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Analysis of drug coated polymer stents studied by XPS

Cardiovascular interventional therapy with stents has emerged as the most effective method for coronary heart disease. However, thrombosis and hyperplasia are the usual pathological responses to the implantation of foreign devices. To suppress this immune response and that of overgrowth and subsequent restenosis anti-inflammatory drugs are now loaded onto the surface of stent implants. Here we investigate the surface of drug loaded polymer stents. The stents are made of polylactic acid (PLA) dosed with an anti-inflammatory drug with a molecular structure of C51HxNO13. XPS yields quantitative information regarding drug distribution and using Argon cluster sputtering we can see the distribution of the drug into the stent structure. Analysis is also performed on stents submerged in buffer solution (PBS) to see the effects on ageing and the propensity for the drug to migrate into the solution with time.

XPS analysis of frozen 1,4-dibromobenzene

The molecule 1,4-dibromobenzene is of interest as a precursor for the synthesis of conjugated polymers with applications in nanoelectronic and electronic devices. 1,4-dibromobenzene has a vapour pressure of 0.0575 mmHg at 25˚C such that it will volatilise in vacuum at room temperature. To achieve XPS characterisation this organic material requires cooling to < -100˚C before pumping and introduction to the analysis chamber.

Combined Argon cluster UPS-XPS depth profile of OLED thin-film

Low-energy argon cluster ions were used to depth profile through an organoelectronic (TCTA) thin-film deposited on ITO. XPS and UPS spectra were acquired after each etching cycle. Compositional changes were seen through the film and at the interface with the substrate. Changes in UPS spectra were directly compared to changes in compositional change.

Investigating the surface and interface of Li ion thin-film battery materials

Here we use conventional surface analysis techniques of XPS and sputter depth profiling to understand the surface and bulk chemistry of LiPON films formed via atomic-layer deposition (ALD).  Comparisons are made between the results obtained from conventional monatomic depth profiling and cluster depth profiling.

Spherical mirror analyser (SMA)

This technical note outlines the properties and uses of the spherical mirror analyser (SMA) for XPS imaging and it's integration into a modern photoelectron spectrometer.  It details the electron optical properties of the analyser for high energy and spatial resolution imaging.

Getting more from XPS imaging : multivariate analysis

Here we review the properties of the SMA including spatial and energy resolution and provide examples of the capabilities of such an imaging analyser.  In the last few years the combination of the SMA with a two-dimensional, pulse counting electron detector has again increased the level of information available for surface characterisation.  Generating such information requires the acquisition of multi-spectral datasets comprising a series of images incremented in energy so that each pixel contains photoelectron intensity as a function of energy. The datasets generated by this method contain >65,500 spectra and are therefore ideally suited to multivariate analysis to analyse the information content of the dataset and as a tool for noise reduction in individual images or spectra.

Surface chemistry of plasma coated textiles studied by XPS

The performance of fluorinated textile treatment methods, in terms of wash resistance, was evaluated by XPS. Two different fluorination methods, solution based treatment and plasma polymer deposition, and four different textiles were studied with a view to producing long lasting, high performance clothing systems for outdoor activities. An important attribute of such textiles is the ability of the surface of the material to retain or regain its liquid repellent nature following conventional washing cycles.
XPS analysis revealed the degree of surface fluorination before and after wash cycles enabling the durability of the thin film coatings to be evaluated. Results indicated that for most materials the plasma polymer coated textiles exhibited better performance in terms of fluorine coverage and retention than the solution based fluorination metho

Sample cleaning using Ar-GCIS

Typical samples are often presented for analysis following transportation in a less than ideal environment. This results in an analysis and measured surface composition that is not representative of the true surface of the original material. There are a limited number of methodologies available that can effectively clean the sample and restore the original surface without inducing some additional chemical changes and thereby changing the very surface that is being investigated. The development of Ar-gas cluster ion source has changed this.

Smart phone screen – depth analysis of alkali and alkali earth metals

In this study we apply the technique of depth profiling to analyse the concentration of elements in the near surface region of smart-phone display glass. We will look at the distribution of alkali and alkali earth metals - in particular K which is a key element in the glass toughening process. Two different depth profiling methods were used, monatomic Ar and Ar cluster, and a comparison is made regarding the ion bombardment effects of these two methods.  We emphasise the importance of ion choice when depth profiling inorganic materials in particular those containing light alkali metals.