Polyelectrolyte complex (PEC) micelles rely on electrostatic interactions between oppositely charged polyelectrolytes, including proteins of sufficient charge density, to drive self-assembly into stable, uniformly sized, nano-scale micelles. Because PEC micelles are able to incorporate charged proteins, they have been used to overcome the challenge of intracellular protein delivery. Here, we expand the utility of PEC micelles by using a pH-responsive PEC micelle to deliver a cas9 ribonucleoprotein complex (RNPs) to mammalian cells via endocytosis. The cas9 RNPs were supercharged and then mixed with a hydrophilic-cationic diblock copolymer to form spherical, nanometer-scale micelles. The block copolymer and methods of supercharging were chosen to maximize responsivity to endosomal conditions to facilitate endosomal escape, with dynamic light scattering indicating pH-induced dissolution of micelles at endosomal pH and long-term stability at neutral pH. Transmission electron microscopy additionally confirms the spherical nature and relatively uniform size of the micelles. Mammalian cells were co-incubated with micelles to evaluate cellular delivery efficiency.

pH-Responsive polyelectrolyte complex micelles for encapsulation and delivery of Cas9 RNPs

ACS Spring Meeting 2021

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