs bearing a single chain of heteromeric -CRHR oligopeptide is due to the higher R:H ratio, from 60:40 in previous formulations with two different homomeric chains to 66:33 ratio present in the simplified formulation. An increase in arginines, all of which bear a net positive charge due to their high pKa, results in higher overall charge of the polyplexes.