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Extracting information on the surface monomer unit distribution of PLGA by ToF‐SIMS
Author(s) -
Ogaki Ryosuke,
Shard Alex G.,
Li Suming,
Vert Michel,
Luk Shen,
Alexander Morgan R.,
Gilmore Ian S.,
Davies Martyn C.
Publication year - 2008
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.2860
Subject(s) - secondary ion mass spectrometry , chemistry , plga , monomer , x ray photoelectron spectroscopy , static secondary ion mass spectrometry , polymer , lactide , mass spectrometry , analytical chemistry (journal) , lactic acid , polymer chemistry , copolymer , chemical engineering , organic chemistry , chromatography , engineering , in vitro , biochemistry , biology , bacteria , genetics
The surface chemistry of a range of random poly l ‐lactide‐co‐glycolide (PLGA) materials has been investigated using XPS, static secondary ion mass spectrometry (SSIMS) and gentle secondary ion mass spectrometry (G‐SIMS). The estimated mole fraction of lactide units provided by SSIMS was in good agreement with bulk composition and appeared not to have been affected by contamination. Conversely, XPS assessment of lactide compositions was unreliable due to hydrocarbon contamination contributions. In this study, we propose a novel model to demonstrate that by using SSIMS it is possible to infer the degree of trans‐esterification for PLGA co‐polymers synthesised from a mixture of lactide and glycolide homo‐dimers. This was determined by introducing two independent parameters, the ratio of trans‐esterified bonds to the total number of ester bonds, P T , and the lactide composition. The model has indicated that, for this set of polymers, P T was approximately 0.25. Furthermore, we have demonstrated that G‐SIMS successfully identified the structurally important key fragments leading to direct identification. Analysis by G‐SIMS showed that the glycolic acid units from all PLGA compositions are emitted in a lower energy‐fragmentation process than lactic acid units. Copyright © 2008 John Wiley & Sons, Ltd.