Characterization of CS/DNA NPs formed via ionic gelation. CS/DNA NPs formed at varying CS:TPP weight ratios were characterized for size (circles) and charge (triangles) (A–C), DNA encapsulation efficiency (D–F), and transfection (G–I). The concentration of the CS solution used in particle formation was held constant at 0.5 mg/mL (A,D and G), 1.0 mg/mL (B, E and H), and 2.0 mg/mL (C, F, and I) for all CS:TPP ratios. All data represented as mean ± SEM (n = 6). Asterisks (*) denote significance compared to 0.5 mg/mL conditions (* p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001). Plus signs (+) denote significance compared to 1.0 mg/mL conditions (++ p ≤ 0.01 and +++ p ≤ 0.001).