DNA condensation by pH-responsive polycations
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Updated: Jun 10, 2026

Synthetic Condensates and Cell-Like Architectures from Amphiphilic DNA Nanostructures
Published on: May 31, 2024
Andreia F Jorge1, Rita S Dias, Jorge C Pereira
1Department of Chemistry, Coimbra University, Rua Larga, 3004-535 Coimbra, Portugal.
Abstract:
This work addresses the impact of pH variation on DNA-polyethylenimine (PEI) complex formation, in aqueous solution and at constant ionic strength. An initial potentiometric characterization of the acid-base behavior of PEI is carried out to measure the concentration of ionized species in the relevant systems. The characterization of the DNA-PEI complexes is performed by precipitation assays, agarose gel electrophoresis, photon correlation spectroscopy, and zeta potential analysis. It is observed that the variations on the electrophoretic mobility, size, and electrical properties of complexes display nonmonotonic, nontrivial trends with pH, if the same polycation/polyanion charge ratios are used for different values of pH. It is seen that both linear charge density and the relative number of chains of the condensing agent are important factors governing the condensation behavior. Complexes prepared at pH 4, for example, indicate strong binding and a large mean size, while those prepared at pH 8 are smaller, in a more uniform population. Finally, charge inversion was observed for all studied pH values (even below charge neutralization).
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