Widely-used approaches to improving polymeric siRNA delivery include conjugation to PEG and targeting ligands (A) and introduction of disulfide bridges for controlled cytoplasmic release (B). Part A reprinted with permission from Christie, R. J.; Matsumoto, Y.; Miyata, K.; Nomoto, T.; Fukushima, S.; Osada, K.; Halnaut, J.; Pittella, F.; Kim, H. J.; Nishiyama, N.; Kataoka, K.: Targeted Polymeric Micelles for siRNA Treatment of Experimental Cancer by Intravenous Injection. ACS Nano
2012, 6, 5174–5189.106 Copyright (2012) American Chemical Society. Part B reprinted from Journal of Controlled Release, 150/2, van der Aa et al, Optimization of poly(amido amine)s as vectors for siRNA delivery, 177–186,112 Copyright (2011), with permission from Elsevier.