Other investigations have examined PEI-DNA complexation mechanisms by examining factors such as binding strength, stability, and structure. For example, Ketola et al. used fluorescence spectroscopy to reveal distinct differences in DNA cargo binding for linear and branched PEI (LPEI and BPEI, respectively). Other studies suggest that BPEI offers better DNA protection than LPEI, but lower delivery efficiency . However, these studies do not provide a molecular-level picture of the binding modes or conformational dynamics of LPEI and BPEI polyplexes. Developing this molecular-level understanding is crucial for being able to tune the interactions of polymeric carriers so that they can more robustly accommodate different types of cargo, form more stable polyplexes, offer better cargo protection, or re-lease their cargo more efficiently.