FTIR spectra of CS and CS-<i>g</i>-PEI copolymers with different grafting degrees.

<p>FTIR spectra of CS and CS-<i>g</i>-PEI copolymers with different grafting degrees.</p

Fluorescence images of HEp-2 cells exposed to the polyplexes (N/P = 6) after transfection of 24 h.

<p>(a) CS/pDNA, (b) CS-<i>g</i>-PEI-0.9/pDNA, (c) CS-<i>g</i>-PEI-1.8/pDNA, (d) CS-<i>g</i>-PEI-4.5/pDNA, (e) CS-<i>g</i>-PEI-9.0/pDNA, (f) PEI-1.8/pDNA and (g) PEI-25, using pGFP-N2 as report gene. Relative quantitative GFP expression efficiency of polyplexes was shown (h).</p

Molecular weight (<i>M</i>_w) of CS-<i>g</i>-PEI copolymers measured by GPC.

<p>Molecular weight (<i>M</i>_w) of CS-<i>g</i>-PEI copolymers measured by GPC.</p

Buffering capacity of CS, CS-g-PEI copolymers, PEI-1.8 and PEI-25 measured by acid-base titration.

<p>Buffering capacity of CS, CS-g-PEI copolymers, PEI-1.8 and PEI-25 measured by acid-base titration.</p

Ionic liquid anions hydrogen-bonding with ammonium ions in the activated complex.

<p>(a) activated complex of CS and CDI, (b) activated complex of PEI and CS-CDI intermediate.</p

Buffering capacity in 150 mM NaCl solutions.

<p>NaCl blank (⬟), CS (■), CS-<i>g</i>-PEI-0.9 (+), CS-<i>g</i>-PEI-1.8 (▲), CS-<i>g</i>-PEI-4.5 (▼), CS-<i>g</i>-PEI-9.0 (◆), PEI-1.8 (★) and PEI-25 (●).</p

¹H NMR spectra of CS and CS-<i>g</i>-PEI copolymers with different grafting degrees.

<p>¹H NMR spectra of CS and CS-<i>g</i>-PEI copolymers with different grafting degrees.</p

Grafting PEI-1.8 to CS via CDI to synthesize CS-<i>g</i>-PEI in [BMIM]Ac.

<p>Grafting PEI-1.8 to CS via CDI to synthesize CS-<i>g</i>-PEI in [BMIM]Ac.</p

Particle sizes and ζ-potentials of CS/pDNA and CS-<i>g</i>-PEI/pDNA polyplexes (N/P = 6) determined by DLS.

<p>Particle sizes and ζ-potentials of CS/pDNA and CS-<i>g</i>-PEI/pDNA polyplexes (N/P = 6) determined by DLS.</p

Luciferase expression in HEp-2 cells.

<p>Transfection with CS/pDNA and CS-<i>g</i>-PEI/pDNA polyplexes at various N/P ratios using pGL3 as report gene, PEI-25 as positive control.</p