Abstract
Axisymmetric drop shape analysis by profile (ADSA-P) was employed to determine the interfacial free energy changes occurring during bovine serum albumin (BSA) adsorption from solution droplets on fluoroethylenepropylene-Teflon (FEP-Teflon). 100 μl droplets of BSA solutions on FEP-Teflon were followed by ADSA-P as a function of time, for up to 60 min, yielding the contact angle and the surface tension, γ lv. By combining these data with Young's equation, while assuming the surface free energy, γ lv of FEP-Teflon to be 20 mj m −2, the interfacial free energy γ sl could be calculated. Both γ lv and γ sl were found to decrease as a function of time, since after positioning of a droplet, BSA adsorption occurs both at the liqui—vapor as well as the solid—liquid interface. Furthermore, linear relations were obtained when plotting γ lv ( t) · cosθ( t), vs γ lv, ( t) with BSA concentration dependent slopes. By employing the Lucassen-Reynders equation and radio-activity data obtained for BSA adsorption on FEP-Teflon, it was possible to estimate BSA adsorption at the liquid—vapor interface.
Published Version
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