Real‐time spectroscopic ellipsometry for protein adsorption study and pH effect

Abstract

Carbon based thin films, such as amorphous carbon (a‐C) and amorphous hydrogenated diamond‐like carbon (a‐C:H) are considered as excellent candidates for biomedical applications. Protein adsorption is an important aspect for the improvement of many applications, such as medical implants, biosensor design, etc. The density, orientation, and conformation of surface‐bound proteins are believed to be key factors in controlling subsequent cellular adhesion. Aim of this work is the study of the pH effect on fibrinogen adsorption on a haemocompatible a‐C:H thin film developed by rf reactive magnetron sputtering. For this purpose, Vis–UV Spectroscopic Ellipsometry (SE) has been used. It is a non destructive, surface sensitive technique, with the capability of performing real‐time measurements in air as well as in liquid environment, with great potential in biomedical studies. An appropriate ellipsometric model has been developed, in order to describe accurately the protein adsorption mechanisms in real‐time. SE results reveal the differences in the rate of fibrinogen thickness increase and transition rate of fibrinogen from liquid to adsorbed state. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Sum Frequency Generation Studies on Bioadhesion: Elucidating the Molecular Structure of Proteins at Interfaces

“…With AFM, different model surfaces have been examined: mica, [77–84] graphite, [77, 78, 82, 84] silicon, [85–87] silicon dioxide, [18, 88] titanium oxide, [89] titanium, [90] stainless steel, [75, 91] carbon thin films, [92] surface-assembled monolayers, [84, 93–95] and different types of polymers. [80, 96–99] Other techniques used over the years have included: scanning probe microscopy, [95, 100] radioisotope labeling, [101–103] X-ray photoelectron spectroscopy, [90] ellipsometry, [92, 104] polarization-modulation infrared reflection-absorption spectroscopy, [75] immunogold staining for imaging, [105] field emission scanning electron microscopy, [106] ELISA,[107] etc. Even mass spectrometry has recently become involved in studying fibrinogen conformations at interfaces.…”