Surface composition of insulin and albumin adsorbed on polymer substrates as revealed by multivariate analysis of ToF‐SIMS data

The structure and the composition of adsorbed protein films containing human serum albumin (HSA) and/or human insulin were studied with time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). The proteins were adsorbed either on native polycarbonate (PC) membranes or on PC membranes treated with poly( N ‐vinylpyrrolidone) (PVP/PC). These membranes have been developed for their use as encapsulation membranes in a bioartificial pancreas. Principal component analysis (PCA) of the ToF‐SIMS results allowed the determination of the main factors affecting the surface structure and composition of the protein layer. The substrate surface properties were found to be the most influencing factor. The amount and type of the adsorbed protein also influence the adsorbed protein layer surface composition and structure. A partial least squares (PLS) regression model allowed confirmation of the correlation between the adsorbed amount of protein and the surface composition of the protein layer.