Pharmaceutical applications of micro-thermal analysis.

Micro-thermal analysis is a recently introduced thermoanalytical technique that combines the principles of scanning probe microscopy with thermal analysis via replacement of the probe tip with a thermistor. This allows samples to be spatially scanned in terms of both topography and thermal conductivity, whereby placing the probe on a specific region of a sample and heating, it is possible to perform localized thermal analysis experiments on those regions. In this minireview, the principles of the technique are outlined and the current uses within the polymer sciences described. Current pharmaceutical applications are then discussed; these include the identification of components in compressed tablets, the characterization of drug-loaded polylactic acid microspheres, the analysis of tablet coats, and the identification of amorphous and crystalline regions in semicrystalline samples. The current strengths and weaknesses of the technique are outlined, along with a discussion of the future directions in which the approach may be taken.

A comparison of the use of an ATP-based bioluminescent assay and image analysis for the assessment of bacterial adhesion to standard HEMA and biomimetic soft contact lenses.

The aim of this study was to investigate in vitro adhesion of clinically relevant bacteria to standard HEMA and novel biomimetic soft contact lenses (SCL) using bioluminescent ATP assay and image analysis. Unworn SCL were incubated with Pseudomonas aeruginosa, Staphylococcus epidermidis or Serratia marcescens suspended in sterile phosphate buffered saline (PBS). The level of bacterial adhesion after 1, 2, 4, 6 and 18h, was assessed using both image analysis and a bioluminescent ATP assay. Species differences in the overall level of adhesion to the different types of lens were observed using both measurement techniques. Generally bacterial adhesion was shown to peak at 4-6 h, then decline to a much lower level by 18 h. After 4 h, adhesion of all species of bacteria to the biomimetic SCL (omafilcon A) was found to be significantly lower than to the standard HEMA SCL (polymacon) (p<0.05. Student's t-test, n = 4). Both these techniques demonstrated that novel biomimetic SCL materials exhibit significantly lower bacterial adhesion in vitro compared to standard HEMA SCL materials. SCL manufactured with these novel biomimetic materials may reduce the risk of infection.

Structural studies of microcosm dental plaques grown under different nutritional conditions.

The aim of this study was to investigate the structure of intact oral biofilms using confocal laser scanning microscopy (CLSM). Mixed-species biofilms were grown on enamel discs in a constant depth film fermentor. The biofilms were fed with a mucin-containing artificial saliva with or without sucrose supplementation. Biofilms were examined using a Wild-Leitz CLSM, operating in reflected light mode. The microstructure of non-supplemented biofilms was revealed to be complex, with stacks of bacteria developing over time, separated by clear channels. Sucrose-supplemented biofilms appeared to colonise the substratum more rapidly. The results of this study have shown that using CLSM it is possible to examine the structure of oral biofilms grown under conditions similar to those which would exist in vivo.