Understanding How Cationic Polymers’ Properties Inform Toxic or Immunogenic Responses via Parametric Analysis

Cationic polymers are widely used
materials in diverse biotechnologies.
Subtle variations in these polymers’ properties can change
them from exceptional delivery agents to toxic inflammatory hazards.
Conventional screening strategies optimize for function in a specific
application rather than observing how underlying polymer–cell
interactions emerge from polymers’ properties. An alternative
approach is to map basic underlying responses, such as immunogenicity
or toxicity, as a function of basic physicochemical parameters to
inform the design of materials for a breadth of applications. To demonstrate
the potential of this approach, we synthesized 107 polymers varied
in charge, hydrophobicity, and molecular weight. We then screened
this library for cytotoxic behavior and immunogenic responses to
map how these physicochemical properties inform polymer–cell
interactions. We identify three compositional regions of interest
and use confocal microscopy to uncover the mechanisms behind the observed
responses. Finally, immunogenic activity is confirmed in vivo. Highly cationic polymers disrupted the cellular plasma membrane
to induce a toxic phenotype, while high molecular weight, hydrophobic
polymers were uptaken by active transport to induce NLRP3 inflammasome
activation, an immunogenic phenotype. Tertiary amine- and triethylene
glycol-containing polymers did not invoke immunogenic or toxic responses.
The framework described herein allows for the systematic characterization
of new cationic materials with different physicochemical properties
for applications ranging from drug and gene delivery to antimicrobial
coatings and tissue scaffolds.