Congratulations to Ali Rafati who won second prize in the poster presentations at the recent NMAET III & SSBII 10 meeting at NPL, Teddington, UK with his poster titled 'Quantitative XPS depth profiling of codeine loaded poly(l-lactic) acid films using a coronene sputter source'

Ali's poster with co-authors Alex Shard, Morgan Alexander and Martyn Davies detailed recent data acquired using the polyatomic ion source here in the Manchester applications lab. The work highlights the significant advantages of cluster ion sources for sputter depth profiling of polymeric materials as detailed in the abstract.

Abstract:

For drug eluting stents (DES) the controlled release of active substances over prolonged periods of time is vital for their function. Methods for characterisation of drug and polymer distribution allow inferences to be made regarding the expected release profile in vivo. In this study XPS depth profiling using a novel coronene etching source is employed to ascertain quantitative atomic concentration data through thickness. Flat film models of DES devices containing codeine and poly(l-lactic acid) (PLA) spun cast from chloroform onto Piranha cleaned silicon wafers were produced. Ellipsometry of the films was undertaken before analysis to determine thickness of ~100 nm and provide an estimate of the loading of drug within the PLA matrix through spectroscopic analysis. XPS depth profiling across the range of samples indicated depletion of codeine from the surface and segregation to the bulk of the sample based on uniform distribution of the bulk loading. Surface depletion has important implications for polymer- drug delivery systems as would provide a time lag in the release kinetics [1, 2]. These results lay the foundations for monitoring the distribution in simulated service conditions enabling elution profile interpretation in terms of through thickness drug distribution using XPS depth profiling.

For those registered for the Kratos Users' Area a pdf of the poster is available from the 'Downloads > General Reference' section.