Detection and determination of surface levels of poloxamer and PVA surfactant on biodegradable nanospheres using SSIMS and XPS

The surface chemical characterisation of sub-200 nm poly(DL-lactide co-glyc olide) nanospheres has been carried out using the complementary analytical techniques of static secondary ion mass spectrometry (SSIMS) and X-ray phot oelectron spectroscopy (XPS). The nanospheres, which are of interest for si te-specific drug delivery, were prepared using an emulsification-solvent ev aporation technique with poly(vinyl alcohol), Poloxamer 407 and Poloxamine 908 respectively as stabilisers. The presence of surfactant molecules on th e surface of cleaned biodegradable colloids was confirmed and identified on a qualitative molecular level (SSIMS) and from a quantitative elemental an d functional group analysis (XPS) perspective. SSIMS and XPS data were also used in combination with electron microscopy to monitor the effectiveness of cleaning procedures in removing poorly bound surfactant molecules from t he surface of nanospheres. The findings are discussed with respect to the d evelopment of nanoparticle delivery systems, particularly the composition o f the surface for extending blood circulation times and achieving site-spec ific deposition. (C) 1999 Elsevier Science BN. All rights reserved.