Aqueous solution behaviour and membrane disruptive activity of pH-responsive PEGylated pseudo-peptides and their intracellular distribution. Biomaterials

Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge, CB2 3RA, UK.
Biomaterials (Impact Factor: 8.56). 12/2008; 29(32):4333-40. DOI: 10.1016/j.biomaterials.2008.07.040
Source: PubMed


The effect of PEGylation on the aqueous solution properties and cell membrane disruptive activity of a pH-responsive pseudo-peptide, poly(l-lysine iso-phthalamide), has been investigated by dynamic light scattering, haemolysis and lactate dehydrogenase (LDH) assays. Intracellular trafficking of the polymers has been examined using confocal and fluorescence microscopy. With increasing degree of PEGylation, the modified polymers can form stabilised compact structures with reduced mean hydrodynamic diameters. Poly(l-lysine iso-phthalamide) with a low degree of PEGylation (17.4 wt%) retained pH-dependent solution behaviour and showed enhanced kinetic membrane disruptive activity compared to the parent polymer. It facilitated trafficking of endocytosed materials into the cytoplasm of HeLa cells. At levels of PEGylation in excess of 25.6 wt%, the modified polymers displayed a single particle size distribution unresponsive to pH, as well as a decrease in cell membrane lytic ability. The mechanism involved in membrane destabilisation was also investigated, and the potential applications of these modified polymers in drug delivery were discussed.

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Available from: Rongjun Chen, Dec 08, 2014
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    • "Haemolysis was evaluated by measuring haemoglobin absorbance at 541 nm [21] [24] using a Spectronic UV1 spectrophotometer (Thermo Fisher Scientific, USA). The Drabkin's method for haemoglobin assay [6] [15] was not employed because methaemoglobin concentration was insignificant at all steps of trehalose loading and cryopreservation (data not shown). "
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