In the last month I decided to focus my attention on polyelectrolyte layers internal structure and its influence on physico-chemical properties of the multilayer coating. Therefore I made a literature review and I prepared a series of samples for FTIR (Fourier Transform Infrared Spectroscopy) evaluation. Fourier Transform Infrared Spectroscopy is a very sensitive technique to investigate the internal structure of thin films. This is due to the fact that polypeptides, proteins and polysaccharides have specific vibration modes that can be clearly identified by infrared spectroscopy. The amide I and amide II bands of polypeptides and proteins are investigated and their decomposition allows to obtain access to the respective percentages of the different types of secondary structures (α-helix, β-sheet, random structures) [1]. For polysaccharides, the saccharide rings as well as the negatively charged carboxylic and sulfate groups present well defined chemical signatures that can be used to determine the composition of complex mixtures. It is possible to quantify ion pairing in thin films, i.e; to give a quantitative estimate of the amounts of positive and negative charges interacting between each other [2].

1. Roach P., D. Farrar, and C. C. Perry. 2005. Interpretation of protein adsorption: surface-induced conformational changes. J. Am. Chem. Soc. 127:8168-73.
2. Crouzier T., and C. Picart. 2009. Ion pairing and hydration in polyelectrolyte multilayer films containing polysaccharides. Biomacromolecules 10:433-442.

In February I also continued issue concerning polyelectrolyte coatings optimal stiffness determination. Herein I have performed observations of growth and cell morphology of commercially available HUVEC line and fibroblast line on the prepared during the previous month functionalized polyelectrolyte surfaces with varying degrees of chemical cross-linking.