Transgene expression mediated by CS-ZN-NIMs following incubation in simulated intestinal fluid (SIF). (A) The effect of intestinal enzyme-mediated degradation of CS-ZN-NIMs on transgene expression. Particles formed with varying zein solutions (5, 7, 10, 12, 15, and 25%) were incubated in either SIF containing pancreatin (+ SIF) or PBS (− SIF) ***, *, and ns indicate p ≤ 0.001, 0.05, and no significance, respectively for +SIF conditions compared to their respective −SIF condition (n = 6). While the overall trend in transgene expression was found to increase with increasing ZN concentration, there were no statistical differences in transgene expression with increasing ZN concentrations, with the exception of the 5 and 25% ZN conditions (p ≤ 0.05). (B) Transgene expression of CS-ZN-NIMs formed with varying zein solutions and varying CS/DNA NPs (n = 3). Asterisks (*) indicate significance between CS:DNA = 5 and CS:DNA = 10 conditions, ***, and ** p ≤ 0.001 and 0.01, respectively. Plus signs (+) indicate significance between CS:DNA = 5 and CS:DNA = 25 conditions, +++, + p ≤ 0.001 and 0.05, respectively. Diamonds (◆) indicate significance between CS:DNA = 10 and CS:DNA = 25 conditions ◆◆, ◆ p ≤ 0.01 and 0.05, respectively. (C) Transgene expression mediated by CS-ZN-NIMs after varying incubation times in SIF containing pancreatin.