PEI-cellulose nanocrystal hybrids as efficient siRNA delivery agents—Synthesis, physicochemical characterization and in vitro evaluation

•We report a novel cellulose nanocrystals/PEI based siRNA delivery system.•CNCs/PEI/siRNA formed 290nm – long nanorods.•CNCs/PEI nanoparticles performed a total protection of siRNA against RNase.•Complexation of siRNA to CNCs/PEI helped its cellular uptake.•Viability of CNCs/PEI/siRNA transfected cell was investigated in two cell lines. We describe the synthesis of cellulose nanocrystals (CNCs) complexed to siRNA. PEI (600Da) was first covalently attached to CNCs by reductive amination reaction, then CNCs-PEI were loaded with siRNA, resulting in the formation of CNCs-PEI-siRNA particles, strongly stabilized by ionic interactions. Efficient cellular uptake of these particles was monitored by ethidium bromide staining. Not only did CNCs-PEI show no cytotoxicity at the studied concentrations, but they also protected siRNA from degradation and favored its delivery into the cells. This siRNA (siRNA killer) is able to silence the expression of cell cycle genes and to induce cell death by apoptosis. Therefore, this study suggests that these CNCs-PEI are promising non-viral nanovehicles for siRNA delivery and for efficient anti-tumor strategy.