Determination of physicolchemical properties of sterically stabilized immunoliposomal islet neogenesis-associated protein

Objective To study the preparation methods,physical and chemical properties of the islet neogenesis-associated protein (INGAP) sterically stabilized immunoliposomes. Methods An endgroup functionalized polyethylene glycol-lipid deirvative (pyridylthiopropionoylamino-polyethylene glycol-hydrogenated soy phosphatidylethanolamine,PDP-PEG-HSPE) was synthesized and incorporated to sterically stabilized liposomes. After mild thiolysis of the PDP groups by dithiothreitol,liposomes were covalently linked with maleimide-derivatized INGAP and formed sterically stabilized immunoliposomes. The size dis- tribution,immunoreactivity of INGAP-modified sterically stabilized liposomes (INGAP-SIL[HGF]) and specific binding properties of the INGAP-SIL[HGF]to ARIP cells were determined,separately. Results The INGAP-SIL[HGF]had a narrow size distribution after extrusion and the mean size of this immunoliposomes was (95. 86 ± 6. 54)nm,encapsulation efficiency was (88. 37 ± 3. 58)% . The immunoreactivity of INGAP can be preserved after efficient attachment of maleimide-derivatized INGAP to the surface of liposomes. But calculated per antibody concentration,the immunoreactivity of INGAPP-SIL[HGF] would obviously decrease compared to that of INGAP-SIL[HGF]. Significantly higher bindingof INGAP-SIL to fixed ARIP cells directed by INGAP was obtained compared to other preparations. Conclusion INGAP-SIL[HGF]prepared by PDP-PEG-HSPE method maintains stabile physicolchemical properties and most immunoreactivity of INGAP and is able to bind nuclear antigens in vitro.