Cleaning of albumin-contaminated Ti and Cr surfaces: an XPS and QCM study

The cleaning of protein-contaminated metallic surfaces is a major challenge for non-disposable devices used for biomedical applications and in the food industry. The objective of this work is to estimate the cleaning efficiency of sodium dodecyl sulfate (SIDS) buffered at pH 7.4, as a function of temperature, for an immersion time of 15 h. Bovine serum albumin (BSA) is pre-adsorbed on pure Ti- and Cr-deposited quartz crystals. BSA adsorption and removal were investigated by X-ray photoelectron spectroscopy (XPS) and quartz crystal microbalance (QCM). Before cleaning, the amount of adsorbed BSA corresponds to one monolayer, and the oxide thickness is about 5 nm for the Cr quartz [Cr3+ in oxide and hydroxide). For Ti quartz, the metal is not detected (10 nm or more of Ti4+ in TiO2). The C 1s and N 1s peaks indicate that the cleaning with SDS is achieved at 37 degrees C for Ti. For Cr, there are no significant changes from 37 to 60 degrees C. At 80 degrees C, the surface is partially cleaned (70% efficiency); at 90 degrees C, the surface cleaning with SDS is achieved (90% efficiency). The oxide layer of the chromium sample has not changed in composition and thickness. QCM measurements were performed at 37 degrees C. Switches between BSA and SDS solutions indicate that for Ti, SDS induces partial BSA removal (40% efficiency) after similar to 20 min, while for Cr it seems that SDS adsorbs reversibly on the BSA layer, without any cleaning effect. Thus, QCM results are in agreement with XPS data obtained at the same temperature. Copyright (c) 2008 John Wiley & Sons, Ltd.