http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Haniye Najafi,Ali Mohammad Tamaddon,Samira Sadat Abolmaali,Bahareh Owrangi,Younes Ghasemi 한국고분자학회 2015 Macromolecular Research Vol.23 No.7
To improve transfection of plasmid DNA as well as serum protein stability of polyionic complex nanoparticles of branched polyethyleneimine (bPEI), poly(ethylene glycol) (PEG)-stabilized nanoparticles were made from L-histidine substituted bPEI (PEI-Histidine) synthesized by Fmoc chemistry. The polymer was characterized by TNBS assay, 1H NMR, GFC, potentiometric titration and elemental analysis of carbon and nitrogen, DNA condensation, and the stability against extracellular matrix (heparin sulfate) was investigated by dye exclusion and agarose gel retardation assays. The nanoparticles were characterized by dynamic light scattering-zeta potential analyzer. Cytotoxicity and expression of enhanced green fluorescent protein (EGFP) were determined in hepatocellular carcinoma by MTT assay and fluorescent techniques. PEI-Histidine showed a reduced pKa without any significant loss of total primary amines. Plasmid DNA was condensed almost thoroughly with PEGylated polymers, either bPEI or PEI-Histidine, at lower critical N/P ratios. PEGylated PEI-Histidine showed the better resistance to heparin induced displacement and the lower cytotoxicity when it was compared to bPEI. Interestingly unlike bPEI, smaller and less positively charged nanoparticles were obtained from PEGylated PEI-Histidine at N/P ratio=2 that resulted in about 4 folds higher EGFP expression than bPEI without any significant cytotoxicity. These properties are consistent with the higher serum protein resistance and buffer capacity of PEGylated PEI-Histidine at endosomal acidic pH.