Mercedes Perez Mendez - pH-induced size changes in solutions of cholesteric liquid-crystal  polymers studied by SANS

Document created by Mercedes Perez Mendez on Apr 8, 2016Last modified by Mercedes Perez Mendez on Apr 8, 2016
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  Publication Details (including relevant citation   information):

  Journal of Physics: Conference Series 554 (2014) 012011,Dynamics   of Molecules and   Materials-II, doi:10.1088/1742-6596/554/1/01201, 




    Polycations possessing substantial buffering capacity below   physiological pH, are intrinsically efficient transfection   agents. These vectors have been shown to deliver genes as well as   oligonucleotides, both in vitro and in vivo, by protecting DNA   from inactivation by blood components. Their efficiency relies on   extensive endosome swelling and rupture that provides an escape   mechanism for the polycation/DNA complexes. Recently,   biocompatible cationic cholesteric liquid-crystal polymers   (ChLCP) have proved able to condense and successfully transfect   DNA, acting as non-viral vectors. Here the radius of gyration of   the new ChLCPs is determined by SANS as a function of pH, the   ultimate aim being to correlate changes in polymer conformation   with membrane activity. With increasing pH the polymers apparent   radii of gyration increased to a maximum, before subsequently   decreasing. This molecular expansion, on passing from acidic pH   environment (cf., lysosome pH 3.5- 4, late endosome pH 5- 6,   early endosome pH 6- 6.5) to neutral pH (cytosol pH=7-7.4),   matches the endocytic route through the cell, where the pH change   is used as a signal to release biomacromolecules, such as DNA. It   confirms that the new cationic ChLCPs could act as an   endosomolytic release system in gene therapy according to the   hypothesis of "the proton sponge".

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