Size-dependent properties of M-PEIs nanogels for gene delivery in cancer cells.

Polyethyleneimine nanogels (named as M-PEIs) with different sizes were prepared by photo-Fenton reaction in aqueous solution from which samples of 38, 75, 87, 121, 132 and 167nm were selected for in vitro transfection. The homogeneous structure and the same component made it possible to study the size effect of M-PEIs nanogels on gene transfection efficiency when loading the same quantity of plasmid DNA (pLEGFP-C1) into A549, Bel7402, BGC-823 and Hela cells. M-PEIs and its DNA complexes were characterized by photo correlation spectroscopy and atomic force microscopy. The protein expression was observed by flow cytometry and fluorescence microscopy. All of the DNA complexes had no obvious cytotoxicity and the surface charges were positive charged at the optimum weight ratio. Therefore, the expressed protein was affected by the size of M-PEIs when the same quantity of DNA was used to transfect cells. In addition, the samples of 75 and 87nm yielded the highest transfection efficiency about 30% in all of the four cell lines which were also cell line independent.

Properties of radicals formed by the irradiation of wool fibers.

Wool fibers of different sample conditions were irradiated in different atmospheres by (60)Co gamma-rays and were studied by electron spin resonance method (ESR). It was found that a large percentage of the alpha-carbon radicals of polymer main chain were more long-lived radicals. The ESR measurements of irradiated cortex samples of the wool fibers proved that most radicals from the cortex were long-lived ones. Low water content (as low as 27.5%) in the reaction system did not greatly affect the radical formation, but higher water contents would reduce the radical concentrations dramatically and accelerate their decaying process. The results will be of help in property modification of wool products by radiation graft copolymerization.