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. 2019 Jul 27;214:30–49. doi: 10.1016/j.trsl.2019.07.011

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Fig 6 — Chemical structures of PEI and Chitosan. Polyethylenimine (PEI) has been used in conjugation with other delivery systems to enhance cellular delivery of siRNA. Chitosan, a linear polysaccharide, has been used as a biocompatible and biodegradable alternative to PEI.