Quantitation of Complexed versus Free Polymers in Interpolyelectrolyte Polyplex Formulations

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• 作者：Xiaoling Wang ; Sneha S. Kelkar ; Amanda G. Hudson ; Robert B. Moore ; Theresa M. Reineke ; Louis A. Madsen
• 刊名：ACS Macro Letters
• 出版年：2013
• 出版时间：November 19, 2013
• 年：2013
• 卷：2
• 期：11
• 页码：1038-1041
• 全文大小：235K
• 年卷期：v.2,no.11(November 19, 2013)
• ISSN：2161-1653

文摘

The quantity of free polymer in a polymer/DNA complex (polyplex) formulation critically impacts its gene transfection efficiency, cellular uptake, and toxicity. In this study, the compositions of three interpolyelectrolyte polyplex formulations were quantified by a facile NMR method. Using careful integration of a 1D ¹H NMR spectrum with a broad spectral width, the quantities of unbound polymer and polyplexes in solution were determined. Linear polyethyleneimine (PEI) mixed with DNA at polymer amine to DNA phosphate molar ratio (N/P ratio) of 5 revealed an effective binding N/P ratio of 3.5 without excess free polymer. This result is in strong agreement with the stoichiometric number of PEI/DNA binding obtained by isothermal titration calorimetry. The noninvasive nature of this method allows broad application to a range of polyelectrolyte coacervates, opening new opportunities for understanding and optimizing polyelectrolyte complex formation and providing quantitation of complex formation in a single measurement.