Characterization of the outmost surface of ion-selective solvent polymeric PVC membranes and protein adsorption

Highly plasticized PVC is the most commonly used membrane matrix of ion-selective sensors. Chemical, physical, and morphological features of plasticized PVC surfaces have been investigated by AFM, TOF-SSIMS acid contact angle measurement. The results show chemical, physical and topographical differences depending on the sample preparation procedure as well as the type and amount of plasticizer used. The surfaces of thin films and thick membranes are markedly different, despite the same nominal bulk composition. Bovine serum albumin (BSA) adsorption on a typical Calf-selective membrane surface is evident from electrical impedance observations, while AFM finds no BSA clusters on the membrane surface.