Elevated atherogenic index following oral administration of quaternized polyamine nanogels

•Quaternized polyamine nanogel possessing PEG shell layer on its surface was synthesized.•Orally administration of Q-nanogel decreased low density lipoprotein (LDL) level.•It is interesting to note that Q-nanogel increased high density lipoprotein (HDL) level, which increased atherogenic significantly.•Q-nanogel did not absorbed blood circulation, thus it will not cause adverse effect to entire body.•Q-nanogel prepared in this study is thus promising as new materials for oral nanotherapeutics for hyperlipidaemia.

Quaternized polyamine nanogels possessing poly(ethylene glycol) (PEG)-tethered chains as the surface layer were prepared by redox-initiated emulsion polymerization of 2-(N,N-diethylamino)ethyl methacrylate (EAMA) in the presence of vinylbenzyl-ended poly(ethylene glycol) (PEG-CH2PhCHCH2), followed by quaternization with methyl iodide (QNG-I). QNG-I absorbed taurocholic acid regardless of environmental pH, because of the fixed positive charge of QNG-I. Oral administration of polyamine nanogels into mice tended to cause intestinal retention, with accumulation of up to 70% of the initial dose. Levels of low-density lipoprotein cholesterol (LDL-C) in hyperlipidemic mice effectively decreased following oral administration of QNG-I. Interestingly, oral administration of QNG-I increased the levels of high-density lipoprotein cholesterol (HDL-C), resulting in an extremely high atherogenic index. Iodide counter-anions in QNG-I played an important role in the increase in HDL-C levels.

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