Construction and evaluation of non-specific targeting cationic polymer lipid liposomes / 药学学报

A new class of dendrimer polylysine poly(ethylene glycol)-lipid was designed and synthesized. The cationic polymer liposomes were prepared by the lipid film-extrusion and post-insertion two methods with these dendrimer polylysine poly(ethylene glycol)-lipid and other lipids. The structural properties of obtained cationic polymer liposomes were studied by laser light scattering and fluorescence spectrometer. It was demonstrated that the nano sized liposomes with different density of surface cationic charges can be prepared by either lipid film-extrusion or post-insertion methods, but post-insertion process did not affect drug loading, did not influence drug loading capacity and did not induce liposomal morphology and particle size. The density of positive charge does not affect the size and distribution of different liposomes size and distribution. It was the better choice for manufacture because post-insertion method did not cause early release of drug and size changes. Cell binding experiments show that cationic polymer liposomes, especially dendrimer polymer liposomes had higher local charge density, and therefore have dramatic non specific cell targeting ability.

Acid-sensitive polymer liposomes prepared by poly(2-ethylacrylic acid) alkylamide derivatives / 药学学报

Poly (2-ethylacrylic acid) (PEAA) alkylamide derivatives were synthesized for constructing pH-sensitive liposomes by partially modification of carboxylic groups of PEAA with chemical reaction. These lipid derivatives of PEAA were synthesized by partially modification of carboxylic groups of PEAA with alkylamines. The acid-sensitive polymer associated liposomes were obtained by the method of polymer self-insertion in aqueous solutions through inserting hydrophobic lipid anchors of the polymer PEAA derivatives into the outer layer of vesicles. Factor effects on polymer insertion into liposomes were evaluated and the pH-sensitivity of the polymer associated liposomes was studied by calcein release assay. The PEAA-assoeiated-liposomes were prepared successfully by the methods of self-insertion. The PEAA-associated-liposomes are shown to be stable at neutral pH. (1) There was no correlate of anchor density of PEAA with length of the alkyl chain, but was positively correlated with the degree of PEAA modification. (2) Polymer insertion increased with initial ratio of polymer to lipid. (3) Unerting hydrophobic lipidr acidic conditions the associated polymer induces membrane disruption and fusion. (4) The PEAA-associated-liposomes shown pH-sensitive drug release property under acidic conditions. The anchored-poly (ethylacrylic acid) lipid derivatives can be useful in developing a potential pH sensitive drug delivery system.