Fig. 5. PSNAs loaded with targeting peptide tetanus toxin fragment C deliver a small molecule (Rhodamine 6G) and siRNA to neuronal cells. (a) Delivery of encapsulated Rhodamine 6G. NSC34 cells were incubated overnight with rhodamine-loaded PSNAs (2 × 10¹⁰ per well) with and without targeting peptide TTC (2% mol fraction w.r.t. polymer). Scale bars 200 μm. (b) Knockdown of C9orf72 in NSC34 cells by siRNA tethered to the PSNA corona. PSNAs loaded with siRNA (10% molar ratio to polymer molecules) were used to evaluate the effects of particle dose and of surface density of targeting ligand TTC on gene expression. 2% TTC loading dramatically increases delivery efficiency: the dose at which maximum knock-down is accomplished is reduced by three orders of magnitude. All conditions used 50,000 cells per well, harvested 48 h after treatment. Controls: siRNA and a scramble control (SCR) delivered using cationic lipid transfection agent Lipofectamine™ RNAiMAX at a final concentration of 50 nM. Data presented is mean and SD (n = 3). Samples were compared using a one-way ANOVA with Dunnett's multiple comparison test *p < 0.05, **p < 0.01, ****p < 0.0001.