Abstract
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".
Highlights
The introduction of exogenous genetic material in cells is a key stage in the development of basic research in cellular biology
We have previously shown that due to their lyotropic behaviour, these cholesteric liquid-crystal polymers (ChLCP) can entrap smaller molecules inside [12] and interact with liquid-crystalline biomacromolecules, such as nucleic acids and lipids
These pH values were chosen to match the values in different cellular compartments
Summary
The introduction of exogenous genetic material in cells is a key stage in the development of basic research in cellular biology. These complexes were successfully tested as non-viral vectors in gene therapy, both in vitro and in vivo [16, 17]. Polyplexes of the cationic ChLCP PTOBEE-NH2 with the commercial anionic polynucleotide [Poly-C-Poly-G] have been studied by contrast variation small-angle neutron scattering (SANS), exploiting the difference in neutron scattering length densities (NSLD) of the two components (1.887E+10/cm for PTOBEE-NH2, 3.320E+10/cm for [Poly-C-Poly-G]) to separately distinguish both component structures, and to highlight the whole polyplex, without any selective deuteration [19] This provided complementary information to that obtained by SAXS [20]. The pH of an endosome is lower than that of the cytosol by up to two pH units, depending on the stage of endosomal development
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
