All samples exhibited rearrangements upon exposure to a more acidic environment leading to more tightly packed polyplexes. The DNA-DNA spacings for these samples were determined to be intermediate between the DNA-DNA spacings observed for samples condensed at pH 7.5 and pH 4. Figure displays the time course for the Bragg spacings for DNA condensed by all three polymers at either pH 7.5, pH 4.0, as well as the pH 7.5-4.0 samples measured at either 1 or 24 h equilibration. All samples showed modest rearrangements to smaller Bragg spacings after 24 h.