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. Author manuscript; available in PMC: 2016 Aug 19.
Published in final edited form as: Bioconjug Chem. 2015 Jun 22;26(8):1633–1639. doi: 10.1021/acs.bioconjchem.5b00241

Figure 1.

Figure 1

Synthesis and characterization of s-PEI. A) Reaction of PEI sulfonation. B) Zeta potential of PEI and s-PEI. C) Barium chloride turbidity assay for sulfate detection. D) FTIR spectra of PEI and s-PEI. E) Ninhydrin test for free amines.