OICC Press Journal of Nanostructure in Chemistry 2193-8865 13 6 (December 2023) 2022 03 31 Double-grafted chitosans as siRNA nanocarriers: effects of diisopropylethylamine substitution and labile-PEG coating 10.1007/s40097-022-00487-0 EN André Miguel Martinez Junior Department of Chemistry and Environmental Sciences, IBILCE, São Paulo State University-UNESP, R. Cristóvão Colombo, São José do Rio Preto, SP, 2265, 15054-000, BR Ricchard Hallan Felix Viegas de Souza Department of Physics, IBILCE, São Paulo State University-UNESP, São José do Rio Preto, BR Maicon Segalla Petrônio Department of Chemistry and Environmental Sciences, IBILCE, São Paulo State University-UNESP, R. Cristóvão Colombo, São José do Rio Preto, SP, 2265, 15054-000, BR Grazieli Olinda Martins Department of Chemistry and Environmental Sciences, IBILCE, São Paulo State University-UNESP, R. Cristóvão Colombo, São José do Rio Preto, SP, 2265, 15054-000, BR Júlio Cesar Fernandes Orthopedic Research Laboratory, Hôpital du Sacré-Coeur de Montréal, Université de Montréal, Montréal, CA Mohamed Benderdour Orthopedic Research Laboratory, Hôpital du Sacré-Coeur de Montréal, Université de Montréal, Montréal, CA Vera Aparecida Oliveira de Tiera Department of Chemistry and Environmental Sciences, IBILCE, São Paulo State University-UNESP, R. Cristóvão Colombo, São José do Rio Preto, SP, 2265, 15054-000, BR Marcio José Tiera Department of Chemistry and Environmental Sciences, IBILCE, São Paulo State University-UNESP, R. Cristóvão Colombo, São José do Rio Preto, SP, 2265, 15054-000, BR Journal Article 2022 03 31 Abstract The preparation of safe and efficient siRNA carriers remains a challenge that has limited the therapeutic applications of siRNA. In this study, the design of a new small interfering RNA (siRNA) carrier based on diisopropylaminoethyl-chitosan was devised for application in non-viral gene therapy. Polycations having varied proportions (11–32%) of diisopropylethylamine groups (DIPEA) and grafted with polyethylene glycol (1–3%) were synthesized and characterized. The physicochemical and biological properties of the polymers and their nanoparticles were evaluated at pH 6.3 and pH 7.4. The degrees of ionization at pH 7.4 were precisely controlled by the composition and increased from 13% for chitosan to 47% for the more substituted derivative. Nanoparticles with very low toxicities and sizes in the range of 100–200 nm, remained stable up to 24 h after their preparation in both the evaluated pHs under plasma osmolality. As probed by scanning electron and confocal microscopies, an efficient cell uptake of spherical nanoparticles mediated a TNFα knockdown of almost 60% in RAW 264.7 macrophages, and mRNA silence levels higher than the Lipofectamine (up to 90%) in HeLa cells. Overall, the results showed that these derivatives are promising vectors for in vivo studies under physiological conditions. Graphical abstract